age - related 
 macular degeneration ( amd ) is the leading cause of 
 blindness for individuals aged 60 years or older . an estimated 11 million people in the united states suffer 
 with amd , and this number is expected to increase to 22 million individuals 
 by 2050 because of the projected demographic expansion of the aging 
 population .
current global direct health care costs associated with 
 amd are estimated at $ 255 billion .
there 
 are two forms of amd , dry ( atrophic ) and wet ( neovascular ) , with the 
 more prevalent dry form accounting for nearly 90% of all diagnosed 
 cases .
intravitreal anti - vegf therapies 
 have emerged as a standard of care to treat wet amd ; however , there 
 is currently no fda - approved treatment available for the dry form .
thus , safe and effective treatment of dry amd 
 remains a critical unmet need .
atrophic ( dry ) form of amd represents 
 a slowly progressing neurodegenerative 
 disorder of the eye in which specialized retinal neurons ( rod and 
 cone photoreceptors ) degenerate in the central part of the retina 
 called macula .
histopathological and clinical 
 data suggest that photoreceptor degeneration in dry amd is triggered 
 by abnormalities in the retinal pigment epithelium ( rpe ) that lies 
 beneath photoreceptors and provides critical metabolic support to 
 these light - sensing neuronal cells .
age - dependent 
 accumulation of lipofuscin in the rpe is frequently cited as one of 
 the causes that may potentially contribute to the demise of the rpe 
 in the dry amd retina .
moreover , 
 excessive accumulation of lipofuscin in the retina seems to be the 
 sole causative factor in autosomal recessive stargardt disease , an 
 untreatable form of inherited macular dystrophy caused by genetic 
 mutations in the abca4 gene .
rpe lipofuscin is different 
 from that of other aging tissues , as it contains various bisretinoid 
 fluorophores such as pyridinium bisretinoid n - retinide - n - retinylidene ethanolamine 
 ( a2e ) .
a2e , which is derived from a nonenzymatic 
 condensation between phosphatidylethanolamine and two molecules 
 of all - trans retinal , elicits a myriad of cytotoxic 
 effects such as induction of apoptosis in cultured rpe cells , inhibition of the critical lysosomal transporter , loss of membrane integrity , inhibition of phagocytosis , disruption of mitochondrial 
 function , activation of the complement 
 cascade , and oxidative damage .
given that lipofuscin bisretinoids represent 
 the major cytotoxic component of rpe lipofuscin , it was hypothesized 
 that pharmacological inhibition of bisretinoid formation in the retina 
 may provide a means by which to delay the progression of geographic 
 atrophy in dry amd and suppress degenerative processes in stargardt 
 disease .
indeed , there are several classes 
 of pharmacological treatments inhibiting lipofuscin bisretinoid formation 
 in the retina under investigation for the potential treatment of dry 
 amd and stargardt s disease .
our work focuses 
 on reducing ocular uptake of serum all - trans retinol 
 ( retinol , vitamin a ) ( 1 , figure 1 ) via inhibition of retinol binding protein 4 ( rbp4 ) as a means by 
 which to reduce the concentration of bisretinoid precursors in the 
 retina and inhibit bisretinoid formation .
retinol is an essential 
 nutrient that plays a critical role in a wide variety of biological 
 functions , including fueling the visual cycle .
it is transported to vitamin a dependent tissues as a tertiary 
 complex with rbp4 and transthyretin ( ttr ) .
rbp4 is a lipocalin serum protein primarily 
 secreted from the liver and to a lesser 
 extent from kidney and adipose tissue .
because of the relatively low molecular weight of rbp4 ( 21 kda ) , 
 the rbp4-ttr interaction is critical for maintaining serum retinol 
 in circulation as , without complexation with ttr , rbp4-retinol is 
 rapidly cleared from the bloodstream through glomerular filtration .
rbp4-ttr complexation is retinol dependent , 
 as apo - rbp4 interacts poorly with ttr .
the visual cycle depends on a constant 
 delivery of retinol to the 
 rpe by rbp4 .
it was suggested that rbp4 ligands antagonizing the retinol - dependent 
 rbp4-ttr interaction in circulation would lead to a dramatic reduction 
 in serum levels of rbp4 via renal elimination of the monomeric protein . 
 as a consequence of this renal rbp4 elimination , serum retinol levels 
 and delivery to the rpe
would also be reduced , as would the rate of 
 bisretinoid formation in the retina .
this hypothesis has been preclinically and clinically confirmed 
 with fenretinide ( 2 ) , a synthetic retinoid - based rbp4 
 antagonist .
fenretinide is known to prevent the binding of all - trans retinol to rbp4 and disrupt the retinol - dependent 
 rbp4-ttr interaction in vitro , as well 
 as lower circulating plasma rbp4 levels in vivo .
in addition , fenretinide also significantly reduced accumulation 
 of lipofuscin bisretinoids in the abca4 mouse model of enhanced retinal lipofuscinogenesis . supporting the therapeutic role of rbp4 in 
 dry amd , in extended clinical studies , fenretinide was recently confirmed 
 to reduce serum rbp4 in amd patients .
post hoc analysis of the fenretinide clinical trial data suggests 
 efficacy in reducing the rate of the geographic atrophy growth that 
 was achieved in a subgroup of patients wherein an approximately 70% 
 ( or greater ) reduction in serum rbp4 levels was realized .
prior to their application to the treatment 
 of dry amd and stargardt 
 disease , rbp4 antagonists were previously being considered for the 
 treatment of diabetes .
a1120 ( 3 ) , a lead molecule for this indication , was 
 previously reported by a group at amgen as was its protein - bound crystal 
 structure .
this relatively low molecular 
 weight compound features several key structural elements ; an o - trifluoromethyl arylpiperidine linked via a carbonyl to 
 an unsubstituted anthranilic acid residue . in a study
reported elsewhere , we have shown that chronic a1120 administration 
 reduced accumulation of lipofuscin bisretinoids by approximately 50% 
 in the abca4 mouse model . 

this activity correlated with a 75% reduction in serum rbp4 and 3050% 
 reduction in certain visual cycle retinoids .
however , despite these encouraging preclinical data , a1120 suffers 
 from poor human liver microsomal ( hlm ) stability ( 3% remaining 
 after 30 min incubation ) , thus posing a significant challenge for 
 further development .
therefore , our aim was to design a novel and 
 potent nonretinoid rbp4 antagonist capable of lowering serum rbp4 
 levels in vivo with comparable or superior efficacy and improved druglike 
 characteristics that include an improved hlm metabolic profile .
retinol ( 1 ) , fenretinide ( 2 ) , and a1120 
 ( 3 ) .
the specific protein 
 movements and molecular interactions that 
 mediate agonist driven rbp4-ttr interaction versus holoenzyme and/or 
 antagonist - bound rbp4-ttr disassociation are of great interest in 
 the design of highly potent and selective rbp4 antagonists .
it is 
 for this reason that in our program we measured compound binding affinity 
 to the non - ttr associated rbp4 protein ( spa ) as well as determined 
 the rbp4-ttr antagonist potency ( htrf ) . from evaluation of the reported 
 a1120-bound protein crystal structure
, we speculated that variation 
 in both the linkage and relative orientation of the o - trifluoromethylphenyl and arylcarboxylic acid fragments might further 
 enhance rbp4 antagonist potency as well as permit tuning of the desirable 
 adme characteristics so as to potentially improve hlm stability ( figure 2 ) . using computer - assisted drug design based around 
 several rbp4 protein crystal structures ,
we designed , computationally 
 evaluated , and synthesized illustrative examples of conformationally 
 constrained carboxylic acid based non - retinoid antagonists .
in addition , 
 within the context of the original a1120 structural scaffold , we further 
 explored the rbp4 antagonist activity of several acylsulfonamide carboxylic 
 acid isosteres and arylcarboxylic acid replacements .
lastly , acknowledging 
 earlier patent disclosures of conformationally flexible rbp4 antagonists , we also included in our test set several aliphatic 
 analogues bearing an ether - linked ortho - substituted aryl headgroup 
 and terminal urea - linked carboxylic acid .
medicinal chemistry work 
 plan for the identification of novel , 
 nonretinoid rbp4 antagonists .
by employment of the route reported by swanson 
 and co - workers ( scheme 1 ) , the synthesis of 
 a1120 ( 3 ) and piperidine core intermediate 7 began with lithium 
halogen exchange of 1-bromo-2-(trifluoromethyl)benzene 
 ( 4 ) followed by 1,2-carbonyl addition of the lithium 
 salt to 1-benzylpiperidin-4-one to give tertiary alcohol 5 .
thionyl chloride induced dehydration of 5 to the intermediary 
 tetrahydropyridine 6 followed by reduction of the olefin 
 with concomitant n - benzyl deprotection using ammonium 
 formate and 10% pd / c to afford 7 upon conversion to the 
 hydrochloride salt .
treatment of 7 with methyl 2-isocyanatobenzoate 
 followed by saponification of the methyl ester provided a1120 ( 3 ) in good yield .
our initial strategy to generate acylsulfonamide 
 acid isosteres of 3 involved hatu - mediated activation 
 of the carboxylic acid to be followed by acylation with various desired 
 sulfonamides .
however , we discovered that treatment of 3 with hatu in the absence of nucleophile yielded acyl -lactam 8 , which was isolated via column chromatography .
acyl -lactam 8 ultimately provided a convenient intermediate for the assembly 
 of our desired acylsulfonamides 911 , as it readily underwent ring - opening to the desired analogues upon 
 treatment with preformed sulfonamide sodium salts .
highlighted in scheme 2 are the synthetic 
 routes used to access analogues bearing aliphatic carboxylic acid 
 residues .
piperidine hydrochloride 7 provided a key intermediate 
 for the synthesis of several analogues designed to replace the acylanthranilic 
 acid of 3 with diverse moieties potentially capable of 
 engaging in similar rbp4 binding interactions .
oxoacids 1214 were readily manufactured via acylation of 7 with the corresponding carboxylic acid ester , acid chloride , 
 or anhydride followed by saponification of the pendent ester ( if required ) 
 to give the desired compound . a racemic mixture of proline - based analogue 
 ( )-15 was generated by reaction of methyl 1-(chlorocarbonyl)pyrrolidine-2-carboxylate 
 with 7 followed by hydrolysis of the ester to the desired 
 acid .
the synthesis of acyclic phenoxyethylamido ether 
 analogues 20 , 21 , 25 , and 27 is 
 depicted in scheme 3 .
sn2 displacement 
 of bromide 17 with an appropriately substituted phenol 
 followed by tbs deprotection gave hydroxyl aryl ethers 18 .
treatment of intermediate 19 with methyl 2-isocyanatobenzoate 
 followed by saponification of the methyl ester gave the desired carboxylic 
 acid analogues 20 and 21 .
the syntheses 
 of analogues 25 and 27 began with boc protection 
 of 2-chloroethanamine 22 to give carbamate 23 , which was converted to aryl ether 24 via sn2 displacement with 2-(tert - butyl)phenol .
intermediate 24 was converted to analogue 25 via treatment 
 with methyl 2-isocyanatobenzoate followed by hydrolysis of the methyl 
 ester to the desired carboxylic acid .
intermediary carbamate 23 was also used in a similar fashion to generate the 4-fluorophenyl 
 substituted analogue 27 .
similar to the synthesis 
 of a1120 , the manufacture of these compounds involved treatment of 
 a core secondary amine with methyl 2-isocyanatobenzoate followed by 
 saponification of the resulting ester to give the desired acids .
the 
 synthesis of 3.1.0 bicyclic systems 29 and 30 followed a procedure reported by mchardy and co - workers .
lastly , the aryloxy azetidine core used in the synthesis 
 of analogue 33 followed a synthetic route outlined by 
 pettersson and co - workers . the synthesis 
 of azepine 28 , azetidine 32 , and a racemic 
 mixture of spiroindane ( )-34 began with the commercially 
 available secondary amine cores .
construction of the bicyclic { 3.3.0}-octahydrocyclopenta[c]pyrrolo analogues 43 , ( )-45 , and 48 was achieved following routes previously reported 
 by dart , lauffer , and guillemont ( scheme 5 ) . the synthesis began with a lialh4 reduction 
 of commercially available dione 35 followed by n - boc protection of the resulting secondary amine to give 
 isoindole 36 in good yield .
naio4 and ruo2h2o facilitated oxidative cleavage of 36 gave ring - opened diacid 37 in good yield . 

subsequent dieckman condensation with concomitant decarboxylation 
 of 37 in acetic anhydride at 120 c yielded ketone 38 in 55% yield .
deprotonation of 38 with lihmds 
 followed by treatment with 1,1,1-trifluoro - n - phenyl - n-((trifluoromethyl)sulfonyl)methanesulfonamide 
 provided desired triflate 39 , which underwent smooth 
 conversion to alkene ( )-40 in the presence of ( 2-(trifluoromethyl)phenyl)boronic 
 acid under standard suzuki pd - catalyzed cross - coupling conditions . 

reduction of alkene ( )-40 via 50 psi of h2 in the presence of 10% pd / c in ch3oh provided exclusively endo - product 41 .
boc deprotection of 41 followed by reaction with methyl 2-isocyanatobenzoate and 
 subsequent saponification of the methyl ester afforded desired carboxylic 
 acid analogue 43 .
the core geometry of endo - isomer 43 was confirmed via a h nmr noesy 
 experiment , which exhibited a positive noe enhancement between the 
 benzylic and bridging methine hydrogens .
generation of exo - product 48 could only be achieved via reduction of 
 des - boc olefin ( )-44 , which provided a mixture 
 of endo- and exo - isomers 46 ( free - base of 42 ) and 47 , with endo-46 being the major isomer by hplc ( 10:1 endo / exo ) .
this result was consistent with the observation reported by dart and 
 co - workers and could be attributed to 
 reduction readily occurring at the more accessible convex face of 
 the olefin ( )-44 . the greater degree of selectivity 
 observed for the reduction of n - boc protected intermediate 
 ( )-40 to yield exclusively endo - isomer 41 could be due to further hindrance of hydrogen 
 delivery to the convex face of the olefin by the bulky boc group . 

the core geometry of exo - isomer 48 was 
 also confirmed via a h nmr noesy experiment , which did 
 not exhibit an noe enhancement between the benzylic and bridging methine 
 hydrogens .
related analogues of 43 were accessed via carbamoyl 
 chloride intermediate 49 , which was generated via treatment 
 of amine hydrochloride salt 42 with triphosgene in the 
 presence of pyridine ( scheme 6 ) .
intermediate 49 was reacted with various methyl 2-amino-5-substituted benzoates , 
 which were subsequently hydrolyzed to the desired carboxylic acid 
 analogues 5053 .
carbamoyl chloride 49 could also be treated 
 with heteroanthranilic 
 esters to provide the pyridyl and pyridazinyl bicyclic { 3.3.0}-octahydrocyclopenta[c]pyrrolo analogues 5457 depicted in scheme 7 .
pyridine analogue 54 required an alternative route , which involved a pd - catalyzed 
 amidation of the primary urea of 49 with 2-chloronicotinate .
the amino acid derived analogues shown 
 in scheme 8 were also furnished from key carbamoyl 
 chloride intermediate 49 via treatment with the specified 
 amino acid methyl esters 
 followed by hydrolysis to give the desired carboxylic acids .
drawing from the breadth of reported rbp4 x - ray crystallographic 
 data available , we sought to gain better insight into key rbp4 binding 
 interactions and conformational changes for both agonist and antagonist 
 binding states , which would serve to evaluate our nonretinoid antagonist 
 design proposals . with this goal in mind
, we analyzed binding differences 
 observed in the reported protein data bank ( pdb ) high - resolution x - ray 
 crystal structures 1rbp ( rbp4 cocrystallized with retinol),3bsz ( the 
 rbp4-ttr complex cocrystallized with retinol),1fel ( rbp4 cocrystallized with fenretinide ) , and 3fmz ( rbp4 
 cocrystallized with a1120 ) .
retinol 
 binds within an internal cavity of rbp4 whereby the polyene chain 
 is encapsulated within a -barrel core , the -ionone ring 
 projects into a deep interior hydrophobic pocket , and the terminal 
 hydroxyl group protrudes out of the entrance of the binding cavity 
 toward solvent ( figure 3a ) .
the rbp4 loops 34 ( residues 6368 ) 
 and 56 ( residues 9299 ) surround the 
 opening of the binding cavity and present an interaction surface for 
 ttr engagement .
retinol binding to rbp4 induces 
 conformational changes within these loops that facilitate complexation 
 with ttr .
the rbp4-ttr complex is further stabilized via an h - bond 
 interaction between the hydroxyl group of retinol and gly83 of ttr 
 subunit b. fenretinide also binds within 
 the rbp4 cavity in a similar fashion to retinol ; however , it induces 
 a conformational change within rbp4 loop 34 
 that is unfavorable for rbp4-ttr engagement ( figure 3a ) .
in addition , the fenretinide 
 4-hydroxyphenylamide is also believed to further disrupt rbp4-ttr 
 complexation by projecting into the rbp4-ttr interaction interface 
 where it presents steric clashes with ttr subunits .
a1120 induces significant conformational changes in both rbp4 
 loops 
 34 and 56 that are not 
 conducive for complexation with ttr ( figure 3b ) .
the nonretinoid antagonist binds 
 within the -barrel cavity with the o - trifluoromethylphenyl 
 ring projecting into the hydrophobic -ionone pocket and the 
 anthranilic carboxylic acid fragment positioned at the opening where 
 it engages in several key binding interactions ; the a1120 carboxamidocarbonyl 
 oxygen atom accepts an h - bond from the backbone of leu37 , and the 
 carboxylic acid forms a salt bridge with arg121 and two h - bonds with 
 tyr90 and gln98 ( figure 4a ) .
in addition , a  edge - to - face interaction 
 is observed between the anthranilic carboxylic acid phenyl ring of 
 a1120 and the phenyl ring of phe96 .
of these key binding interactions , 
 it appears that the a1120-gln98 h - bond and the phe96  
 edge - to - face interaction are potentially playing critical roles in 
 inducing and stabilizing the conformational changes observed within 
 loop 56 ( figures 4b ) .
relative 
 rbp4 loop 34 and 56 
 conformational changes for agonist and antagonist binding .
( a ) comparison 
 of the loop 34 and 56 
 conformations for retinol and fenretinide binding to rbp4 : overlay 
 of protein crystal structures 1rbp ( white ) , 3bsz ( green ) , and 1fel ( cyan ) .
fenretinide is shown as magenta , 
 and retinol is shown as yellow ( from 1rbp ) and orange ( from 3bsz ) .
( b ) comparison 
 of the loop 34 and 56 
 conformations for retinol and a1120 binding to rbp4 : overlay of protein 
 crystal structures 3bsz ( green ) and 3fmz ( red ) .
retinol is shown as orange , and a1120 is shown as magenta . with these crystallographic data 
 in hand ,
our medicinal chemistry 
 goals were to design novel , nonretinoid antagonists that would engage 
 in the key aforementioned binding interactions and induce conformational 
 changes in both loops 34 and 56 , 
 thereby leading to disruption of rbp4-ttr complexation .
proposed ligands 
 were initially docked within 3fmz using standard precision ( sp ) mode , and the docking 
 poses were subsequently refined using the extra precision ( xp ) mode 
 of glide ( version 5.8 , schrdinger , llc . ) .
we aligned the glide 
 xp refined docking poses of all proposals to the cocrystallized conformation 
 of a1120 and performed molecular mechanics ( mm ) minimization on these 
 ligands in 3fmz using impact ( version 5.8 , schrdinger , llc . ) . these minimized 
 poses and corresponding glide scores generated
were reported as the 
 final docking poses and glide scores ( glide scores and solvation energies 
 for each analogue are provided in the supporting 
 information ) .
although glide scores provided some guidance 
 for the triaging of compounds yet to be synthesized , these crude estimates 
 were generally limited with regard to consistently predicting relative 
 levels of rbp4 binding affinity .
we found that these scores were useful 
 in prospectively estimating whether a compound would show affinity 
 at rbp4 with potency ( ic50 ) less than 1 m in the 
 spa assay .
however , detailed sar analysis showed that , as expected , 
 the scores exhibited a poor correlation with the actual rbp4 spa assay 
 ic50 results observed .
in addition , glide would occasionally 
 provide inconsistent binding modes for some closely structurally related 
 analogues of a1120 ( e.g. , altered h - bond interactions with either 
 leu37 or tyr90 ) .
therefore , focus shifted away from glide scores and 
 more to the geometric docking of proposed ligands when using the model 
 to triage novel analogue designs prior to synthesis . in this work , 
 our retrospective computational analysis of the rbp4 spa assay sar 
 observed for our novel analogues placed emphasis on correlations between 
 the orientation and positioning of our ligands within the rbp4 binding 
 cavity relative to a1120 ( geometric docking poses generated ) rather 
 than on numeric agreement with the obtained glide scores .
( a ) overlay 
 of protein crystal structures 3bsz ( orange ) and 3fmz ( white ) .
a1120 binding 
 interactions with arg121 , tyr90 , leu37 , and phe96 are highlighted . 

( b ) comparison of rbp4 
 loop 56 conformational changes between fenretinide 
 ( 1fel , yellow , 
 white , and blue ) and a1120 ( 3fmz , red ) binding .
analogue binding 
 affinities for rbp4 were measured using our previously described scintillation 
 proximity assay ( spa ) .
nonlinear regression 
 analysis conducted following saturation binding of retinol to rbp4 
 revealed a kd of 62.5 nm in our assay 
 conditions which is in line with the previously reported 70190 
 nm range of values .
for compound characterization 
 we measured the competitive displacement of radiolabeled retinol added 
 to the reaction mix at 10 nm which roughly corresponds to the generally 
 recommended /10 of the kd concentration of radioligand .
the ic50 values 
 were calculated from the 12-point compound titrations using a four - parameter 
 logistic equation .
compounds with appreciable rbp4 binding potency 
 ( generally , with ic50 < 150 nm ) were further assessed 
 for the ability to antagonize the retinol - dependent rbp4-ttr interaction 
 using the htrf assay .
the ability of an analogue to disrupt the retinol - induced 
 interaction of rbp4 with ttr was examined using the previously described 
 htrf assay that probes retinol - dependent 
 rbp4-ttr interaction . as indicated in the experimental 
 section ,
we used bacterially expressed maltose binding protein 
 ( mbp ) tagged rbp4 and commercially available ttr labeled directly 
 with eu cryptate along with a d2-conjugated anti - mbp 
 monoclonal antibody in order to implement this assay .
retinol added 
 to the reaction mix at 1 m concentration stimulates rbp4-ttr 
 interaction which brings europium in proximity to the d2 dye with 
 the following fluorescence energy transfer ( fret ) to d2 .
the fret 
 signal , measured as a 668 nm emission , was normalized using the 620 
 nm europium emission to compensate for the pipetting and dispensing 
 errors . following a 12-point dose titration ( 20 m to 0.1 nm ) 

the ic50 values were calculated using a standard four - parameter 
 logistic nonlinear regression model equation . in order to monitor 
 a correlation between the binding affinity of compounds for rbp4 and 
 their potency as antagonists of the retinol - dependent rbp4-ttr interaction , 
 we tracked a ratio of ic50 values in the htrf and spa assays . 
 despite the difference in binding potency , for the majority of analogues , 
 this ratio tended to be within the 520 range .
table 1 summarizes efforts 
 to replace the carboxylic acid 
 moiety of a1120 with an acylsulfonamide appendage .
the docking of 
 analogues 911 within our model indicated 
 favorable geometric alignment within the rbp4 binding cavity and engagement 
 in critical h - bond interactions , with the acylsulfonamide appendages 
 projecting out of the binding cavity toward solvent ( figure 5 ) .
however , these analogues exhibited a substantial 
 reduction in potency ( 20-fold or greater ) relative to a1120 in both 
 the spa and htrf assays .
this loss may be partially attributed to 
 significant binding penalties incurred by solvent exposure of the 
 hydrophobic acylsulfonamide residues .
interestingly , the htrf ic50 values improved slightly with increasing size of the acylsulfonamide 
 appendage , which may suggest that the larger moieties could be projecting 
 into the rbp4-ttr interaction interface in a similar fashion as fenretinide , 
 thereby potentially hindering complexation between the two proteins . ( a )
overlay 
 of glide docked poses of analogues 9 ( green ) , 10 ( yellow ) , 11 ( orange ) , and a1120 ( magenta ) 
 within the rbp4 binding cavity using 3fmz .
analogues 911 are shown extending through the cavity in similar fashion 
 to a1120 , with the acylsulfonamide and carboxamido moieties engaging 
 in h - bond interactions with arg121 , gln98 , tyr90 , and leu37 ( both 
 not shown ) , respectively . contacting
( c ) legend for the ligand interaction diagram in the binding 
 pose using moe .
to further probe the 
 rbp4-arylcarboxylic acid binding region , we 
 explored the potency effects of replacing the anthranilic acid fragment 
 with aliphatic carboxylic acids . to that end ,
the acylic oxoacids 1214 and racemic proline analogue ( )-15 were prepared ; however , these compounds also exhibited 
 significantly reduced potency .
it is possible that less than optimal 
 positioning of the carboxylic acid within the binding cavity , perhaps 
 in combination with diminished interactions with phe96 , contributed 
 to the weak potency values observed for these analogues .
the precipitous 
 drop in rbp4 potency observed for this small sample set of analogues , 
 in addition to the potency results obtained for the aforementioned 
 acysulfonamides , prompted us to explore other changes to the scaffold 
 while keeping the anthranilic carboxylic acid appendage intact .
ic50 values for the spa 
 assay obtained in the presence of a fixed , 10 nm concentration of h - retinol .
ic50 values for the htrf 
 assay obtained in the presence of 1 m concentration of retinol .
data represent the mean of 
 at least 
 two independent experiments run in duplicate .
acknowledging the fact that the poor hlm stability 
 observed for a1120 could be due in part to the piperidine ring presenting 
 potential metabolic soft spots for cyp - mediated oxidation , we explored 
 replacing it with alternative scaffolds in an attempt to probe structural 
 changes that could provide suitable rbp4 antagonist activity with 
 an improved metabolic profile .
drawing from the patent literature , a series of analogues were initially prepared 
 whereby the piperidine ring was replaced with an acyclic n - methyl - n-(2-phenoxyethyl)amido linker in order 
 to impart greater conformational flexibility ( table 2 ) .
the complementary o - trifluoromethylphenyl 
 substituted analogue 20 was found to be significantly 
 less potent than a1120 ( 100-fold ) , presumably because of an 
 entropic penalty incurred by the two additional rotatable bonds of 
 the acyclic linkage .
however , the o - tert - butylphenyl analogue 25 exhibited dramatically improved 
 potency in the spa and hrtf assays relative to 20 ( spa 
 ic50 = 64.8 nm and htrf ic50 = 0.554 m ) . 

this observation may be attributed to partial compensation of the 
 entropic penalty incurred via increased van der waals contacts between 
 the bulkier and more lipophilic tert - butyl group 
 and the hydrophobic surface of the -ionone pocket within the 
 rbp4 binding cavity .
our docking model showed a good overlay between 25 and a1120 , with its carboxylic acid engaged in the key 
 hydrogen bond interactions with tyr90 , gln98 , arg121 , and leu37 ( figure 6 ) . despite the encouraging rbp4 potency observed 
 for antagonist 25 ,
poor liver microsomal stability across 
 multiple species was identified as a major liability . the observed 

poor microsomal stability was presumed to be due to extensive cyp - mediated 
 oxidation of the metabolically labile tert - butyl 
 group and/or the acyclic linkage .
thus , this series was deprioritized , 
 and the team focused its efforts on analogues with more conformationally 
 restricted core scaffolds that might be less susceptible to cyp - mediated 
 oxidation and not require the presence of the metabolically labile o - tert - butylphenyl group to achieve favorable rbp4 binding 
 affinity .
overlay of minimized bound conformations of rbp4 antagonist 25 ( green ) and a1120 ( magenta ) within 3fmz .
analogue 25 is shown extending through the cavity in similar fashion 
 to a1120 , with its carboxylic acid engaging in h - bond interactions 
 with arg121 , gln98 , and tyr90 ( not shown ) and with carboxamide carbonyl 
 interacting with leu37 ( not shown ) .
ic50 values for the spa 
 assay obtained in the presence of a fixed , 10 nm concentration of h - retinol .
ic50 values for the htrf 
 assay obtained in the presence of 1 m concentration of retinol .
data represent the mean of 
 at least 
 two independent experiments run in duplicate .
additional analogues that contained novel conformationally 
 restricted cores that linked together the o - trifluoromethylphenyl 
 and arylcarboxylic acid fragments were investigated ( table 3 ) .
in addition to the aforementioned goal of developing 
 a ligand that was less susceptible to cyp - mediated oxidative metabolism , 
 conformationally restricted cores of varying geometry were also explored 
 so as to probe putative bioactive binding conformations that could 
 potentially lead to analogues with enhanced rbp4 binding affinity . 
 within the set of compounds tested , the bicyclic { 3.3.0}-octahydrocyclopenta[c]pyrrolo analogues 43 and ( )-45 emerged as potent rbp4 antagonists ( spa ic50 of 72.7 
 and 148.5 nm , respectively ; htrf ic50 of 0.294 and 0.481 
 m , respectively ) .
ic50 values for the spa 
 assay obtained in the presence of a fixed , 10 nm concentration of h - retinol .
ic50 values for the htrf 
 assay obtained in the presence of 1 m concentration of retinol .
data represent the mean of 
 at least 
 two independent experiments run in duplicate .
docking analysis of the active endo - isomer 43 shows favorable alignment within 
 the rbp4 binding cavity 
 ( figure 7 ) .
the bicyclic { 3.3.0}-octahydrocyclopenta[c]pyrrolo core is shown extending through the -barrel 
 with the o - trifluoromethylphenyl ring extending slightly 
 farther into the hydrophobic -ionone cavity than a1120 , and 
 the anthranilic carboxylic appendage is engaged in key h - bond interactions . 

interestingly , exo - isomer 48 also exhibited 
 a favorable geometric pose within the model ; however the compound 
 was found to be devoid of rbp4 activity ( spa ic50 > 
 3 m ) . 

in an attempt to reconcile the discrepancies between the docking experiments 
 and the spa binding affinities observed for these two geometric isomers , 
 free energy differences associated with minimized bound ( docked pose ) 
 and unbound ligand conformations were calculated using macromodel 
 ( version 9.9 , schrdinger , llc . ) for both compounds .
indeed , 
 it was determined that the exo - isomer 48 adopts a more strained bound geometry relative to endo - isomer 43 ( 2 kcal / mol greater energy , data 
 not shown ) in order to optimize binding interactions with rbp4 .
while 
 these calculations ignore many other possible effects , they offer 
 a possible explanation for the higher rbp4 binding affinity observed 
 for endo - isomer 43 .
overlay of minimized 
 bound conformations of endo - isomer 43 ( cyan ) , exo - isomer 48 ( orange ) , and 
 a1120 ( magenta ) within 3fmz . contacting residues 

are labeled and illustrated in stick format . in vitro pharmacological evaluation of 43 revealed 
 a desirable profile that included no significant off - target activity 
 at the herg channel or within a standard screening panel of 55 gpcrs , 
 enzymes , ion channels , and transporters .
in addition , 43 exhibited good solubility and metabolic stability , including significantly 
 improved hlm stability ( table 4 ) .
the compound 
 did , however , present submicromolar inhibitory activity for cyp2c9 
 ( ic50 = 340 nm ) .
thus , a limited set of follow - up analogues 
 was generated in an attempt to diminish cyp2c9 activity and further 
 improve rbp4 potency .
we initially explored the sar impact of an electron 
 withdrawing or donating group substituted para to the urea on the 
 arylcarboxylic acid phenyl ring ( 5053 ) .
fluorinated analogue 50 presented spa potency levels 
 comparable to 43 ( spa ic50 = 88.8 nm and htrf 
 ic50 = 0.285 m ) with moderate hlm stability ; however , 
 cyp2c9 activity did not improve ( ic50 = 333 nm ) .
similarly , 
 chlorinated analogue 52 also exhibited undesirable potency 
 at cyp2c9 ( ic50 = 548 nm ) with a concomitant 4-fold diminishment 
 in rbp4 spa potency relative to 43 ( spa ic50 = 328.8 nm and htrf ic50 = 0.340 m ) .
substitution 
 with either methoxy ( 51 ) or methylsulfonyl ( 53 ) did lead to diminished cyp2c9 activity ( ic50 of 13 and 
 8.7 m , respectively ) ; however , the compounds were also significantly 
 less potent for rbp4 .
interestingly , replacing the arylcarboxylic 
 acid phenyl ring of 43 with either a pyridine or pyridazine 
 moiety had a dramatic impact on rbp4 binding affinity for the series . 

it was initially found that the position of the pyridine nitrogen 
 was critical for rbp4 activity , as the 2-aminopyridyl analogue 54 was essentially devoid of activity while the 4-aminopyridyl 
 analogue 55 exhibited rbp4 potency comparable to a1120 
 ( spa ic50 = 18.7 nm and htrf ic50 = 0.179 m ) . 

unfortunately , pyridine 55 was found to be a potent cyp3a4 
 inhibitor ( ic50 < 46 nm ) ; therefore , we sought to mitigate 
 this liability by introducing a methyl group ortho to the pyridyl 
 nitrogen ( 56 ) .
indeed , analogue 56 exhibited 
 diminished affinity for cyp3a4 ( ic50 = 1.1 m ) . in 
 addition , 56 also exhibited improved activity at cyp2c9 
 ( ic50 = 1 m ) relative to 43 , exhibited 
 comparable potency to a1120 in the spa assay ( spa ic50 = 
 23.9 nm ) , and was within a 2-fold potency range of a1120 in the htrf 
 assay ( htrf ic50 = 0.235 m ) .
lastly , we found that 
 replacing the methylpyridine of 43 with a pyridazine 
 ring ( 57 ) further improved activity at cyp3a4 ( ic50 = 12 m ) and cyp2c9 ( ic50 = 17 m ) , 
 provided an overall favorable adme profile ( including excellent hlm 
 stability ) , and yielded an rbp4 antagonist of comparable potency to 
 a1120 in both the spa and htrf assays ( spa ic50 = 24.0 
 nm and htrf ic50 = 0.121 m ) .
ic50 values for the spa 
 assay obtained in the presence of a fixed , 10 nm concentration of h - retinol .
ic50 values for the htrf 
 assay obtained in the presence of 1 m concentration of retinol .
data represent the mean of 
 at least 
 two independent experiments run in duplicate .
compound 
 concentration was 10 m , and incubation time with the microsomes 
 was 30 min , h = human .
cyp ic50 determined via 
 fluorescence detection and with inhibitors sulfaphenazole ( cyp2c9 ) , 
 tranylcypromine ( cyp2c19 ) , quinidine ( cyp2d6 ) , and ketoconazole ( cyp3a4 ) . 

the 
 superior rbp4 binding affinity of heteroaromatic analogues 5557 relative to 43 and 5053 prompted us to explore our computational 
 model and examine if enhanced  edge - to - face 
 interactions with phe96 could be playing a role in the observed potency 
 trends .
we conducted ab initio molecular orbital calculations using 
 a simplified model derived from the docked poses of 43 , 50 , 56 , and 57 to identify 
 changes in the electronic distribution of the aromatic and heteroaromatic 
 rings bearing the carboxylic acid and to generate phe96 interaction 
 scores for each analogue . as expected , the more polarizable heteroaromatic 
 analogues 56 and 57 presented enhanced phe96 
 interaction scores relative to 43 and 50 ( table 5 ) .
the enhanced polarization of the 
 ring system is indicated by the ab initio derived partial charges 
 at the point of substitution .
the increased negative charge of the 
 -system of the ligand is expected to interact favorably with 
 the c 
h atoms of f96 in the predicted edge - to - face geometry . 
 increased negative charge and the f96 interaction score roughly parallel 
 the increase in activity .
these results could indicate that the  
 edge - to - face interactions between the heteroaromatic systems of 5557 and phe96 are stronger relative 
 to the nonheteroaromatic analogues , potentially 
 leading to the enhanced binding affinities and htrf antagonist activity 
 observed for these analogues .
the aromatic / heteroaromatic ring 
 electronic distribution for each analogue was derived from ab initio 
 molecular orbital calculations performed on simplified docking pose 
 models .
the anthranilic 
 motif for each compound 
 was preserved for computational efficiency , and phe96 was modeled 
 as simply the single amino acid with all other protein atoms removed .
centroid distance is the distance 
 between the phe96 ch and the aromatic or heteroaromatic ring of the 
 rbp4 ligand within the rbp4 binding cavity . to further probe the rbp4 arylcarboxylic acid binding 
 region of 43
, we explored a limited set of amino acid 
 based analogues 
 ( table 6 ) . the glycinergic analogue 58 exhibited weak potency in both the spa and htrf assays compared 
 to 43 .
interestingly , an enantiopreference for the ( s)-isomers was observed for chiral analogues 5962 . the eudismic ratio for ( s)-59 and its congener ( r)-60 was 1.7 for the htrf assay , and the eudismic ratios for 
 ( s)-61 and ( r)-62 was 10 for both the spa and htrf assays , respectively . 

our model suggests that the enantiopreference and 
 superior potency of ( s)-61 may be partially 
 attributed to optimal positioning of its carboxylic acid to allow 
 for better engagement with arg121 , tyr90 , and gln98 relative to ( r)-62 , as ( r)-62 must adopt a higher energy conformation in order for its carboxylic 
 acid to engage in h - bonding interactions with these residues . in addition , 
 the positioning of the phenyl ring of ( s)-61 brings it within closer proximity to phe96 than ( r)-62 . this closer proximity to phe96 could present a 
 stronger  edge - to - face interaction ( as evidenced 
 by the f96 interaction scores ) , which could further contribute to 
 the enantiopreference observed between ( s)-61 and ( r)-62 . in both compounds , 
 the calculated charges of the closest approaching carbon atoms are 
 0.10 for ( s)-61 and 0.16 for ( r)-62 .
the more positive charges suggest that 
 the edge - to - face interaction is weaker for both compounds than those 
 in table 5 but that ( s)-61 would more favorably interact than ( r)-62 .
ic50 values for the spa 
 assay obtained in the presence of a fixed , 10 nm concentration of h - retinol .
ic50 values for the htrf 
 assay obtained in the presence of 1 m concentration of retinol .
data represent the mean of 
 at least 
 two independent experiments run in duplicate .
the anthranilic motif for each compound 
 was preserved for computational efficiency , and phe96 was modeled 
 as simply the single amino acid with all other protein atoms removed .
centroid distance is the distance 
 between phe96 ch and the aromatic or heteroaromatic ring of the rbp4 
 ligand . the favorable in 
 vitro rbp4 potency and adme profile of 43 prompted us 
 to evaluate the compound in rodent acute and chronic 
 dosing pharmacokinetic ( pk ) and pharmacodynamic ( pd ) experiments . 
 following iv administration of 0.5 mg / kg ,
43 was slowly 
 eliminated from plasma with a mean apparent terminal phase elimination 
 half - life of 10.3 h. the estimated total body clearance of 43 was low ( mean , 35.3 ml h kg ) , and the estimated apparent volume of distribution at steady state 
 was small ( mean , 523 ml / kg ) .
these data are suggestive of a slow rate 
 of metabolism / elimination and limited extravascular distribution of 
 the compound .
no unchanged 43 was quantifiable in urine 
 samples collected between 0 and 48 h after iv administration of the 
 compound . following po administration of 5 mg / kg as a single 
 dose on day 
 0 , a mean peak plasma concentration of 43 of 3950 ng / ml 
 and an aucinf of 43  898 hng / ml were observed 
 ( table 7 ) .
the oral bioavailability of 43 after dosing on day 0 , as estimated from aucinf values , was 31% . for rats given a single daily po dose for 6 consecutive 
 days , plasma concentrations of 43 prior to dosing on 
 day 6 ( i.e. , approximately 24 h after administration of the previous 
 dose ) ranged from 243 to 453 ng / ml . following dose administration 
 on day 6 ,
mean peak plasma concentrations of 43 and aucinf were slightly higher than observed on day 0 .
apparent half - life of the terminal 
 phase of elimination of 43 from plasma .
area under the plasma concentration 
 versus time curve from 0 to the last time point 43 was 
 quantifiable in plasma .
bioavailability : f = ( aucinfpo  doseiv )  
 aucinfiv  dosepo ) .
dosing groups consisting of three 
 drug naive adult male sprague  dawley rats , dosed once on day 
 0 .
dosing group consisting 
 of three 
 drug naive adult male sprague  dawley rats , dosed q.d . from 
 day 0 to day 6 .
earliest 
 sample collection time 
 point . in order to demonstrate 
 the in vivo target engagement ,
pd correlations , 
 we studied the effect of 43 dosing in rats on the level 
 of plasma rbp4 .
aliquots of plasma samples collected during the acute 
 and chronic dosing pk experiments were used to analyze plasma rbp4 
 concentrations as we previously described . after a single 5
mg / kg oral dose of 43 , a 3050% 
 decrease in plasma rbp4 was observed ( data not shown ) , while the 7-day 
 oral administration in rats at 5 mg / kg induced an approximately 60% 
 reduction in plasma rbp4 ( figure 8a ) .
comparison 
 of the dynamics of rbp4 lowering in response to 43 treatment 
 ( figure 8a ) with plasma compound levels ( figure 8b ) shows a good correlation between the reduction 
 in plasma rbp4 and increase in compound concentration .
given the absolute 
 correlation between rbp4 lowering and bisretinoid reduction in the abca4 mouse 
 model of enhanced retinal lipofuscinogenesis , which we and others 
 previously established for the antagonists of the rbp4-ttr interaction 
 from different structural classes , it seems reasonable 
 to expect that 43 and similar analogues with good rbp4 
 lowering potency will show the desired preclinical efficacy in the abca4 mice .
correlation 
 between the rbp4 ( a ) and 43 ( b ) plasma 
 levels after administration of the seventh oral 5 mg / kg dose of 43 in rats .
a1120 
 is a potent , nonretinoid rbp4 antagonist ( spa ic50 = 14.8 
 nm and htrf ic50 = 155.5 nm ) that induces significant 
 lowering of serum rbp4 levels in vivo and has exhibited efficacy in 
 a preclinical rodent model of excessive lipofuscin accumulation in 
 the rpe . despite its attractive profile , further development of a1120 
 as a potential therapeutic to treat dry amd
is hampered by the compound s 
 poor hlm stability ( 3% remaining after a 30 min incubation 
 time ) .
therefore , using a1120 as a template , we sought to explore 
 various structural changes that could provide an novel rbp4 antagonist 
 of comparable potency but with improved hlm stability .
we investigated 
 several modifications , beginning with the acylsulfonamide 
 carboxylic acid isosteres 911 and 
 the aliphatic carboxylic acids 12()-15 .
this set of analogues did not yield potent antagonists , 
 and our program quickly shifted focus on modifying the core while 
 keeping the anthranilic acid appendage intact .
several structural 
 modifications were made to the core , whereby 
 the piperidine ring was replaced with an acyclic and various conformationally 
 constrained motifs . among the novel rbp4 antagonists identified , the 
 bicyclic { 3.3.0}-octahydrocyclopenta[c]pyrrolo rbp4 
 antagonist 43 exhibits potent in vitro rbp4 spa ( ic50 = 73 nm ) and htrf ( ic50 = 294 nm ) assay activity 
 that is comparable to a1120 .
the compound also possesses a favorable 
 adme profile with excellent hlm stability ( 100% remaining after a 
 30 min incubation time ) and no limiting off - target pharmacology with 
 the exception of cyp2c9 inhibitory activity ( ic50 = 340 
 nm ) .
furthermore , compound 43 possesses good pk and pd 
 properties , leading to a robust and sustained lowering ( > 85% ) of 
 serum 
 rbp4 levels in both acute and chronic rodent oral dosing studies .
additional work within the bicyclic { 3.3.0}-octahydrocyclopenta[c]pyrrolo series led to the discovery of pyridazine 57 , which exhibited potent in vitro rbp4 antagonist activity 
 ( spa ic50 = 24 nm and htrf ic50 = 121 nm ) , favorable 
 adme profiles , and improved activity at cyp2c9 ( ic50 = 
 17 m ) .
encouraged by these results , we have continued to focus 
 our efforts within the bicyclic { 3.3.0}-octahydrocyclopenta[c]pyrrolo series .
additional refinements have led to rbp4 
 antagonists possessing exquisite in vitro potency , robust in vivo 
 serum rbp4 lowering capability , and efficacy in the abca4 mouse model .
all reactions were performed under 
 a dry atmosphere of nitrogen unless otherwise specified . indicated 
 reaction temperatures refer to the reaction bath , while room temperature 
 ( rt )
commercial grade reagents and anhydrous 
 solvents were used as received from vendors , and no attempts were 
 made to purify or dry these components further .
3-(2-(trifluoromethyl)phenyl)azetidine 
 hydrochloride was purchased from small molecules [ cas number 1203684 - 79 - 0 ] . 

2,3,4,5-tetrahydro-1h - benzo[d]azepine 
 was purchased from acros [ cas number 4424 - 20 - 8 ] .
tert - butyl 2,6-diazaspiro[3.3]heptane-2-carboxylate hemioxalate was purchased 
 from alfa [ cas number 1041026 - 71 - 4 ] .
2,3-dihydrospiro[indene-1,4-piperidine ] 
 hydrochloride was purchased from matrix scientific [ cas number 96651 - 85 - 3 ] . 

removal of solvents under reduced pressure was accomplished with a 
 buchi rotary evaporator at approximately 28 mmhg pressure using a 
 teflon - linked knf vacuum pump .
visualization of tlc plates was made by observation 
 with short wave uv light ( 254 nm lamp ) , 10% phosphomolybdic acid in 
 ethanol or in iodine vapors .
preparative thin layer chromatography 
 was performed using analtech , 20 cm  20 cm , 1000 m preparative 
 tlc plates .
flash column chromatography was carried out using a teledyne 
 isco combiflash companion unit with redisep rf silica gel columns . 
 if needed , products were purified by reverse phase chromatography , 
 using a teledyne isco combiflash companion unit with redisep gold 
 c18 reverse phase column .
proton nmr spectra were obtained on either 
 a 300 mhz bruker nuclear magnetic resonance spectrometer or a 500 
 mhz bruker nuclear magnetic resonance spectrometer .
chemical shifts 
 (  ) are reported in parts per million ( ppm ) , and coupling constant 
 ( j ) values are given in hz , with the following spectral 
 pattern designations : s , singlet ; d , doublet ; t , triplet ; q , quartet ; 
 dd , doublet of doublets ; m , multiplet ; br , broad .
melting points are uncorrected 
 and were obtained using a mel - temp electrothermal melting point apparatus . 

mass spectroscopic analyses were performed using positive mode electron 
 spray ionization ( esi ) on a varian prostar lc 
high pressure liquid chromatography ( hplc ) purity 
 analysis was performed using a varian prostar hplc system with a binary 
 solvent system a and b using a gradient elusion [ a , h2o 
 with 0.05% trifluoroacetic acid ( tfa ) ; b , ch3cn with 0.05% 
 tfa ] and flow rate of 1 ml / min , with uv detection at 223 nm . all final 
 compounds were purified to 95% purity by the varian prostar 
 hplc system using the following methods : ( a ) phenomenex c18(2 ) column 
 ( 3.0 mm  250 mm ) ; mobile phase , a = h2o with 0.05% 
 tfa and b = ch3cn with 0.05% tfa ; gradient , 090% 
 b ( 0.020.0 min ) ; ( b ) pursuit xrs c18 column ( 4.6 mm  
 250 mm ) ; mobile phase , a = h2o with 0.05% tfa and b = ch3cn with 0.05% tfa ; gradient , 090% b ( 0.015.0 
 min ) ; ( c ) sunfire c18 5 m ( 4.6 mm  250 mm ) , mobile phase , 
 a = h2o with 0.05% tfa and b = ch3cn with 0.05% 
 tfa ; gradient , 0100% b ( 0.020.0 min ) .
step a. to a solution of 
 1-bromo-2-(trifluoromethyl)benzene ( 4 , 35.0 g , 156 mmol ) 
 in thf ( 350 ml ) cooled to 78 c was slowly added a solution 
 of n - buli ( 70.4 ml , 2.5 m in thf , 176 mmol ) over 
 a period of 15 min .
the mixture was stirred at 78 c 
 for 40 min , was allowed to warm to 0 c and then cooled back 
 to 78 c . to this
was added a solution of 1-benzylpiperidin-4-one 
 ( 22.1 g , 117 mmol ) in thf ( 80 ml ) over a period of 10 min .
the resulting 
 mixture continued to stir at 78 c for 2 h. the reaction 
 was carefully quenched with aqueous , saturated nh4cl solution 
 ( 500 ml ) , and the mixture was extracted with etoac ( 300 ml ) .
the organic 
 extract was washed with h2o , brine , dried over na2so4 , filtered , and concentrated under reduced pressure . 

the resulting residue was chromatographed over silica gel ( isco combiflash 
 companion unit , 330 g redisep column , 030% etoac in hexanes ) 
 to give 1-benzyl-4-(2-(trifluoromethyl)phenyl)piperidin-4-ol 
 ( 5 ) as a light - yellow oil ( 29.2 g , 74% ) : h nmr ( 500 mhz , cdcl3 )  7.78 ( d , j = 1.6 hz , 1h ) , 7.59 ( m , 1h ) , 7.47 ( m , 1h ) , 7.36 ( m , 5h ) , 7.31 ( m , 
 2h ) , 3.58 ( s , 2h ) , 2.80 ( m , 2h ) , 2.55 ( m , 2h ) , 2.27 ( m , 2h ) , 1.88 
 ( m , 2h ) ; esi ms m / z 336 [ m + h ] . step b. a 0 c cooled solution 
 of 1-benzyl-4-(2-(trifluoromethyl)phenyl)piperidin-4-ol 
 ( 5 , 29.2 g , 87.1 mmol ) in thionyl chloride ( 60 ml ) stirred 
 for 2 h and was then diluted with ch2cl2 ( 250 
 ml ) .
the mixture was carefully poured into a solution of aqueous , 
 saturated nahco3 solution ( 200 ml ) .
the biphasic mixture 
 was separated , and the aqueous layer was further extracted with ch2cl2 ( 400 ml ) .
the combined organic layers were 
 washed with brine , dried over na2so4 , filtered , 
 and concentrated .
the resulting residue was chromatographed over silica 
 gel ( isco combiflash companion unit , 330 g redisep column , 030% 
 etoac in hexanes ) to give 1-benzyl-4-(2-(trifluoromethyl)phenyl)-1,2,3,6-tetrahydropyridine 
 ( 6 ) as a light - yellow oil ( 13.5 g , 49% ) : h nmr ( 500 mhz , cdcl3 )  7.63 ( d , j = 1.6 hz , 1h ) , 7.48 ( m , 1h ) , 7.39 ( m , 5h ) , 7.28 ( m , 2h ) , 5.56 ( s , 
 1h ) , 0.68 ( s , 2h ) , 3.14 ( m , 2h ) , 2.70 ( m , 2h ) , 2.39 ( m , 2h ) ; esi ms m / z 318 [ m + h ] .
step c. a mixture of 1-benzyl-4-(2-(trifluoromethyl)phenyl)-1,2,3,6-tetrahydropyridine 
 ( 6 , 13.6 g , 42.5 mmol ) , 10% pd / c ( 3.0 g ) , and ammonium 
 formate ( 26.8 g , 425 mmol ) in ch3oh ( 800 ml ) was heated 
 at reflux for 2 h. the mixture cooled to rt and was filtered over 
 celite .
the filtrate was concentrated and the resulting residue was 
 chromatographed over silica gel ( isco combiflash companion unit , 330 
 g redisep column , 010% ch3oh with 1% nh4oh in ch2cl2 ) to give 4-(2-(trifluoromethyl)phenyl)piperidine 
 as a colorless oil ( 2.0 g , 21% ) : h nmr ( 500 mhz , cdcl3 )  7.61 ( d , j = 1.7 hz , 1h ) , 7.52 
 ( m , 2h ) , 7.29 ( m , 1h ) , 3.21 ( m , 2h ) , 3.07 ( m , 1h ) , 2.80 ( m , 2h ) , 2.33 
 ( bs , 1h ) , 1.77 ( m , 4h ) ; esi ms m / z 230 [ m + h ] . to a solution of 4-(2-(trifluoromethyl)phenyl)piperidine 
 ( 5.6 g , 24.5 mmol ) in ch3cn ( 30 ml ) was added a 4 m solution 
 of hcl in 1,4-dioxane ( 6.1 ml , 24.5 mmol ) at rt .
the mixture stirred 
 for 2 h and was then concentrated under reduced pressure to give 4-(2-(trifluoromethyl)phenyl)piperidine 
 hydrochloride ( 7 ) as a white solid ( 6.4 g , > 99% ) : 
 esi 
 ms m / z 230 [ m + h ] .
step d. a mixture of 4-(2-(trifluoromethyl)phenyl)piperidine 
 hydrochloride ( 7 , 7.89 g , 29.7 mmol ) and methyl 2-isocyanatobenzoate 
 ( 5.27 g , 29.7 mmol ) in ch2cl2 ( 50 ml ) was stirred 
 for 2 h and then chromatographed over silica gel ( 025% etoac 
 in hexanes ) to give methyl 2-(4-(2-(trifluoromethyl)phenyl)piperidine-1-carboxamido)benzoate 
 as a white solid ( 8.27 g , 77% ) .
to a solution of 2-(4-(2-(trifluoromethyl)phenyl)piperidine-1-carboxamido)benzoate 
 ( 8.0 g , 19.6 mmol ) in ch3oh ( 50 ml ) and thf ( 50 ml ) was 
 added naoh ( 2 n , 20 ml ) .
the mixture was stirred at rt for 2 h , was 
 diluted with h2o ( 100 ml ) , and then was acidified to ph 
 6 with 2 n hcl .
the mixture was extracted with ch2cl2 ( 3  150 ml ) , and the organic extracts were dried over 
 na2so4 , filtered , and concentrated .
the residue 
 was chromatographed over silica gel ( 05% ch3oh 
 in ch2cl2 ) to give 2-(4-(2-(trifluoromethyl)phenyl)piperidine-1-carboxamido)benzoic 
 acid ( a1120 ) ( 3 ) as a white solid ( 7.3 g , 95% ) .
mp 156158 
 c ; h nmr ( 300 mhz , cdcl3 )  10.68 
 ( s , 1h ) , 8.59 ( d , j = 8.6 hz , 1h ) , 8.05 ( dd , j = 8.1 , 1.6 hz , 1h ) , 7.587.53 ( m , 1h ) , 7.37 ( dd , j = 7.4 , 1.6 hz , 1h ) , 7.257.12 ( m , 3h ) , 7.026.96 
 ( m , 1h ) , 4.40 ( m , 2h ) , 3.503.40 ( m , 1h ) , 3.062.97 
 ( m , 2h ) , 1.901.80 ( m , 4h ) ; esi ms m / z 393 [ m + h ] ; hplc 98.5% purity ( auc ) , tr = 12.5 min ( method a ) .
step 
 e. to a solution of 2-(4-(2-(trifluoromethyl)phenyl)piperidine-1-carboxamido)benzoic 
 acid ( 3 , 0.711 g , 1.81 mmol ) and i - pr2net ( 1.41 ml , 8.15 mmol ) in dmf ( 12.7 ml ) was added hatu ( 1.03 
 g , 2.72 mmol ) .
the mixture stirred at rt for 1.5 h and was then diluted 
 with aqueous saturated nh4cl ( 40 ml ) .
the aqueous mixture 
 was extracted with ch2cl2 ( 4  30 ml ) , 
 and the combined organic extracts were concentrated under reduced 
 pressure .
the resulting residue was chromatographed over silica gel 
 ( isco combiflash companion unit , 40 g redisep column , 025% 
 etoac in hexanes ) to give 7-(4-(2-(trifluoromethyl)phenyl)piperidine-1-carbonyl)-7-azabicyclo[4.2.0]octa-1(6),2,4-trien-8-one 
 ( 8) as a white solid ( 0.565 g , 83% ) : mp 127130 
 c ; h nmr ( 500 mhz , dmso - d6 )  7.91 ( d , j = 7.0 hz , 1h ) , 7.737.65 
 ( m , 3h ) , 7.647.59 ( m , 1h ) , 7.487.38 ( m , 1h ) , 7.23 
 ( d , j = 8.5 hz , 1h ) , 7.217.17 ( m , 1h ) , 4.534.44 
 ( m , 2h ) , 3.193.07 ( m , 3h ) , 1.921.80 ( m , 2h ) , 1.791.73 
 ( m , 2h ) ; esi ms m / z 375 [ m + h ] .
step f. to a 0 c solution of 
 methanesulfonamide 
 ( 0.057 g , 0.60 mmol ) in thf ( 1.0 ml ) was added nah ( 60% in mineral 
 oil , 0.024 g , 0.60 mmol ) , and the resulting solution was stirred at 
 0 c for 5 min and for an additional 15 min at rt .
a solution 
 of 8 ( 0.150 g , 0.40 mmol ) in thf ( 2.0 ml ) was added , 
 and the resulting solution was stirred at rt for 72 h. the reaction 
 was quenched with h2o and acidified to ph 4 with 2 n hcl . 

the resulting precipitate was collected by filtration and washed with 
 h2o ( 40 ml ) and hexanes ( 40 ml ) .
the obtained solids were 
 chromatographed over silica gel ( isco combiflash companion unit , 40 
 g redisep column , 05% ch3oh in ch2cl2 with 0.05% hoac ) to provide n-(2-((methylsulfonyl)carbamoyl)phenyl)-4-(2-(trifluoromethyl)phenyl)piperidine-1-carboxamide 
 ( 9 ) as a white solid ( 0.035 g , 18% ) : mp 220285 
 c ; h nmr ( 500 mhz , dmso - d6 )  12.03 ( br s , 1h ) , 9.76 ( s , 1h ) , 7.83 ( d , j = 7.5 hz , 1h ) , 7.707.60 ( m , 4h ) , 7.517.46 ( m , 1h ) , 
 7.447.39 ( m , 1h ) , 7.097.04 ( m , 1h ) , 4.23 ( d , j = 13.0 hz , 2h ) , 3.32 ( s , 3h ) , 3.123.04 ( m , 1h ) , 
 2.96 ( t , j = 11.5 hz , 2h ) , 1.831.68 ( m , 4h ) ; 
 esi ms m / z 468 [ m + h ] ; hplc > 99% purity ( auc ) , tr = 14.4 
 min 
 ( method c ) .
compound 10 was prepared according 
 to a similar procedure described for the synthesis of 9 .
mp 195208 c ; h nmr ( 500 mhz , dmso - d6 )  12.04 ( br s , 1h ) , 9.96 ( br s , 1h ) , 
 7.98 ( d , j = 8.5 hz , 1h ) , 7.737.66 ( m , 3h ) , 
 7.657.60 ( m , 1h ) , 7.547.48 ( m , 1h ) , 7.447.39 
 ( m , 1h ) , 7.097.04 ( m , 1h ) , 4.21 ( d , j = 13.0 
 hz , 2h ) , 3.143.03 ( m , 2h ) , 2.98 ( t , j = 12.0 
 hz , 2h ) , 1.841.68 ( m , 4h ) , 1.191.04 ( m , 4h ) ; esi ms m / z 494 [ m + h ] ; hplc > 99% 
 purity ( auc ) , tr = 11.4 min ( method a ) .
compound 11 was prepared according 
 to a similar procedure described for the synthesis of 9 .
mp 136141 c ; h nmr ( 500 mhz , dmso - d6 )  7.997.90 ( m , 3h ) , 7.727.63 
 ( m , 3h ) , 7.627.58 ( m , 1h ) , 7.567.49 ( m , 3h ) , 7.487.41 
 ( m , 2h ) , 7.066.99 ( m , 1h ) , 4.154.05 ( m , 2h ) , 3.082.98 
 ( m , 1h ) , 2.902.81 ( m , 2h ) , 1.671.55 ( m , 4h ) ; esi ms m / z 530 [ m + h ] ; hplc > 99% 
 purity ( auc ) , tr = 17.8 min ( method c ) .
step a. to a solution 
 of 4-(2-(trifluoromethyl)phenyl)piperidine hydrochloride ( 7 , 0.140 g , 0.612 mmol ) and et3n ( 0.171 ml , 1.22 
 mmol ) in ch2cl2 ( 4 ml ) was added ethyl 2-chloro-2-oxoacetate 
 ( 0.100 g , 0.73 mmol ) at 0 c .
the mixture stirred at rt for 16 
 h and was concentrated under reduced pressure .
the residue was chromatographed 
 over silica gel ( 025% etoac in hexanes ) to give ethyl 2-oxo-2-(4-(2-(trifluoromethyl)phenyl)piperidin-1-yl)acetate 
 as a thick oil ( 0.190 g , 94% ) : h nmr ( 300 mhz , cdcl3 )  7.64 ( d , j = 7.9 hz , 1h ) , 7.54 
 ( t , j = 7.6 hz , 1h ) , 7.42 ( d , j = 
 7.8 hz , 1h ) , 7.33 ( t , j = 7.7 hz , 1h ) , 4.724.67 
 ( m , 1h ) , 4.37 ( q , j = 7.2 hz , 2h ) , 3.833.77 
 ( m , 1h ) , 3.293.18 ( m , 2h ) , 2.842.75 ( m , 1h ) , 1.921.67 
 ( m , 4h ) , 1.39 ( t , j = 7.1 hz , 3h ) ; esi ms m / z 330 [ m + h ] .
step b. to a solution of ethyl 2-oxo-2-(4-(2-(trifluoromethyl)phenyl)piperidin-1-yl)acetate 
 ( 0.190 g , 0.57 mmol ) in ch3oh ( 2 ml ) and thf ( 2 ml ) was 
 added naoh ( 2 n , 2 ml ) .
the mixture was stirred for 16 h , was diluted 
 with h2o ( 25 ml ) , and was acidified to ph 4 with 2 n hcl . 

the mixture was extracted with ch2cl2 ( 30 ml ) , 
 and the organic extracts were dried over na2so4 , filtered , and concentrated .
the residue was chromatographed over 
 silica gel ( 015% ch3oh in ch2cl2 ) to give 2-oxo-2-(4-(2-(trifluoromethyl)phenyl)piperidin-1-yl)acetic 
 acid ( 12 ) as a white solid ( 0.035 g , 20% ) : mp 193196 
 c ; h nmr ( 500 mhz , dmso - d6 )  7.697.55 ( m , 3h ) , 7.42 ( d , j = 
 7.6 hz , 1h ) , 4.43 ( m , 1h ) , 3.96 ( m , 1h ) , 3.07 ( br s , 2h ) , 2.64 ( br 
 s , 1h ) , 1.691.55 ( m , 4h ) ; esi ms m / z 300 [ m  h ] ; hplc > 99% purity 
 ( auc ) , tr = 15.7 min ( method c ) .
step a. to a solution 
 of 4-(2-(trifluoromethyl)phenyl)piperidine hydrochloride ( 7 , 0.130 g , 0.56 mmol ) and et3n ( 0.157 ml , 1.13 
 mmol ) in ch2cl2 ( 10 ml ) was added methyl 3-chloro-3-oxopropanoate 
 ( 0.077 g , 0.567 mmol ) at 0 c .
the mixture stirred at rt for 
 16 h and was concentrated under reduced pressure .
the residue was 
 chromatographed over silica gel ( 040% etoac in hexanes ) to 
 give methyl 3-oxo-3-(4-(2-(trifluoromethyl)phenyl)piperidin-1-yl)propanoate 
 ( 0.134 g , 71% ) : h nmr ( 500 mhz , cdcl3 )  
 7.63 ( d , j = 7.9 hz , 1h ) , 7.53 ( t , j = 7.5 hz , 1h ) , 7.40 ( d , j = 7.8 hz , 1h ) , 7.32 ( t , j = 7.7 hz , 1h ) , 4.854.78 ( m , 1h ) , 3.903.84 
 ( m , 1h ) , 3.78 ( s , 3h ) , 3.603.49 ( m , 2h ) , 3.283.14 
 ( m , 2h ) , 2.752.65 ( m , 1h ) , 1.891.64 ( m , 4h ) ; esi ms m / z 330
step b. to a solution of methyl 3-oxo-3-(4-(2-(trifluoromethyl)phenyl)piperidin-1-yl)propanoate 
 ( 0.134 g , 0.40 mmol ) in ch3oh ( 2 ml ) and thf ( 2 ml ) was 
 added naoh ( 2 n , 2 ml ) .
the mixture was stirred for 16 h , diluted 
 with h2o ( 25 ml ) , and acidified to ph 4 with 2 n hcl .
the 
 mixture was extracted with ch2cl2 ( 30 ml ) , and 
 the organic extracts were dried over na2so4 and 
 concentrated to give 3-oxo-3-(4-(2-(trifluoromethyl)phenyl)piperidin-1-yl)propanoic 
 acid ( 13 ) as a white solid ( 0.100 g , 78% ) : mp 112114 
 c ; h nmr ( 500 mhz , cdcl3 )  14.24 
 ( br s , 1h ) , 7.66 ( d , j = 7.8 hz , 1h ) , 7.54 ( t , j = 7.6 hz , 1h ) , 7.387.32 ( m , 2h ) , 4.84 ( m , 1h ) , 
 3.93 ( m , 1h ) , 3.42 ( m , 2h ) , 3.273.21 ( m , 2h ) , 2.832.77 
 ( m , 1h ) , 1.991.93 ( m , 2h ) , 1.761.66 ( m , 2h ) ; esi ms m / z 314 [ m  h ] ; hplc > 99% purity ( auc ) , tr = 15.5 
 min 
 ( method c ) .
a mixture of 4-(2-(trifluoromethyl)phenyl)piperidine 
 hydrochloride ( 7 , 0.100 g , 0.43 mmol ) and dihydrofuran-2,5-dione 
 ( 0.048 g , 0.48 mmol ) in ch2cl2 ( 8 ml ) was heated 
 at reflux for 4 h and then cooled to rt and concentrated under reduced 
 pressure .
the resulting residue was chromatographed over silica gel 
 ( 030% etoac in hexanes ) to give 4-oxo-4-(4-(2-(trifluoromethyl)phenyl)piperidin-1-yl)butanoic 
 acid ( 14 ) as a white solid ( 0.134 g , 93% ) : mp 138140 
 c ; h nmr ( 500 mhz , cdcl3 )  7.64 
 ( d , j = 7.8 hz , 1h ) , 7.52 ( t , j = 
 7.6 hz , 1h ) , 7.39 ( d , j = 7.8 hz , 1h ) , 7.31 ( d , j = 7.6 hz , 1h ) , 4.81 ( m , 1h ) , 4.01 ( m , 1h ) , 3.223.17 
 ( m , 2h ) , 2.802.68 ( m , 5h ) , 1.89 ( m , 2h ) , 1.731.65 
 ( m , 2h ) ; esi ms m / z 330 [ m + h ] ; hplc 96.5% purity ( auc ) , tr = 
 15.6 min ( method c ) .
step a. to 
 a solution of 4-(2-(trifluoromethyl)phenyl)piperidine hydrochloride 
 ( 7 , 0.080 g , 0.30 mmol ) in ch2cl2 was added et3n ( 0.125 ml , 0.90 mmol ) , followed by methyl 
 1-(chlorocarbonyl)pyrrolidine-2-carboxylate ( 0.058 g , 0.30 mmol ) . 
 the mixture stirred at rt for 6 h , was concentrated , and the resulting 
 residue was chromatographed over silica gel ( 05% ch3oh in ch2cl2 ) to give methyl 1-(4-(2-(trifluoromethyl)phenyl)piperidine-1-carbonyl)pyrrolidine-2-carboxylate 
 as a colorless thick oil ( 0.098 g , 84% ) : h nmr ( 300 mhz , 
 cdcl3 )  7.63 ( d , j = 7.8 hz , 1h ) , 
 7.49 ( m , 2h ) , 7.29 ( m , 1h ) , 4.604.55 ( m , 1h ) , 4.023.90 
 ( m , 2h ) , 3.75 ( s , 3h ) , 3.603.44 ( m , 2h ) , 3.122.82 
 ( m , 3h ) , 2.332.23 ( m , 1h ) , 2.091.64 ( m , 7h ) ; esi ms m / z 385
step b. to a solution of methyl 1-(4-(2-(trifluoromethyl)phenyl)piperidine-1-carbonyl)pyrrolidine-2-carboxylate 
 ( 0.098 g , 0.25 mmol ) in ch3oh ( 2 ml ) and thf ( 2 ml ) was 
 added aqueous 2 n naoh ( 2 ml ) .
the mixture stirred at rt for 4 h and 
 was then diluted with h2o and acidified to ph 5with 2 n 
 hcl .
the mixture was extracted with etoac ( 3  30 ml ) , and the 
 organic extracts were dried over na2so4 , filtered , 
 and concentrated under reduced pressure .
the residue was chromatographed 
 over silica gel ( 010% ch3oh in ch2cl2 ) to give 1-(4-(2-(trifluoromethyl)phenyl)piperidine-1-carbonyl)pyrrolidine-2-carboxylic 
 acid ( )-(15 ) as a white solid ( 0.086 g , 91% ) : h nmr ( 300 mhz , cdcl3 )  7.63 ( d , j = 7.8 hz , 1h ) , 7.51 ( t , j = 7.5 hz , 1h ) , 
 7.43 ( d , j = 7.6 hz , 1h ) , 7.30 ( t , j = 7.7 hz , 1h ) , 4.54 ( m , 1h ) , 4.013.94 ( m , 2h ) , 3.51 ( m , 
 2h ) , 3.172.89 ( m , 3h ) , 2.331.66 ( m , 8h ) ; esi ms m / z 327 [ m  co2 + h ] ; hplc 98.1% purity ( auc ) , tr = 
 17.6 min ( method a ) .
step a. a mixture 
 of ( 2-bromoethoxy)-tert - butyldimethylsilane ( 4.6 
 ml , 23.1 mmol ) , 2-trifluoromethylphenol ( 2.50 g , 15.4 mmol ) , ki ( 0.046 
 g , 0.27 mmol ) , and cs2co3 ( 10.0 g , 30.8 mmol ) 
 in dmf ( 69 ml ) was heated at 50 c for 18 h. the mixture was 
 allowed to cool to rt and was diluted with h2o ( 300 ml ) 
 and extracted with etoac ( 4  75 ml ) .
the combined organic extracts 
 were washed with a brine ( 8  50 ml ) and concentrated under reduced 
 pressure to give tert - butyldimethyl(2-(2-(trifluoromethyl)phenoxy)ethoxy)silane 
 as a clear oil ( 4.34 g , 88% ) : h nmr ( 300 mhz , cdcl3 )  7.587.53 ( m , 1h ) , 7.507.41 ( m , 1h ) , 
 7.066.94 ( m , 2h ) , 4.164.10 ( m , 2h ) , 4.013.95 
 ( m , 2h ) , 0.910.87 ( m , 9h ) , 0.100.05 ( m , 6h ) .
step b. to a solution of tert - butyldimethyl(2-(2-(trifluoromethyl)phenoxy)ethoxy)silane 
 ( 4.20 g , 13.1 mmol ) in 1,4-dioxane ( 14 ml ) was added hcl ( 4 m in 1,4-dioxane , 
 14 ml ) .
the obtained oil was diluted with etoac ( 40 ml ) , washed 
 with a saturated brine solution ( 30 ml ) , a 5% licl solution ( 2  
 30 ml ) , and concentrated under reduced pressure .
the resulting residue 
 was chromatographed over silica gel ( isco combiflash rf unit , 80 g 
 redisep column , 050% etoac in hexanes ) to give 2-(2-(trifluoromethyl)phenoxy)ethanol 
 ( 18a ) as an impure white solid ( 1.88 g ) . step c. to a 0 c cooled solution of 2-(2-(trifluoromethyl)phenoxy)ethanol 
 ( 18a , 0.800 g , 3.88 mmol ) in ch2cl2 ( 25 ml ) was added dess 
the mixture was stirred at rt for 18 h , then diluted with ch2cl2 ( 30 ml ) , washed with h2o ( 4  30 ml ) , 
 and concentrated under reduced pressure .
the resulting residue was 
 chromatographed over silica gel ( isco combiflash rf unit , 40 g redisep 
 column , 050% etoac in hexanes ) to give 2-(2-(trifluoromethyl)phenoxy)acetaldehyde 
 a white solid
step d. a solution of 2-(2-(trifluoromethyl)phenoxy)acetaldehyde 
 ( 0.337 g , 1.65 mmol ) in methylamine ( 2 n in ch3oh , 8.3 
 ml , 16.5 mmol ) was stirred at rt for 18 h. the mixture was concentrated 
 to under reduced pressure .
the obtained residue was dissolved in etoh 
 ( 8.3 ml ) and nabh4 ( 0.062 g , 1.65 mmol ) .
the mixture stirred 
 at rt for 2 h and was concentrated under reduced pressure .
the resulting 
 residue was diluted in 2 n naoh ( 40 ml ) and extracted with etoac ( 3 
  30 ml ) .
the obtained residue was chromatographed over 
 silica gel ( isco combiflash rf unit , 12 g redisep column , 010% 
 ch3oh in ch2cl2 with 0.1% nh4oh ) to give n - methyl-2-(2-(trifluoromethyl)phenoxy)ethanamine 
 ( 19a ) as a clear oil ( 0.070 g , 2% for three steps ) : h nmr ( 300 mhz , cdcl3 )  7.597.52 
 ( m , 1h ) , 7.517.42 ( m , 1h ) , 7.056.93 ( m , 2h ) , 4.16 
 ( t , j = 5.1 hz , 2h ) , 3.022.97 ( m , 2h ) , 2.51 
 ( s , 3h ) , missing n  h ; esi ms m / z 220 [ m + h ] .
step e. to a solution 
 of n - methyl-2-(2-(trifluoromethyl)phenoxy)ethanamine 
 ( 19a , 0.058 g , 0.26 mmol ) and et3n ( 0.027 
 g , 0.26 mmol ) in ch2cl2 ( 0.9 ml ) was added methyl 
 2-isocyanatobenzoate ( 0.047 g , 0.26 mmol ) .
the mixture stirred at 
 rt for 2 h and was then diluted with h2o ( 30 ml ) and extracted 
 with ch2cl2 ( 3  30 ml ) .
the resulting residue 
 was chromatographed over silica gel ( isco combiflash rf unit , 12 g 
 redisep column , 050% etoac in hexanes ) to give methyl 2-(3-methyl-3-(2-(2-(trifluoromethyl)phenoxy)ethyl)ureido)benzoate 
 as a white solid ( 84 mg , 79% ) : h nmr ( 300 mhz , dmso - d6 )  10.41 ( s , 1h ) , 8.43 ( dd , j = 8.7 , 0.9 hz , 1h ) , 7.94 ( dd , j = 7.8 , 
 1.5 hz , 1h ) , 7.667.52 ( m , 3h ) , 7.30 ( d , j = 8.7 hz , 1h ) , 7.137.00 ( m , 2h ) , 4.27 ( t , j = 5.4 hz , 2h ) , 3.85 ( s , 3h ) , 3.76 ( t , j = 5.4 hz , 
 2h ) , 3.13 ( s , 3h ) ; esi ms m / z 397 
 [ m + h ] .
step f. to a solution 
 of methyl 2-(3-methyl-3-(2-(2-(trifluoromethyl)phenoxy)ethyl)ureido)benzoate 
 ( 0.084 g , 0.21 mmol ) in thf ( 4.2 ml ) and ch3oh ( 1.9 ml ) 
 was added a solution of liohh2o ( 0.089 g , 2.1 mmol ) 
 in h2o ( 0.98 ml ) . the mixture stirred at rt for 4 h and 

was then acidified to ph 5 with 2 n hcl and diluted with h2o ( 20 ml ) .
the resulting precipitate was collected by filtration 
 to provide 2-(3-(2-(2-(tert - butyl)phenoxy)ethyl)-3-methylureido)benzoic 
 acid ( 20 ) as a white solid ( 0.046 g , 57% ) : mp 171173 
 c ; h nmr ( 500 mhz , dmso - d6 )  13.51 ( br s , 1h ) , 10.89 ( s , 1h ) , 8.46 ( dd , j = 8.5 , 0.5 hz , 1h ) , 7.96 ( dd , j = 8.0 , 1.5 hz , 
 1h ) , 7.647.58 ( m , 2h ) , 7.547.49 ( m , 1h ) , 7.29 ( d , j = 8.5 hz , 1h ) , 7.117.06 ( m , 1h ) , 7.026.97 
 ( m , 1h ) , 4.27 ( t , j = 5.5 hz , 2h ) , 3.75 ( t , j = 5.5 hz , 2h ) , 3.11 ( s , 3h ) ; esi ms m / z 381 [ m  h ] ; hplc 99.0% 
 purity ( auc ) , tr = 10.1 min ( method b ) .
compound 21 was prepared 
 according to a similar procedure described for the synthesis of 20 .
mp 166169 c ; h nmr ( 500 mhz , 
 dmso - d6 )  13.50 ( br s , 1h ) , 10.92 
 ( s , 1h ) , 8.47 ( dd , j = 8.5 , 0.5 hz , 1h ) , 7.95 ( dd , j = 8.0 , 1.5 hz , 1h ) , 7.557.50 ( m , 1h ) , 7.21 ( dd , j = 8.5 , 2.5 hz , 1h ) , 7.31 ( d , j = 2.5 
 hz , 1h ) , 7.066.98 ( m , 2h ) , 4.16 ( t , j = 6.0 
 hz , 2h ) , 3.81 ( t , j = 6.0 hz , 2h ) , 3.10 ( s , 3h ) , 
 1.26 ( s , 9h ) ; esi ms m / z 405 [ m 
 + h ] ; hplc > 99% purity ( auc ) , tr = 12.2 min ( method b ) .
step a. to a 10 
 c cooled suspension of 2-chloroethanamine hydrochloride ( 35.5 
 g , 0.306 mol ) and nahco3 ( 102.8 g , 1.22 mol ) in thf ( 450 
 ml ) and h2o ( 450 ml ) stirring in a 2 l , three - necked , round - bottomed 
 flask equipped with a thermometer was carefully added a solution of 
 di - tert - butyl dicarbonate ( 73.4 g , 0.336 mol ) in 
 thf ( 40 ml ) dropwise over 30 min .
the mixture was allowed to warm 
 to rt and stirred for an additional 24 h. the mixture was diluted 
 with h2o ( 200 ml ) and extracted with etoac ( 3  150 
 ml ) .
the combined organic extracts were washed with h2o 
 ( 100 ml ) , brine ( 100 ml ) , dried over na2so4 , 
 filtered , and concentrated under reduced pressure to give tert - butyl ( 2-chloroethyl)carbamate ( 23 ) as 
 a clear , colorless oil that was used as is in the next step ( 60.96 
 g , quantitative% ) : h nmr ( 500 mhz , cdcl3 )  
 4.89 ( bs , 1h ) , 3.60 ( m , 2h ) , 3.46 ( m , 2h ) , 1.45 ( s , 9h ) .
step b. a 2 l , three - necked , round - bottomed flask equipped 
 with a thermometer , reflux condenser , and mechanical stirrer were 
 charged with tert - butyl ( 2-chloroethyl)carbamate 
 ( 23 , 65.28 g , 337 mmol ) , 2-(tert - butyl)phenol 
 ( 34.0 ml , 222 mmol ) , ki ( 0.365 g , 2.20 mmol ) , cs2co3 ( 183 g , 560 mmol ) , and dmf ( 700 ml ) , and the mixture was 
 heated at 60 c for 16 h. the mixture was allowed to cool to 
 rt and was diluted with h2o ( 1 l ) and extracted with etoac 
 ( 3  200 ml ) .
the combined organic extracts were washed with 
 5% aqueous licl solution ( 3  250 ml ) , brine ( 250 ml ) , dried 
 over na2so4 , filtered , and concentrated under 
 reduced pressure .
the residue was purified over a plug of silica gel 
 ( 015% etoac in hexanes ) to give tert - butyl 
 ( 2-(2-(tert - butyl)phenoxy)ethyl)carbamate 
 ( 24 ) as a yellow solid ( 53.46 g , 82% ) : h 
 nmr ( 500 mhz , cdcl3 )  7.28 ( m , 1h ) , 7.16 ( m , 1h ) , 
 6.92 ( m , 1h ) , 6.83 ( m , 1h ) , 4.83 ( bs , 1h ) , 4.07 ( m , 2h ) , 3.59 ( m , 
 2h ) , 1.39 ( s , 9h ) .
step c. to a 0 c cooled 
 solution of lialh4 in thf ( 1.0 m , 367 ml , 360 mmol ) in 
 thf ( 350 ml ) in a 3 l , 
 three - necked , round - bottomed flask equipped with a thermometer was 
 carefully added a solution of tert - butyl ( 2-(2-(tert - butyl)phenoxy)ethyl)carbamate ( 24 , 43.06 g , 147 mmol ) in thf ( 100 ml ) . upon complete addition
, the 
 mixture was allowed to warm to rt followed by heating at 60 c 
 for 16 h. the mixture was allowed to cool back to rt and then further 
 cooled to 0 c .
the mixture was carefully quenched by slow addition 
 of h2o ( 15 ml ) , 15% aqueous naoh solution ( 15 ml ) , followed 
 by additional h2o ( 40 ml ) .
the rate of quenching was done 
 carefully so as to maintain an internal temperature below 25 c . 

the aqueous 
 filtrate was extracted with et2o ( 2  150 ml ) , and 
 the organic extracts were combined , dried over na2so4 , filtered , and concentrated under reduced pressure .
the residue 
 was purified by flash column chromatography ( isco combiflash rf unit , 
 two 330 g redisep columns , 050% ch3oh in ch2cl2 ) to give 2-(2-(tert - butyl)phenoxy)-n - methylethanamine as an oil ( 13.4 g ) .
this material was 
 dissolved in et2o ( 250 ml ) and treated with a solution 
 of 2 m hcl in et2o ( 85 ml ) at 0 c .
the mixture stirred 
 for 10 min at rt and was concentrated under reduced pressure to give 
 2-(2-(tert - butyl)phenoxy)-n - methylethanamine 
 hydrochloride as a white solid ( 15.3 g , 43% ) : h nmr ( 500 
 mhz , dmso - d6 )  9.14 ( bs , 1h ) , 7.25 
 ( m , 1h ) , 7.18 ( m , 1h ) , 7.04 ( m , 1h ) , 6.94 ( m , 1h ) , 4.29 ( m , 2h ) , 3.36 
 ( m , 2h ) , 2.65 ( s , 3h ) , 1.34 ( s , 9h ) . step d. to a solution of 2-(2-(tert - butyl)phenoxy)-n - methylethanamine hydrochloride 
 ( 0.066 g , 0.312 mmol ) and et3n ( 0.038 g , 0.381 mmol ) in 
 ch2cl2 ( 3.0 ml ) was added methyl 2-isocyanatobenzoate 
 ( 0.062 g , 0.352 mmol ) , and the mixture was stirred at rt for 18 h. 
 the mixture was diluted with h2o ( 30 ml ) , extracted with 
 ch2cl2 ( 3  30 ml ) , and the combined organic 
 extracts were concentrated under reduced pressure .
the resulting residue 
 was chromatographed over silica gel ( 05% ch3oh 
 in ch2cl2 with 0.01% nh4oh ) to give 
 methyl 2-(3-(2-(2-(tert - butyl)phenoxy)ethyl)-3-methylureido)benzoate 
 as a white solid ( 0.057 mg , 46% ) : h nmr ( 300 mhz , cdcl3 )  10.74 ( s , 1h ) , 8.60 ( dd , j = 9.0 , 
 1.2 hz , 1h ) , 8.00 ( dd , j = 8.1 , 1.8 hz , 1h ) , 7.557.47 
 ( m , 1h ) , 7.307.26 ( m , 1h ) , 7.207.12 ( m , 1h ) , 7.026.94 
 ( m , 1h ) , 6.936.86 ( m , 2h ) , 4.23 ( t , j = 5.4 
 hz , 2h ) , 3.933.87 ( m , 5h ) , 3.27 ( s , 3h ) , 1.38 ( s , 9h ) ; esi 
 ms m / z 385 [ m + h ] . step e. to a solution of methyl 2-(3-(2-(2-(tert - butyl)phenoxy)ethyl)-3-methylureido)benzoate 
 ( 0.054 g , 0.142 mmol ) in thf ( 2.7 ml ) and ch3oh ( 1.3 ml ) 
 was added a solution of liohh2o ( 0.059 g , 1.41 mmol ) 
 in h2o ( 0.66 ml ) , and the mixture stirred at rt for 18 
 h. the mixture was acidified to ph 5with 2 n hcl , diluted with h2o ( 10 ml ) , and extracted with et2o ( 4  20 
 ml ) .
the combined organic extracts were dried over na2so4 , filtered , and concentrated to provide 2-(3-(2-(2-(tert - butyl)phenoxy)ethyl)-3-methylureido)benzoic 
 acid ( 25 ) as a white solid ( 0.037 mg , 97% ) : mp 136141 
 c ; h nmr ( 500 mhz , dmso - d6 )  13.50 ( s , 1h ) , 10.93 ( s , 1h ) , 8.48 ( dd , j = 8.5 , 0.5 hz , 1h ) , 7.95 ( dd , j = 8.0 , 1.5 hz , 
 1h ) , 7.567.50 ( m , 1h ) , 7.217.13 ( m , 2h ) , 7.026.97 
 ( m , 2h ) , 6.886.83 ( m , 1h ) , 4.15 ( t , j = 6.00 
 hz , 2h ) , 3.82 ( t , j = 6.0 hz , 2h ) , 3.11 ( s , 3h ) , 
 1.28 ( s , 9h ) ; esi ms m / z 371 [ m 
 + h ] ; hplc 98.4% purity ( auc ) , tr = 14.3 min ( method b ) .
step a. to a solution 
 of tert - butyl ( 2-chloroethyl)carbamate ( 23 , 2.61 g , 14.5 mmol ) in thf ( 40 ml ) was added ch3i ( 9.0 
 ml , 145 mmol ) at rt , followed by dropwise addition of a solution of 
 lihmds ( 1.0 m in thf , 18.9 ml , 18.9 mmol ) over 10 min .
the reaction 
 mixture stirred at rt for an additional 20 min and was then diluted 
 with h2o ( 75 ml ) and extracted with et2o ( 4 
  100 ml ) .
the combined organics were washed with a saturated 
 brine solution ( 2  30 ml ) , dried over na2so4 , filtered , and concentrated under reduced pressure to provide tert - butyl ( 2-chloroethyl)(methyl)carbamate as a yellow 
 oil ( 2.61 g , 92% ) : h nmr ( 300 mhz , cdcl3 )  
 3.683.45 ( m , 4h ) , 2.93 ( s , 3h ) , 1.46 ( s , 9h ) . step b. a mixture of tert - butyl ( 2-chloroethyl)(methyl)carbamate 
 ( 1.72 g , 8.92 mmol ) , 2-(tert - butyl)-4-fluorophenol 
 ( 1.00 g , 5.94 mmol ) , ki ( 18 mg , 0.10 mmol ) , and cs2co3 ( 4.93 g , 15.1 mmol ) in dmf ( 23 ml ) was heated at 60 c 
 for 100 h. the mixture was allowed to cool to rt and was diluted with 
 h2o ( 100 ml ) and extracted with etoac ( 4  80 ml ) . 

the combined organic extracts were washed with a saturated brine solution 
 ( 2  50 ml ) and concentrated under reduced pressure .
the resulting 
 residue was chromatographed over silica gel ( isco combiflash rf unit , 
 40 g redisep column , 010% etoac in hexanes ) to give tert - butyl ( 2-(2-(tert - butyl)-4-fluorophenoxy)ethyl)(methyl)carbamate 
 ( 26 ) as an orange oil ( 0.490 g , 25% ) : h nmr 
 ( 300 mhz , cdcl3 )  7.036.95 ( m , 1h ) , 6.886.73 
 ( m , 2h ) , 4.07 ( t , j = 5.7 hz , 2h ) , 3.66 ( t , j = 5.7 hz , 2h ) , 2.97 ( s , 3h ) , 1.46 , ( s , 9h ) , 1.36 ( s , 9h ) .
step c. to a solution of tert - butyl ( 2-(2-(tert - butyl)-4-fluorophenoxy)ethyl)(methyl)carbamate 
 ( 26 , 0.490 g , 1.51 mmol ) in ch2cl2 ( 6.0 ml ) was added hcl ( 2 n solution in et2o , 6.0 ml ) , 
 and the mixture stirred at rt for 6 h. the mixture was then diluted 
 with et2o ( 30 ml ) , and the resulting solids were collected 
 by filtration to give 2-(2-(tert - butyl)-4-fluorophenoxy)-n - methylethanamine hydrochloride as a white solid ( 0.185 
 g , 46% ) : h nmr ( 300 mhz , dmso - d6 )  8.84 ( br s , 2h ) , 7.086.98 ( m , 3h ) , 4.24 ( t , j = 5.7 hz , 2h ) , 3.433.28 ( m , 2h , overlaps with 
 h2o ) , 2.67 ( s , 3h ) , 1.33 ( s , 9h ) ; esi ms m / z 226 [ m + h ] .
step d. to a solution of 2-(2-(tert - butyl)-4-fluorophenoxy)-n - methylethanamine hydrochloride 
 ( 0.085 g , 0.32 mmol ) and et3n ( 0.066 g , 0.65 mmol ) in ch2cl2 ( 1.1 ml ) was added methyl 2-isocyanatobenzoate 
 ( 0.064 g , 0.326 mmol ) .
the mixture was stirred at rt for 3 h , was 
 then diluted with h2o ( 10 ml ) , and was extracted with ch2cl2 ( 4  10 ml ) .
the resulting residue was 
 chromatographed over silica gel ( isco combiflash rf unit , 12 g redisep 
 column , 020% etoac in hexanes ) to give methyl 2-(3-(2-(2-(tert - butyl)-4-fluorophenoxy)ethyl)-3-methylureido)benzoate 
 as a white solid ( 0.116 g , 88% ) : h nmr ( 300 mhz , cdcl3 )  10.74 ( s , 1h ) , 8.60 ( d , j = 8.7 
 hz , 1h ) , 8.00 ( dd , j = 8.1 , 1.5 hz , 1h ) , 7.557.48 
 ( m , 1h ) , 7.016.94 ( m , 2h ) , 6.836.78 ( m , 2h ) , 4.18 
 ( t , j = 5.7 hz , 2h ) , 3.913.84 ( m , 5h ) , 3.26 
 ( s , 3h ) , 1.36 ( s , 9h ) ; esi ms m / z 403 [ m + h ] .
step e. to a solution 
 of methyl 2-(3-(2-(2-(tert - butyl)-4-fluorophenoxy)ethyl)-3-methylureido)benzoate 
 ( 0.110 g , 0.27 mmol ) in thf ( 5.4 ml ) and ch3oh ( 2.8 ml ) 
 was added a solution of liohh2o ( 0.114 g , 2.73 mmol ) 
 in h2o ( 1.4 ml ) .
the mixture stirred at rt for 18 h , was 
 then acidified to ph 5 with 2 n hcl , and was diluted with h2o ( 30 ml ) .
the resulting solids were collected by filtration and 
 washed with h2o to provide 2-(3-(2-(2-(tert - butyl)-4-fluorophenoxy)ethyl)-3-methylureido)benzoic acid ( 27 ) as a white solid ( 0.099 g , 93% ) : mp 145150 c ; h nmr ( 500 mhz , dmso - d6 )  
 13.51 ( s , 1h ) , 10.94 ( s , 1h ) , 8.47 ( d , j = 8.5 hz , 
 1h ) , 7.95 ( dd , j = 8.0 , 1.5 hz , 1h ) , 7.557.49 
 ( m , 1h ) , 7.036.93 ( m , 4h ) , 4.14 ( t , j = 5.5 
 hz , 2h ) , 3.80 ( t , j = 6.0 hz , 2h ) , 3.10 ( s , 3h ) , 
 1.26 ( s , 9h ) ; esi ms m / z 389 [ m 
 + h ] ; hplc > 99% purity ( auc ) , tr = 11.6 min ( method b ) .
step a. to a solution 
 of 2,3,4,5-tetrahydro-1h - benzo[d]azepine ( 0.110 g , 0.74 mmol ) 
 and et3n ( 0.12 ml , 0.82 mmol ) in ch2cl2 ( 2.4 ml ) was added methyl 2-isocyanatobenzoate ( 0.132 mg , 0.74 mmol ) , 
 and the mixture stirred at rt for 2 h. the mixture was diluted with 
 h2o ( 20 ml ) and extracted with ch2cl2 ( 3  30 ml ) .
the combined organic extracts were concentrated 
 under reduced pressure , and the resulting residue was chromatographed 
 over silica gel ( isco combiflash rf unit , 12 g redisep column , 025% 
 etoac in hexanes ) to give methyl 2-(2,3,4,5-tetrahydro-1h - benzo[d]azepine-3-carboxamido)benzoate as a clear 
 film ( 0.203 g , 83% ) : h nmr ( 500 mhz , dmso - d6 )  10.46 ( br s , 1h ) , 8.34 ( d , j = 8.0 hz , 1h ) , 7.94 ( dd , j = 8.0 , 1.5 hz , 1h ) , 
 7.587.53 ( m , 1h ) , 7.207.16 ( m , 2h ) , 7.157.10 
 ( m , 2h ) , 7.067.02 ( m , 1h ) , 3.89 ( s , 3h ) , 3.683.61 
 ( m , 4h ) , 3.012.94 ( m , 4h ) ; esi ms m / z 325 [ m + h ] . step b. to a solution of methyl 2-(2,3,4,5-tetrahydro-1h - benzo[d]azepine-3-carboxamido)benzoate ( 0.197 g , 
 0.60 mmol ) in thf ( 12.0 ml ) and ch3oh ( 5.6 ml ) was added 
 a solution of liohh2o ( 0.255 g , 6.07 mmol ) in h2o ( 2.8 ml ) . the mixture stirred at rt for 3 h , was neutralized 
 with 2 n hcl , and was diluted with h2o ( 30 ml ) .
the resulting 
 precipitate was collected by filtration to give 2-(2,3,4,5-tetrahydro-1h - benzo[d]azepine-3-carboxamido)benzoic 
 acid ( 28 ) as a white solid ( 0.065 mg , 34% ) : mp 272278 
 c ; h nmr ( 500 mhz , dmso - d6 )  14.18 ( br s , 1h ) , 8.30 ( d , j = 8.5 hz , 
 1h ) , 7.92 ( d , j = 7.5 hz , 1h ) , 7.197.08 ( m , 
 5h ) , 6.796.74 ( m , 1h ) , 3.653.60 ( m , 4h ) , 2.942.88 
 ( m , 4h ) missing urea n 
h ; esi ms m / z 309 [ m  h ] ; hplc > 99% purity 
 ( auc ) , tr = 14.8 min ( method a ) .
step a. a mixture 
 of 2-(trifluoromethyl)benzaldehyde ( 5.0 g , 28.7 mmol ) and hydrazine 
 hydrate ( 1.43 g , 28.7 mmol ) in i - proh ( 100 ml ) was 
 heated at reflux for 1 h. the mixture cooled to rt and was concentrated 
 under reduced pressure providing ( e)-(2-(trifluoromethyl)benzylidene)hydrazine , 
 which was a yellow oil that crystallized upon standing ( 5.1 g , 94% ) . 

step b. to a solution of ( e)-(2-(trifluoromethyl)benzylidene)hydrazine 
 ( 5.0 g , 26.5 mmol ) in 1,4-dioxane ( 200 ml ) was added mno2 ( 23.1 g , 256 mmol ) portionwise , and the mixture stirred at rt for 
 3 h. the slurry was filtered through celite and rinsed with additional 
 1,4-dioxane ( 50 ml ) . to the filtrate was added 1-benzyl-1h - pyrrole-2,5-dione ( 4.92 g , 26.5 mmol ) , and the mixture was stirred 
 at rt for 48 h. the mixture was concentrated under reduced pressure 
 and the resulting residue was chromatographed over silica gel ( isco 
 combiflash rf unit , 330 g redisep column , 05% etoac in hexanes ) 
 to give ( 1r,5s,6s)-3-benzyl-6-(2-(trifluoromethyl)phenyl)-3-azabicyclo[3.1.0]hexane-2,4-dione 
 ( 1.52 g , 17% ) as a white solid : h nmr ( 500 mhz , cdcl3 )  7.69 ( d , j = 7.8 hz , 1h ) , 7.52 
 ( m , 1h ) , 7.49 ( m , 1h ) , 7.407.29 ( m , 5h ) , 7.10 ( d , j = 7.8 hz , 1h ) , 4.58 ( s , 2h ) 2.90 ( m , 1h ) , 2.82 ( m , 2h ) ; 
 esi ms m / z 346 [ m + h ] .
step c. to a solution of ( 1r,5s,6s)-3-benzyl-6-(2-(trifluoromethyl)phenyl)-3-azabicyclo[3.1.0]hexane-2,4-dione 
 ( 1.24 g , 3.59 mmol ) in thf ( 20 ml ) was added nabh4 ( 0.339 
 g , 8.97 mmol ) , and the mixture stirred at rt for 15 min . to this was 
 added bf3et2o ( 1.0 m solution in thf , 
 5.38 ml , 5.38 mmol ) dropwise ( gas evolution was observed ) .
the mixture 
 was then heated at 50 c for 5 h. the mixture was allowed to 
 cool back to rt and was carefully quenched by dropwise addition of 
 h2o ( added until gas evolution no longer occurred ) . to 
 this was added ch3oh ( 60 ml ) , and the resulting mixture 
 was stirred at reflux for 16 h. the mixture cooled back to rt and 
 was concentrated under reduced pressure .
the resulting residue was 
 taken up in h2o ( 50 ml ) and extracted with etoac ( 3  
 50 ml ) .
the combined organic extracts were concentrated under reduced 
 pressure , and the resulting residue was chromatographed over silica 
 gel ( isco combiflash rf unit , 12 g redisep column , 025% etoac 
 in hexanes ) to give ( 1r,5s,6s)-3-benzyl-6-(2-(trifluoromethyl)phenyl)-3-azabicyclo[3.1.0]hexane 
 as a colorless , viscous oil ( 0.720 g , 64% ) : h nmr ( 500 
 mhz , cdcl3 )  7.64 ( d , j = 7.8 hz , 
 1h ) , 7.45 ( m , 1h ) , 7.357.35 ( m , 4h ) , 7.297.21 ( m , 
 2h ) , 7.08 ( d , j = 7.8 hz , 1h ) , 3.67 ( s , 2h ) , 3.14 
 ( d , j = 7.8 hz , 2h ) , 2.71 ( m , 1h ) , 2.49 ( m , 2h ) , 
 1.74 ( m , 2h ) . step d. a mixture of ( 1r,5s,6s)-3-benzyl-6-(2-(trifluoromethyl)phenyl)-3-azabicyclo[3.1.0]hexane 
 ( 0.700 g , 2.20 mmol ) and 10% pd / c ( 0.200 g ) in ch3oh ( 50 
 ml ) was subjected to a 50 psi atmosphere of h2 at rt for 
 4 h using a parr shaker apparatus . the mixture was filtered through 
 celite and the filtrate was concentrated under reduced pressure to 
 give ( 1r,5s,6s)-6-(2-(trifluoromethyl)phenyl)-3-azabicyclo[3.1.0]hexane 
 as a viscous oil ( 0.478 g , 95% ) : h nmr ( 500 mhz , cdcl3 )  7.61 ( d , j = 7.8 hz , 1h ) , 7.46 
 ( m , 1h ) , 7.24 ( m , 1h ) , 7.10 ( d , j = 7.8 hz , 1h ) , 
 3.17 ( d , j = 7.8 hz , 2h ) , 3.02 ( m , 2h ) , 1.93 ( m , 
 1h ) , 1.74 ( m , 2h ) , 1.68 ( bs , 1h ) .
step e. to 
 a solution of ( 1r,5s,6s)-6-(2-(trifluoromethyl)phenyl)-3-azabicyclo[3.1.0]hexane 
 ( 0.100 g , 0.44 mmol ) in ch2cl2 ( 10 ml ) was added 
 methyl 2-isocyanatobenzoate ( 0.078 g , 0.44 mmol ) , and the mixture 
 stirred at rt for 2 h. the mixture was diluted with h2o 
 ( 20 ml ) and extracted with ch2cl2 ( 3  
 30 ml ) .
the combined organic extracts were concentrated under reduced 
 pressure , and the resulting residue was chromatographed over silica 
 gel ( isco combiflash rf unit , 12 g redisep column , 025% etoac 
 in hexanes ) to give methyl 2-((1r,5s,6s)-6-(2-(trifluoromethyl)phenyl)-3-azabicyclo[3.1.0]hexane-3-carboxamido)benzoate 
 as a white solid ( 0.110 g , 62% ) : h nmr ( 500 mhz , cdcl3 )  10 .. 55 ( bs , 1h ) , 8.62 ( m , 1h ) , 8.07 ( m , 1h ) , 7.65 
 ( m , 1h ) , 7.557.43 ( m , 2h ) , 7.25 ( m , 1h ) , 7.11 ( m , 1h ) , 6.95 
 ( m , 1h ) , 3.97 ( m , 5h ) , 3.72 ( m , 2h ) , 2.19 ( m , 1h ) , 2.09 ( m , 2h ) ; esi 
 ms m / z 403 [ m  h ] . step f. to a solution of methyl 2-((1r,5s,6s)-6-(2-(trifluoromethyl)phenyl)-3-azabicyclo[3.1.0]hexane-3-carboxamido)benzoate 
 ( 0.110 g , 0.27 mmol ) in thf ( 2 ml ) and ch3oh ( 4 ml ) was 
 added 2 n naoh ( 2 ml ) .
the mixture was stirred at rt for 3 h and was 
 then acidified to ph 5 with 2 n hcl .
the resulting precipitate was 
 collected by filtration to 2-((1r,5s,6s)-6-(2-(trifluoromethyl)phenyl)-3-azabicyclo[3.1.0]hexane-3-carboxamido)benzoic 
 acid ( 29 ) as a white solid ( 0.105 g , 98% ) : mp 205208 
 c ; h nmr ( 500 mhz , dmso - d6 )  13.52 ( bs , 1h ) , 10.74 ( bs , 1h ) , 8.49 ( m , 1h ) , 7.97 ( m , 
 1h ) , 7.70 ( m , 1h ) , 7.61 ( m , 1h ) , 7.55 ( m , 1h ) , 7.42 ( m , 1 ) , 7.31 ( m , 
 1h ) , 6.99 ( m , 1h ) , 3.74 ( m , 2h ) , 3.65 ( m , 2h ) , 2.19 ( m , 2h ) , 1.92 
 ( m , 1h ) ; esi ms m / z 389 [ m  
 h ] ; hplc 97.3% purity ( auc ) , tr = 20.4 min ( method a ) .
compound 30 was prepared 
 according to a similar procedure described for the synthesis of 29 .
mp 162165 c ; h nmr ( 500 mhz , 
 dmso - d6 )  8.06 ( m , 1h ) , 7.87 ( m , 
 1h ) , 7.65 ( m , 1h ) , 7.49 ( m , 2h ) , 7.32 ( m , 2h ) , 6.85 ( m , 1h ) , 3.70 
 ( m , 1h ) , 3.50 ( m , 2h ) , 2.31 ( m , 1h ) , 2.11 ( m , 2h ) , n 
h missing ; 
 esi ms m / z 389 [ m  h ] ; hplc > 99% purity ( auc ) , tr = 13.2 min ( method a ) .
step a. a mixture 
 of tert - butyl 2,6-diazaspiro[3.3]heptane-2-carboxylate 
 hemioxalate ( 0.200 g , 1.01 mmol ) , 1-bromo-(2-trifluoromethyl)benzene 
 ( 0.14 ml , 1.03 mmol ) , pd(dba)3 ( 0.014 g , 0.015 mmol ) , rac - binap(0.140 g , 0.225 mmol ) , and k2co3 ( 0.340 g , 3.03 mmol ) in toluene ( 5 ml ) was heated at 110 
 c in a sealed tube for 24 h. the mixture cooled to rt and was 
 diluted with etoac ( 10 ml ) , filtered through celite , and the filtrate 
 was concentrated under reduced pressure .
the residue was chromatographed 
 over silica gel ( isco combiflash rf unit , 40 g redisep column , 0100% 
 etoac in hexanes ) to provide tert - butyl 6-(2-(trifluoromethyl)phenyl)-2,6-diazaspiro[3.3]heptane-2-carboxylate 
 as a tan solid ( 0.131 g , 38% ) : h nmr ( 500 mhz , cdcl3 )  7.507.48 ( m , 1h ) , 7.377.37 ( m , 1h ) , 
 6.816.78 ( m , 1h ) , 6.48 ( d , j = 8.5 hz , 1h ) , 
 4.054.10 ( m , 8h ) , 1.44 ( s , 9h ) . step b. to a solution of tert - butyl 6-(2-(trifluoromethyl)phenyl)-2,6-diazaspiro[3.3]heptane-2-carboxylate 
 ( 0.131 g , 0.38 mmol ) in ch2cl2(2 ml ) was added 
 2 m hcl in et2o ( 2 ml ) , and the mixture stirred at rt for 
 4 h. the mixture was concentrated under reduced pressure , and the 
 resulting residue was dissolved in ch2cl2 ( 4 
 ml ) . to this solution
were added et3n ( 0.12 ml , 0.86 mmol ) 
 and methyl-2-isocyanatobenzoate ( 80 mg , 0.45 mmol ) , and the mixture 
 stirred at rt for 24 h. the mixture was washed with saturated aqueous 
 2 m nahco3 solution ( 10 ml ) and extracted with ch2cl2 ( 2  10 ml ) .
the combined organic extracts were 
 dried over na2so4 , filtered , and concentrated 
 under reduced pressure .
the resulting residue was chromatographed 
 over silica gel ( isco combiflash rf unit , 24 g redisep column , 050% 
 etoac in hexanes ) to provide methyl 2-(6-(2-(trifluoromethyl)phenyl)-2,6-diazaspiro[3.3]heptanes-2-carboxamido)benzoate 
 as an off - white solid ( 0.080 g , 50% ) : h nmr ( 500 mhz , 
 cdcl3 )  8.52 ( d , j = 8.5 hz , 1h ) , 
 7.997.98 ( m , 1h ) , 7.537.44 ( m , 2h ) , 7.367.33 
 ( m , 1h ) , 6.996.96 ( m , 2h ) , 6.71 ( t , j = 7.5 
 hz , 1h ) , 4.86 ( br s , 1h ) , 3.92 ( s , 3h ) , 3.68 ( d , j = 11.35 hz , 2h ) , 3.55 ( d , j = 11.35 hz , 2h ) , 3.473.46 
 ( m , 2h ) , 3.353.34 ( m , 2h ) .
step c. to 
 a mixture of methyl 2-(6-(2-(trifluoromethyl)phenyl)-2,6-diazaspiro[3.3]heptanes-2-carboxamido)benzoate 
 ( 0.080 g , 0.19 mmol ) in ch3oh ( 3 ml ) and thf ( 3 ml ) was 
 added liohh2o ( 0.080 g , 1.91 mmol ) in h2o ( 10 ml ) .
the mixture was stirred at rt for 3 h followed by acidification 
 to ph 6 with 2 n hcl .
the mixture was further diluted with h2o ( 10 ml ) , and the resulting precipitate was collected by filtration . 

the material was recrystallized from etoac and heptanes to provide 
 ( 31 ) 2-(6-(2-(trifluoromethyl)phenyl)-2,6-diazaspiro[3.3]heptanes-2-carboxamido)benzoic 
 acid as a white solid ( 0.049 mg , 64% ) : mp 181184 c ; h nmr ( 500 mhz , dmso - d6 )  
 11.66 ( s , 1h ) , 7.96 ( m , 1h ) , 7.697.66 ( m , 1h ) , 7.457.42 
 ( m , 2h ) , 7.247.18 ( m , 2h ) , 6.926.90 ( m , 1h ) , 6.72 
 ( t , j = 7.5 hz , 1h ) , 6.076.05 ( m , 1h ) , 4.314.21 
 ( m , 2h ) , 3.863.79 ( m , 4h ) , 3.483.45 ( m , 2h ) ; esi ms m / z 404 [ m  h ] ; hplc 96.4% purity ( auc ) , tr = 14.7 
 min ( method a ) .
compound 32 was prepared 
 according to a similar procedure described for the synthesis of 28 .
mp 192195 c ; h nmr ( 500 mhz , 
 dmso - d6 )  13.52 ( br s , 1h ) , 10.59 
 ( s , 1h ) , 8.46 ( d , j = 8.5 hz , 1h ) , 7.977.91 
 ( m , 2h ) , 7.787.71 ( m , 2h ) , 7.577.48 ( m , 2h ) , 7.046.98 
 ( m , 1h ) , 4.474.37 ( m , 2h ) , 4.254.17 ( m , 1h ) , 4.154.02 
 ( m , 2h ) ; esi ms m / z 363 [ m  
 h ] ; hplc > 99% purity ( auc ) , tr = 13.8 min ( method b ) .
step a. to a 0 c 
 cooled solution of azetidin-3-ol hydrochloride ( 2.00 g , 18.21 mmol ) 
 and et3n ( 3.65 ml , 26.01 mmol ) in ch3oh ( 18 
 ml ) was added di - tert - butyl dicarbonate ( 2.82 g , 
 12.9 mmol ) . the resulting mixture stirred at rt for 18 h. the mixture 
 diluted with ch2cl2 ( 100 ml ) and washed with 
 h2o ( 3  30 ml ) .
the organic layer was dried over 
 na2so4 , filtered , and concentrated under reduced 
 pressure to give tert - butyl 3-hydroxyazetidine-1-carboxylate 
 as a white solid ( 1.74 g , 78% ) : h nmr ( 500 mhz , dmso - d6 ) 5.625.58 ( m , 1h ) , 4.394.32 
 ( m , 1h ) , 4.013.93 ( m , 2h ) , 3.603.51 ( m , 2h ) , 1.36 
 ( m , 9h ) .
step b. to a 0 c cooled solution 
 of tert - butyl 3-hydroxyazetidine-1-carboxylate ( 1.73 
 g , 9.99 mmol ) and et3n ( 1.69 ml , 12.01 mmol ) in ch2cl2 ( 51 ml ) was added mscl ( 0.85 ml , 11.0 mmol ) . 

the mixture continued to stir at 0 c for 1 h. the mixture was 
 diluted with a saturated brine solution ( 70 ml ) and extracted with 
 ch2cl2 ( 3  40 ml ) .
the combined organic 
 extracts were dried over na2so4 , filtered , and 
 concentrated under reduced pressure to give to give tert - butyl 3-((methylsulfonyl)oxy)azetidine-1-carboxylate 
 as a light yellow oil ( 2.60 g , > 99% ) : h nmr ( 500 mhz , 
 cdcl3 )  5.225.16 ( m , 1h ) , 4.294.24 
 ( m , 2h ) , 4.124.07 ( m , 2h ) , 3.06 ( s , 3h ) , 1.44 ( s , 9h ) .
step c. a mixture of tert - butyl 
 3-((methylsulfonyl)oxy)azetidine-1-carboxylate ( 2.51 g , 9.99 mmol ) , 
 2-trifluoromethylphenol ( 1.62 g , 9.99 mmol ) , cs2co3 ( 3.57 g , 11.0 mmol ) in dmf ( 90 ml ) was heated at 80 c 
 for 18 h. the mixture was allowed to cool to rt and was diluted with 
 a saturated brine solution ( 50 ml ) and extracted with etoac ( 3  
 50 ml ) .
the combined organic extracts were washed with a saturated 
 brine solution ( 2  50 ml ) and concentrated under reduced pressure . 

the resulting residue was chromatographed over silica gel ( isco combiflash 
 rf unit , 40 g redisep column , 060% etoac in hexanes ) to give tert - butyl 3-(2-(trifluoromethyl)phenoxy)azetidine-1-carboxylate 
 as a clear oil ( 1.49 mg , 47% ) : h nmr ( 500 mhz , cdcl3 )  7.60 ( d , j = 7.5 hz , 1h ) , 7.607.43 
 ( m , 1h ) , 7.087.04 ( m , 1h ) , 6.63 ( d , j = 8.0 
 hz , 1h ) , 4.984.92 ( m , 1h ) , 4.344.29 ( m , 2h ) , 4.084.04 
 ( m , 2h ) , 1.45 ( s , 9h ) ; esi ms m / z 262 [ m  t - bu ] .
step d. to a solution of tert - butyl 3-(2-(trifluoromethyl)phenoxy)azetidine-1-carboxylate 
 ( 0.255 g , 0.80 mmol ) in ch3oh ( 1.5 ml ) was added 2 m hcl 
 in et2o ( 1.5 ml ) , and the mixture was stirred at rt for 
 2 h. the mixture was diluted with et2o ( 30 ml ) and the 
 resulting precipitate was collected by filtration to give 3-(2-(trifluoromethyl)phenoxy)azetidine 
 as a white solid ( 0.182 g , 89% ) : h nmr ( 500 mhz , dmso - d6 )  9.45 ( s , 2h ) , 7.68 ( d , j = 7.5 hz , 1h ) , 7.657.60 ( m , 1h ) , 7.207.17 ( m , 1h ) , 
 7.04 ( d , j = 8.5 hz , 1h ) , 5.255.20 ( m , 1h ) , 
 4.504.45 ( m , 2h ) , 4.013.97 ( m , 2h ) ; esi ms m / z 218 [ m + h ] .
step e. to a mixture of 3-(2-(trifluoromethyl)phenoxy)azetidine 
 hydrochloride ( 0.080 g , 0.31 mmol ) and et3n ( 88 l , 
 0.63 mmol ) in ch2cl2 ( 1.0 ml ) was added methyl 
 2-isocyanatobenzoate ( 0.056 g , 0.31 mmol ) .
the mixture stirred at 
 rt for 18 h followed by dilution with h2o ( 5 ml ) .
the mixture 
 was extracted with ch2cl2 ( 3  10 ml ) , 
 and the combined organic extracts were washed with a saturated brine 
 solution ( 1  10 ml ) and concentrated under reduced pressure . 

the resulting residue was chromatographed over silica gel ( isco combiflash 
 rf unit , 12 g redisep column , 050% etoac in hexanes ) to give 
 methyl 2-(3-(2-(trifluoromethyl)phenoxy)azetidine-1-carboxamido)benzoate 
 as a white solid ( 92 mg , 74% ) : h nmr ( 500 mhz , dmso - d6 )  10.04 ( s , 1h ) , 8.35 ( d , j = 8.5 hz , 1h ) , 7.93 ( dd , j = 8.0 , 1.5 hz , 1h ) , 
 7.697.64 ( m , 2h ) , 7.597.55 ( m , 1h ) , 7.197.16 
 ( m , 1h ) , 7.107.04 ( m , 2h ) , 5.275.24 ( m , 1h ) , 4.584.50 
 ( m , 2h ) , 3.993.93 ( m , 2h ) , 3.86 ( s , 3h ) ; esi ms m / z 395 [ m + h ] .
step f. to a mixture of methyl 2-(3-(2-(trifluoromethyl)phenoxy)azetidine-1-carboxamido)benzoate 
 ( 0.090 g , 0.22 mmol ) in thf ( 4.5 ml ) and ch3oh ( 2.1 ml ) 
 was added a solution of liohh2o ( 0.095 g , 2.28 mmol ) 
 in h2o ( 1.1 ml ) .
the mixture stirred at rt for 18 h , followed 
 by neutralization with 2 n hcl , and diluted with additional h2o ( 30 ml ) .
the resulting precipitate was collected by filtration 
 to provide 2-(3-(2-(trifluoromethyl)phenoxy)azetidine-1-carboxamido)benzoic 
 acid ( 33 ) as a white solid ( 0.074 g , 85% ) : mp 186189 
 c ; h nmr ( 500 mhz , dmso - d6 )  13.53 ( br s , 1h ) , 10.58 ( s , 1h ) , 8.41 ( d , j = 8.5 hz , 1h ) , 7.95 ( dd , j = 8.0 , 1.0 hz , 1h ) , 
 7.697.62 ( m , 2h ) , 7.567.52 ( m , 1h ) , 7.17 ( dd , j = 7.5 , 1.0 hz , 1h ) , 7.097.00 ( m , 2h ) , 5.295.22 
 ( m , 1h ) , 4.564.48 ( m , 2h ) , 3.983.91 ( m , 2h ) ; esi ms m / z 379 [ m  h ] ; hplc > 99% purity ( auc ) , tr = 15.4 
 min 
 ( method a ) .
compound ( )-34 was prepared according to a similar procedure described for the 
 synthesis of 28 .
mp 166170 c ; h nmr ( 500 mhz , dmso - d6 )  13.52 
 ( s , 1h ) , 10.96 ( s , 1h ) , 8.43 ( d , j = 8.5 hz , 1h ) , 
 7.95 ( dd , j = 8.0 , 1.5 hz , 1h ) , 7.567.50 
 ( m , 1h ) , 7.237.19 ( m , 2h ) , 7.177.12 ( m , 2h ) , 7.036.99 
 ( m , 1h ) , 4.114.01 ( m , 2h ) , 3.173.05 ( m , 2h ) , 2.89 
 ( t , j = 7.5 hz , 2h ) , 2.08 ( t , j = 
 7.5 hz , 2h ) , 1.811.74 ( m , 2h ) , 1.591.48 ( m , 2h ) ; esi 
 ms m / z 351 [ m + h ] ; 
 hplc > 99% purity ( auc ) , tr = 16.7 min 
 ( method a ) .
step a. to a 0 c cooled solution 
 of lialh4 in thf ( 1.0 m , 800 ml , 800 mmol ) in thf ( 800 
 ml ) was carefully 
 added ( 3ar,7as)-3a,4,7,7a - tetrahydro-1h - isoindole-1,3(2h)-dione ( 35 , 53.7 g , 0.35 mol ) portionwise .
an exotherm of 5 c 
 occurred upon each addition of 35 . upon complete addition
, 
 the mixture was allowed to warm to rt followed by heating at 70 c 
 for 16 h. the mixture was allowed to cool back to rt and then further 
 cooled to 0 c .
the reaction was carefully quenched by slow addition 
 of h2o ( 30 ml ) , 15% aqueous naoh solution ( 30 ml ) , followed 
 by another bolus of h2o ( 90 ml ) .
the rate of quenching 
 was done carefully so as to maintain an internal temperature below 
 25 c .
the aqueous filtrate was extracted with et2o ( 2  
 100 ml ) , and the organic extracts were combined and concentrated under 
 reduced pressure .
the resulting residue was purified using a kugelrorh 
 distillation apparatus to give ( 3ar,7as)-2,3,3a,4,7,7a - hexahydro-1h - isoindole as a clear , 
 colorless oil ( 19.45 g , 44% ) : h nmr ( 500 mhz , cdcl3 )  5.29 ( s , 2h ) , 3.88 ( bs , 1h ) , 3.26 ( m , 2h ) , 2.82 
 ( m , 2h ) , 2.412.19 ( m , 4h ) , 1.96 ( m , 2h ) .
step 
 b. to a 0 c cooled solution of ( 3ar,7as)-2,3,3a,4,7,7a - hexahydro-1h - isoindole ( 11.5 g , 93.5 mmol ) in ch2cl2 ( 200 
 ml ) was added boc2o ( 24.5 g , 112 mmol ) , and the mixture 
 was stirred at rt for 16 h. the mixture was washed with h2o ( 100 ml ) , brine ( 100 ml ) , dried over na2so4 , filtered , and concentrated under reduced pressure .
the residue 
 was purified by flash column chromatography ( isco combiflash rf unit , 
 330 g redisep column , 030% etoac in hexanes ) to give ( 3ar,7as)-tert - butyl 3a,4,7,7a - tetrahydro-1h - isoindole-2(3h)-carboxylate ( 36 ) as an oil ( 20.10 g , 49% ) : h nmr ( 500 mhz , cdcl3 )  5.64 ( s , 2h ) , 3.39 ( m , 2h ) , 3.20 ( m , 2h ) , 3.15 ( m , 
 2h ) , 2.232.19 ( m , 4h ) , 1.97 ( m , 2h ) , 1.57 ( s , 9h ) . step c. to a 0 c cooled mixture of ( 3ar,7as)-tert - butyl 3a,4,7,7a - tetrahydro-1h - isoindole-2(3h)-carboxylate ( 36 , 66.78 g , 224 mmol ) in ch3cn ( 600 ml ) , ccl4 ( 400 ml ) , and h2o ( 800 ml ) was added naio4 ( 192.3 g , 899 mmol ) followed by ruo2h2o ( 1.19 g , 8.94 mmol ) .
the mixture was stirred at rt for 24 h with 
 mechanical stirring and then filtered through celite .
the filter cake 
 was washed with 10% ch3oh in ch2cl2 ( 200 ml ) , and the biphasic mother liquor was separated .
the aqueous 
 phase was further extracted with ch2cl2 ( 3  
 150 ml ) , and the combined organic extracts were washed with h2o ( 100 ml ) , brine ( 100 ml ) , dried over na2so4 , filtered , and concentrated under reduced pressure . the residue 
 was filtered through a plug of silica gel using a ch3oh / ch2cl2 eluent system ( 2%10% ch3oh in ch2cl2 ) .
the filtrate was concentrated 
 under reduced pressure to give 2,2-((3s,4r)-1-(tert - butoxycarbonyl)pyrrolidine-3,4-diyl)diacetic 
 acid ( 37 ) as a solid ( 46.75 g , 72% ) : h nmr 
 ( 500 mhz , dmso - d6 )  12.2 ( s , 2h ) , 
 3.38 ( m , 2h ) , 3.02 ( m , 2h ) , 2.49 ( m , 2h ) , 2.32 ( m , 2h ) , 2.29 ( m , 2h ) , 
 1.42 ( s , 9h ) .
step d. to a suspension of 2,2-((3s,4r)-1-(tert - butoxycarbonyl)pyrrolidine-3,4-diyl)diacetic 
 acid ( 37 , 6.97 g , 24.31 mmol ) in ac2o ( 50 
 ml ) was added naoac ( 1.99 g , 24.31 mmol ) , and the mixture was heated 
 at 120 c for 3 h. the mixture cooled to rt and filtered through 
 celite .
the filter cake was washed with et2o ( 5  
 50 ml ) , and the mother liquor was concentrated under reduced pressure . 

the resulting residue was purified by flash column chromatography 
 ( isco combiflash rf unit , 120 g redisep column , 030% etoac 
 in hexanes ) to give ( 3ar,6as)-tert - butyl 5-oxohexahydrocyclopenta[c]pyrrole-2(1h)-carboxylate ( 38 ) as 
 a white foam ( 2.17 g , 40% ) : h nmr ( 500 mhz , cdcl3 )  3.69 ( m , 2h ) , 3.22 ( m , 2h ) , 2.91 ( m , 2h ) , 2.50 ( m , 2h ) , 
 2.17 ( m , 2h ) , 1.46 ( s , 9h ) .
step e. to a 78 
 c cooled solution 
 of ( 3ar,6as)-tert - butyl 5-oxohexahydrocyclopenta[c]pyrrole-2(1h)-carboxylate ( 38 , 22.35 g , 99.2 mmol ) in 
 thf ( 500 ml ) was slowly added a solution of lihmds in thf ( 1.0 m , 
 129 ml ) . the mixture continued to stir at 78 c for 30 
 min , and then a solution of 1,1,1-trifluoro - n - phenyl - n-((trifluoromethyl)sulfonyl)methanesulfonamide 
 ( 49.65 g , 139 mmol ) in thf ( 150 ml ) was slowly added .
the mixture 
 stirred for an additional 1 h at 78 c and was then allowed 
 to stir at rt for 2 h. the mixture was concentrated under reduced 
 pressure and the residue was purified by flash column chromatography 
 ( isco combiflash rf unit , 330 g redisep column , 050% etoac 
 in hexanes ) to give ( )-(3as,6as)-tert - butyl 5-(((trifluoromethyl)sulfonyl)oxy)-3,3a,6,6a - tetrahydrocyclopenta[c]pyrrole-2(1h)-carboxylate ( ( )-39 ) as a clear , viscous oil ( 1.56 g , quantitative ) : h nmr ( 500 mhz , cdcl3 )  5.58 ( s , 1h ) , 3.62 ( m , 
 1h ) , 3.53 ( m , 1h ) , 3.46 ( m , 2h ) , 3.19 ( m , 1h ) , 2.95 ( m , 2h ) , 2.46 
 ( m , 1h ) , 1.47 ( s , 9h ) . step f. to an n2 degassed mixture of 
 ( )-(3as,6as)-tert - butyl 5-(((trifluoromethyl)sulfonyl)oxy)-3,3a,6,6a - tetrahydrocyclopenta[c]pyrrole-2(1h)-carboxylate ( ( )-39 , 14.79 g , 41.4 mmol ) , 2-trifluoromethylphenylboronic acid 
 ( 19.70 g , 104 mmol ) , and a 2 m aqueous solution of na2co3 ( 250 ml ) in dme ( 500 ml ) was added pd(pph3)4 ( 4.80 g , 4.16 mmol ) .
the mixture was heated at 80 c 
 for 6 h , then cooled to rt and diluted with h2o ( 500 ml ) . 

the aqueous mixture was extracted with etoac ( 2  200 ml ) , and 
 the combined organic extracts were washed with h2o ( 200 
 ml ) , brine ( 200 ml ) , dried over na2so4 , filtered , 
 and concentrated under reduced pressure .
the residue was purified 
 by flash column chromatography ( isco combiflash rf unit , 330 g redisep 
 column , 010% etoac in hexanes ) to give ( )-(3ar,6as)-tert - butyl 5-(2-(trifluoromethyl)phenyl)-3,3a,6,6a - tetrahydrocyclopenta[c]pyrrole-2(1h)-carboxylate ( ( )-40 ) as a clear , viscous oil ( 13.70 g , 94% ) : h 
 nmr ( 500 mhz , cdcl3 )  7.65 ( m , 1h ) , 7.47 ( m , 2h ) , 
 7.25 ( m , 1h ) , 5.58 ( s , 1h ) , 3.853.42 ( m , 4h ) , 3.23 ( m , 1h ) , 
 2.98 ( m , 2h ) , 2.49 ( m , 1h ) , 1.47 ( s , 9h ) . step g. a mixture of ( )-(3ar,6as)-tert - butyl 5-(2-(trifluoromethyl)phenyl)-3,3a,6,6a - tetrahydrocyclopenta[c]pyrrole-2(1h)-carboxylate ( ( )-40 , 8.63 g , 24.41 mmol ) and 10% pd / c ( 1.57 g , wet , 10% w / w ) 
 in ch3oh ( 50 ml ) was subjected to an atmosphere of h2 gas ( 40 psi ) using a parr shaker apparatus at rt for 16 h. 
 the mixture was filtered through celite , and the filtrate was concentrated 
 under reduced pressure .
the resulting residue was purified by flash 
 column chromatography ( isco combiflash rf unit , 40 g redisep column , 
 030% etoac in hexanes ) to give ( 3ar,5r,6as)-tert - butyl 5-(2-(trifluoromethyl)phenyl)hexahydrocyclopenta[c]pyrrole-2(1h)-carboxylate ( 41 ) as a clear , viscous oil ( 0.910 g , 85% ) : h nmr ( 500 
 mhz , cdcl3 )  7.69 ( m , 1h ) , 7.51 ( m , 2h ) , 7.25 ( m , 
 1h ) , 3.49 ( m , 5h ) , 2.75 ( m , 2h ) , 2.92 ( m , 2h ) , 1.52 ( m , 2h ) , 1.48 
 ( s , 9h ) . step h. to a 0 c cooled solution 
 of ( 3ar,5r,6as)-tert - butyl 5-(2-(trifluoromethyl)phenyl)hexahydrocyclopenta[c]pyrrole-2(1h)-carboxylate ( 41 , 7.94 g , 22.32 mmol ) in ch2cl2 ( 60 ml ) was 
 added a 2 m hcl solution in et2o ( 60 ml ) , and the mixture 
 was allowed to stir at rt for 24 h. the mixture was diluted with et2o ( 200 ml ) and the precipitated product was filtered to give 
 ( 3ar,5r,6as)-5-(2-(trifluoromethyl)phenyl)octahydrocyclopenta[c]pyrrole hydrochloride ( 42 ) as a white solid 
 ( 5.90 g , 91% ) : h nmr ( 500 mhz , cdcl3 )  
 10.17 ( bs , 1h ) , 8.06 ( m , 1h ) , 7.59 ( m , 1h ) , 7.53 ( m , 1h ) , 7.27 ( m , 
 1h ) , 3.42 ( m , 2h ) , 3.38 ( m , 3h ) , 3.01 ( m , 2h ) , 2.36 ( m , 2h ) , 1.96 
 ( m , 2h ) ; esi ms m / z 256 [ m + h ] .
step i. to a solution of ( 3ar,5r,6as)-5-(2-(trifluoromethyl)phenyl)octahydrocyclopenta[c]pyrrole hydrochloride ( 42 , 0.640 g , 2.50 
 mmol ) in ch2cl2 ( 50 ml ) was added methyl 2-isocyanatobenzoate 
 ( 0.442 g , 2.50 mmol ) , and the mixture was stirred at rt for 16 h. 
 the mixture was concentrated under reduced pressure and the resulting 
 residue was purified by flash column chromatography ( isco combiflash 
 rf unit , 40 g redisep column , 030% etoac in hexanes ) to give 
 methyl 2-((3ar,5r,6as)-5-(2-(trifluoromethyl)phenyl)octahydrocyclopenta[c]pyrrole-2-carboxamido)benzoate as a white solid 
 ( 0.700 g , 64% ) : esi ms m / z 433 [ m 
 + h ] .
step j. to a solution of 
 methyl 2-((3ar,5r,6as)-5-(2-(trifluoromethyl)phenyl)octahydrocyclopenta[c]pyrrole-2-carboxamido)benzoate ( 0.700 g , 1.61 mmol ) 
 in ch3oh ( 20 ml ) and thf ( 20 ml ) was added aqueous 2 n 
 naoh ( 10 ml ) . the mixture stirred at rt for 16 h and concentrated 
 under reduced pressure .
the residue was diluted with h2o ( 25 ml ) and acidified to ph 5with 2 n hcl , and the resulting precipitate 
 was filtered to give 2-((3ar,5r,6as)-5-(2-(trifluoromethyl)phenyl)octahydrocyclopenta[c]pyrrole-2-carboxamido)benzoic acid ( 43 ) as a white solid ( 0.668 g , 98% ) : mp 157161 c ; h nmr ( 300 mhz , dmso - d6 )  
 13.46 ( br s , 1h ) , 10.79 ( s , 1h ) , 8.53 ( d , j = 8.5 
 hz , 1h ) , 7.96 ( dd , j = 8.0 , 1.5 hz , 1h ) , 7.80 ( m , 
 1h ) , 7.69 ( m , 1h ) , 7.60 ( m 1h ) , 7.48 ( m , 1h ) , 7.36 ( m , 1h ) , 6.99 ( m , 
 1h ) , 3.653.62 ( m , 2h ) , 3.473.38 ( m , 3h ) , 2.86 ( m , 
 2h ) , 2.272.22 ( m , 2h ) , 1.661.59 ( m , 2h ) ; esi ms m / z 419 [ m + h ] ; hplc 98.7% 
 purity ( auc ) , tr = 14.8 min ( method a ) . step a. to a solution of ( )-(3ar,6as)-tert - butyl 5-(2-(trifluoromethyl)phenyl)-3,3a,6,6a - tetrahydrocyclopenta[c]pyrrole-2(1h)-carboxylate ( ( )-40 , 120 mg , 0.34 mmol ) in ch2cl2 ( 3 
 ml ) was added a tfa ( 3 ml ) , and the resulting solution was stirred 
 at rt for 3 h. the residue was dissolved in ch2cl2 ( 25 ml ) and washed with saturated aqueous nahco3 solution 
 ( 25 ml ) , brine ( 25 ml ) , dried over na2so4 , filtered , 
 and concentrated under reduced pressure to provide ( )-(3as,6ar)-5-(2-(trifluoromethyl)phenyl)-1,2,3,3a,4,6a - hexahydrocyclopenta[c]pyrrole ( ( )-44 ) as an off - white solid 
 ( 0.146 mg , > 99% ) : h nmr ( 300 mhz , cdcl3 ) 
  
 9.21 ( br s , 1h ) , 8.18 ( br s , 1h ) , 7.67 ( d , j = 7.8 
 hz , 1h ) , 7.517.34 ( m , 3h ) , 5.57 ( s , 1h ) , 3.82 ( br 
 s , 1h ) , 3.623.54 ( m , 2h ) , 3.393.09 ( m , 
 4h ) , 2.622.56 ( m , 1h ) . step b. a solution of ( )-(3as,6ar)-5-(2-(trifluoromethyl)phenyl)-1,2,3,3a,4,6a - hexahydrocyclopenta[c]pyrrole ( ( )-44 , 159 mg , 0.43 mmol ) , 
 methyl 2-isocyanatobenzoate ( 91 mg , 0.51 mmol ) , and et3n ( 0.14 ml , 1.0 mmol ) in ch2cl2 ( 6 ml ) was 
 stirred at rt for 24 h. the mixture was diluted with saturated aqueous 
 nahco3 ( 30 ml ) and extracted with ch2cl2 ( 3  10 ml ) .
the combined organic extracts were washed 
 with brine , dried over na2so4 , filtered , and 
 concentrated under reduced pressure .
the resulting residue was chromatographed 
 over silica gel ( 0100% etoac in hexanes ) to give ( )-methyl 
 2-((3as,6ar)-5-(2-(trifluoromethyl)phenyl)-1,2,3,3a,4,6a - hexahydrocyclopenta[c]pyrrole-2-carboxamido)benzoate as an off - white solid 
 ( 0.114 g , 62% ) : h nmr ( 300 mhz , cdcl3 )  
 8.66 ( dd , j = 8.4 , 0.9 hz , 1h ) , 8.027.98 
 ( m , 1h ) , 7.667.64 ( m , 1h ) , 7.547.34 ( m , 4h ) , 6.996.93 
 ( m , 1h ) , 5.67 ( br s , 1h ) , 4.023.90 ( m , 4h ) , 3.813.67 
 ( m , 3h ) , 3.373.31 ( m , 1h ) , 3.162.97 ( m , 2h ) , 2.582.53 
 ( m , 1h ) .
step c. to a stirring solution of 
 ( )-methyl 
 2-((3as,6ar)-5-(2-(trifluoromethyl)phenyl)-1,2,3,3a,4,6a - hexahydrocyclopenta[c]pyrrole-2-carboxamido)benzoate ( 114 mg , 0.26 mmol ) 
 in ch3oh ( 4 ml ) and thf ( 4 ml ) was added a solution of 
 liohh2o ( 110 mg , 2.62 mmol ) in h2o ( 2 
 ml ) .
the mixture was stirred at rt for 4 h , was diluted with additional 
 h2o ( 10 ml ) , and was acidified to ph 6 with 2 n hcl .
the 
 resulting solids were collected by filtration and dried under reduced 
 pressure to provide ( )-2-((3as,6ar)-5-(2-(trifluoromethyl)phenyl)-1,2,3,3a,4,6a - hexahydrocyclopenta[c]pyrrole-2-carboxamido)benzoic acid ( ( )-45 ) as a white solid ( 0.085 mg , 79% ) : mp 148152 c ; h nmr ( 500 mhz , dmso - d6 )  
 13.50 ( bs , 1h ) , 10.74 ( s , 1h ) , 8.50 ( d , j = 8.5 hz , 
 1h ) , 7.96 ( m , 1h ) , 7.73 ( m , 1h ) , 7.64 ( m , 1h ) , 7.52 ( m , 2h ) , 7.44 
 ( m , 1h ) , 7.01 ( m , 1h ) , 5.68 ( s , 1h ) , 3.833.79 ( m , 1h ) , 3.643.55 
 ( m , 3h ) , 3.312.96 ( m , 3h ) ; esi ms m / z 415 [ m h ] ; hplc 97.5% purity 
 ( auc ) , tr = 13.6 min ( method a ) .
step a. to a solution of ( )-(3as,6ar)-5-(2-(trifluoromethyl)phenyl)-1,2,3,3a,4,6a - hexahydrocyclopenta[c]pyrrole ( ( )-44 , 0.680 g , 1.92 mmol ) 
 in ch3oh ( 25 ml ) was added pd / c ( 10% w / w , degussa type 
 e101 ne / w , 0.140 g ) . the mixture was subjected to an atmosphere of 
 h2 ( 50 psi ) at rt for 6 h and was filtered through celite . 

the filtrated was concentrated under reduced pressure , and the resulting 
 residue was purified by reversed phase column chromatography ( isco 
 c18 reversed phase gold column , 1030% ch3cn in 
 h2o with 0.05% tfa ) .
the resulting material was dissolved 
 in ch2cl2 and washed with saturated aqueous 
 nahco3 , dried over na2so4 , filtered , 
 and concentrated under reduced pressure to give ( 3ar,5s,6as)-5-(2-(trifluoromethyl)phenyl)octahydrocyclopenta[c]pyrrole ( 46 ) as a white solid ( 0.070 g , 14% ) : h nmr ( 300 mhz , cdcl3 )  7.61 ( d , j = 7.8 1h ) , 7.50 ( m , 2h ) , 7.307.24 ( m , 1h ) , 3.543.42 
 ( m , 1h ) , 3.323.26 ( m , 2h ) , 2.812.68 ( m , 2h ) , 2.512.46 
 ( m , 2h ) , 1.841.76 ( m , 4h ) ; esi ms m / z 256 [ m + h ] .
step b. to a solution of ( 3ar,5s,6as)-5-(2-(trifluoromethyl)phenyl)octahydrocyclopenta[c]pyrrole ( 46 , 0.030 g , 0.12 mmol ) in ch2cl2 ( 2 ml ) was added methyl 2-isocyanatobenzoate 
 ( 0.021 g , 0.12 mmol ) .
the mixture was stirred for 2 h and then chromatographed 
 over silica gel ( 050% etoac in hexanes ) to give methyl 2-((3ar,5s,6as)-5-(2-(trifluoromethyl)phenyl)octahydrocyclopenta[c]pyrrole-2-carboxamido)benzoate as a white solid 
 ( 0.052 g , quantitative ) : h nmr ( 300 mhz , cdcl3 )  10.53 ( s , 1h ) , 8.67 ( m , 1h ) , 8.01 ( dd , j = 8.0 , 1.6 hz , 1h ) , 7.627.46 ( m , 4h ) , 7.28 ( m , 1h ) , 6.996.94 
 ( m , 1h ) , 3.92 ( m , 5h ) , 3.793.67 ( m , 1h ) , 3.383.33 
 ( m , 2h ) , 3.07 ( m , 2h ) , 2.111.93 ( m , 4h ) ; esi ms m / z 433 [ m + h ] .
step c. to a solution of 2-((3ar,5s,6as)-5-(2-(trifluoromethyl)phenyl)octahydrocyclopenta[c]pyrrole-2-carboxamido)benzoate ( 0.052 g , 0.12 mmol ) 
 in thf ( 3 ml ) and ch3oh ( 1 ml ) was added a solution of 
 liohh2o ( 0.015 g , 0.36 mmol ) in h2o ( 1 
 ml ) .
the mixture was stirred at rt for 6 h , was acidified to ph 2 
 with 2 n hcl , and was poured into h2o .
the mixture was 
 extracted with ch2cl2 ( 30 ml ) , and the organic 
 extracts were washed with brine , dried over na2so4 , filtered , and concentrated under reduced pressure .
the residue 
 was chromatographed over silica gel ( 010% ch3oh 
 in ch2cl2 ) to give 2-((3ar,5s,6as)-5-(2-(trifluoromethyl)phenyl)octahydrocyclopenta[c]pyrrole-2-carboxamido)benzoic acid ( 48 ) as a white solid ( 0.049 g , 98% ) : mp 172174 c ; h nmr ( 300 mhz , cdcl3 )  13.48 ( bs , 1h ) , 
 10.74 ( bs , 1h ) , 8.51 ( d , j = 8.7 hz , 1h ) , 7.97 ( d , j = 8.1 hz , 1h ) , 7.69 ( m , 3h ) , 7.55 ( m , 1h ) , 7.41 ( m , 1h ) , 
 7.02 ( m , 1h ) , 3.76 ( m , 2h ) , 3.56 ( m , 1h ) , 3.25 ( dd , j = 10.8 , 4.8 hz , 2h ) , 3.04 ( m , 2h ) , 2.011.89 ( m , 4h ) ; esi 
 ms m / z 419 [ m + h ] . 

hplc > 99% purity ( auc ) , tr = 14.7 min 
 ( method a ) .
step a. to a solution of triphosgene 
 ( 0.148 g , 0.50 mmol ) in ch2cl2 ( 3.0 ml ) under 
 n2 , cooled to 78 c , was slowly added pyridine 
 ( 0.158 g , 2.00 mmol ) , and the resulting solution was stirred at 78 
 c for 10 min . a solution of ( 3ar,5r,6as)-5-(2-(trifluoromethyl)phenyl)octahydrocyclopenta[c]pyrrole hydrochloride ( 42
, 0.292 g , 1.00 
 mmol ) in ch2cl2 ( 2.0 ml ) was added , and the 
 resulting solution was stirred at 78 c for 30 min .
the 
 solution was warmed to rt and stirred for 2 h. the mixture was diluted 
 with 1 n hcl ( 8 ml ) and extracted with ch2cl2 ( 3  30 ml ) .
the combined organic extracts were washed with 
 saturated nahco3 solution ( 40 ml ) and concentrated under 
 reduced pressure .
the resulting residue was chromatographed over silica 
 gel ( 030% etoac in hexanes ) to give ( 3ar,5r,6as)-5-(2-(trifluoromethyl)phenyl)hexahydrocyclopenta[c]pyrrole-2(1h)-carbonyl chloride ( 49 ) as a light yellow solid ( 170 mg , 53% ) : h nmr 
 ( 300 mhz , dmso - d6 )  7.81 ( d , j = 8.4 hz , 1h ) , 7.697.60 ( m , 2h ) , 7.447.35 
 ( m , 1h ) , 3.853.75 ( m , 1h ) , 3.713.54 ( m , 2h ) , 3.513.43 
 ( m , 1h ) , 3.423.36 ( m , 1h ) , 2.912.75 ( m , 2h ) , 2.252.12 
 ( m , 2h ) , 1.701.55 ( m , 2h ) ; esi ms m / z 318 [ m + h ] .
step b. to a solution of give ( 3ar,5r,6as)-5-(2-(trifluoromethyl)phenyl)hexahydrocyclopenta[c]pyrrole-2(1h)-carbonyl chloride ( 49 , 0.100 g , 0.31 mmol ) in thf ( 1.8 ml ) were added i - pr2net ( 0.041 g , 0.31 mmol ) and methyl 2-amino-5-fluorobenzoate 
 ( 0.064 g , 0.37 mmol ) .
the resulting solution was heated at reflux 
 for 5 h. the mixture was diluted with h2o ( 30 ml ) and extracted 
 with etoac ( 4  30 ml ) .
the resulting residue was chromatographed 
 over silica gel ( 010% etoac in hexanes ) to give methyl 5-fluoro-2-((3ar,5r,6as)-5-(2-(trifluoromethyl)phenyl)octahydrocyclopenta[c]pyrrole-2-carboxamido)benzoate as a light orange 
 film ( 101 mg , crude ) : esi ms m / z 451 [ m + h ] .
step c. to a solution 
 of methyl 5-fluoro-2-((3ar,5r,6as)-5-(2-(trifluoromethyl)phenyl)octahydrocyclopenta[c]pyrrole-2-carboxamido)benzoate ( 0.101 g , 0.22 mmol ) 
 in thf ( 4.4 ml ) and ch3oh ( 2.3 ml ) was added a solution 
 of liohh2o ( 0.094 g , 2.24 mmol ) in h2o 
 ( 1.2 ml ) .
the mixture was stirred at rt for 18 h , was then acidified 
 to ph 5 with 2 n hcl , and was diluted with h2o ( 20 ml ) . 

the aqueous mixture was extracted with etoac ( 3  30 ml ) , and 
 the combined organic extracts were concentrated under reduced pressure . 

the resulting residue was chromatographed by reverse phase column 
 ( isco redisep 12 g gold c18 reverse phase column , 0100% ch3cn in h2o ) to provide 5-fluoro-2-((3ar,5r,6as)-5-(2-(trifluoromethyl)phenyl)octahydrocyclopenta[c]pyrrole-2-carboxamido)benzoic acid ( 50 ) as a white solid ( 0.011 g , 12% ) : mp 176180 c ; h nmr ( 500 mhz , dmso - d6 )  
 13.83 ( br s , 1h ) , 10.65 ( br s , 1h ) , 8.578.51 ( m , 1h ) , 7.75 
 ( d , j = 8.5 hz , 1h ) , 7.697.59 ( m , 3h ) , 7.467.36 
 ( m , 2h ) , 3.673.58 ( m , 2h ) , 3.473.36 ( m , 3h ) , 2.902.81 
 ( m , 2h ) , 2.282.20 ( m , 2h ) , 1.681.58 ( m , 2h ) ; esi ms m / z 437 [ m + h ] ; hplc > 99% 
 purity ( auc ) , tr = 11.3 min ( method b ) .
compound 51 was prepared according to a similar 
 procedure described for the synthesis of 50 .
mp 176179 
 c ; h nmr ( 500 mhz , dmso - d6 )  13.56 ( s , 1h ) , 10.42 ( br s , 1h ) , 8.43 ( d , j = 9.0 hz , 1h ) , 7.75 ( d , j = 8.0 hz , 1h ) , 7.677.59 
 ( m , 2h ) , 7.43 ( d , j = 3.0 hz , 1h ) , 7.427.36 
 ( m , 1h ) , 7.18 ( dd , j = 9.5 , 3.0 hz , 1h ) , 3.75 ( s , 
 3h ) , 3.653.58 ( m , 2h ) , 3.463.36 ( m , 3h ) , 2.902.79 
 ( m , 2h ) , 2.282.19 ( m , 2h ) , 1.661.57 ( m , 2h ) ; esi ms m / z 449 [ m + h ] ; hplc > 99% 
 purity ( auc ) , tr = 11.2 min ( method b ) .
to a solution of methyl 2-amino-5-chlorobenzoate ( 0.058 
 g , 0.31 mmol ) in dmf ( 2.7 ml ) cooled to 10 c under n2 was added nah ( 60% in mineral oil , 0.019 g , 0.47 mmol ) , and 
 the resulting solution was stirred at 10 c for 20 min . 
 a solution of ( 3ar,5r,6as)-5-(2-(trifluoromethyl)phenyl)hexahydrocyclopenta[c]pyrrole-2(1h)-carbonyl chloride ( 49 , 0.100 g , 0.315 mmol ) in dmf ( 0.55 ml ) was added and the 
 mixture stirred at rt for 2 h. the mixture was carefully diluted with 
 h2o ( 30 ml ) , made acidic to ph 2 with 2 n hcl , and was 
 extracted with etoac ( 4  30 ml ) .
the combined organic extracts 
 were washed with brine ( 4  30 ml ) and concentrated under reduced 
 pressure .
the resulting residue was chromatographed over silica gel 
 ( 010% ch3oh in ch2cl2 with 
 0.1% hoac ) followed by reverse phase column chromatography ( isco gold 
 redisep 12 g c18 reverse phase column , 0100% ch3cn in h2o ) to give 5-chloro-2-((3ar,5r,6as)-5-(2-(trifluoromethyl)phenyl)octahydrocyclopenta[c]pyrrole-2-carboxamido)benzoic acid ( 52 ) as a white solid ( 21 mg , 23% ) : mp 188193 c ; h nmr ( 500 mhz , dmso - d6 )  
 13.92 ( bs , 1h ) , 10.85 ( bs , 1h ) , 8.56 ( d , j = 9.5 
 hz , 1h ) , 7.90 ( s , 1h ) , 7.76 ( d , j = 8.0 hz , 1h ) , 
 7.687.54 ( m , 3h ) , 7.427.35 ( m , 1h ) , 3.673.58 
 ( m , 2h ) , 3.483.35 ( m , 3h ) , 2.902.80 ( m , 2h ) , 2.282.19 
 ( m , 2h ) , 1.671.53 ( m , 2h ) ; esi ms m / z 453 [ m + h ] ; hplc > 99% purity ( auc ) , tr = 12.0 min ( method b ) .
compound 53 was prepared according to a similar 
 procedure described for the synthesis of 52 .
mp 175181 
 c ; h nmr ( 500 mhz , dmso - d6 )  14.09 ( bs , 1h ) , 11.09 ( bs , 1h ) , 8.77 ( d , j = 9.0 hz , 1h ) , 8.42 ( d , j = 2.5 hz , 1h ) , 8.04 ( dd , j = 9.0 , 2.5 hz , 1h ) , 7.77 ( d , j = 8.0 
 hz , 1h ) , 7.677.60 ( m , 2h ) , 7.427.37 ( m , 1h ) , 3.723.64 
 ( m , 2h ) , 3.523.46 ( m , 2h ) , 3.453.32 ( m , 1h ) , 3.20 
 ( s , 3h ) , 2.922.84 ( m , 2h ) , 2.282.20 ( m , 2h ) , 1.691.59 
 ( m , 2h ) ; esi ms m / z 497 [ m + h ] ; hplc > 99% purity ( auc ) , tr = 
 10.6 min ( method b ) .
step a. a solution of ( 3ar,5r,6as)-5-(2-(trifluoromethyl)phenyl)[c]pyrrole-2(1h)-carbonyl chloride ( 49 , 0.300 g , 0.94 mmol ) in 7 n nh3 in ch3oh ( 4.0 ml ) was stirred at rt for 1 h. the mixture was concentrated 
 under reduced pressure to provide ( 3ar,5r,6as)-5-(2-(trifluoromethyl)phenyl)hexahydrocyclopenta[c]pyrrole-2(1h)-carboxamide as a white 
 solid ( 0.323 g , > 99% ) : esi ms m / z 299 [ m + h ] .
step b. a mixture 
 of ( 3ar,5r,6as)-5-(2-(trifluoromethyl)phenyl)hexahydrocyclopenta[c]pyrrole-2(1h)-carboxamide ( 0.100 g , 0.33 
 mmol ) , methyl 2-chloronicotinate ( 0.087 g , 0.50 mmol ) , cs2co3 ( 0.134 g , 0.47 mmol ) , pd(oac)2 ( 0.022 g , 
 0.033 mmol ) , and racemic binap ( 0.042 g , 0.067 mmol ) in toluene ( 4 
 ml ) was heated at reflux for 2 h. the mixture cooled to rt and was 
 filtered through celite .
the filtrate was washed with brine ( 3  
 30 ml ) and concentrated under reduced pressure .
the resulting residue 
 was chromatographed over silica gel ( 05% ch3oh 
 in ch2cl2 with 0.01% nh4oh ) to give 
 methyl 2-((3ar,5r,6as)-5-(2-(trifluoromethyl)phenyl)octahydrocyclopenta[c]pyrrole-2-carboxamido)nicotinate as a light orange 
 film ( 0.047 g , 31% ) : h nmr ( 300 mhz , dmso - d6 )  10.41 ( br s , 1h ) , 8.69 ( dd , j = 4.8 , 1.8 hz , 1h ) , 8.32 ( dd , j = 7.8 , 1.8 hz , 
 1h ) , 7.61 ( d , j = 7.8 hz , 1h ) , 7.577.47 ( m , 
 2h ) , 7.317.27 ( m , 1h ) , 7.00 ( dd , j = 7.8 , 
 4.8 hz , 1h ) , 3.95 ( s , 3h ) , 3.843.74 ( m , 2h ) , 3.683.60 
 ( m , 2h ) , 3.583.43 ( m , 1h ) , 2.952.83 ( m , 2h ) , 2.432.32 
 ( m , 2h ) , 1.721.57 ( m , 2h ) ; esi ms m / z 434 [ m + h ] .
step c. to a solution of methyl 2-((3ar,5r,6as)-5-(2-(trifluoromethyl)phenyl)octahydrocyclopenta[c]pyrrole-2-carboxamido)nicotinate ( 0.039 g , 0.090 
 mmol ) in thf ( 4.0 ml ) and ch3oh ( 1.9 ml ) was added a solution 
 of liohh2o ( 0.037 g , 0.90 mmol ) in h2o 
 ( 1.1 ml ) .
the mixture was stirred at rt for 3 h , was then neutralized 
 with 2 n hcl , and was extracted with ch2cl2 ( 4 
  20 ml ) .
the combined organic extracts were concentrated under 
 reduced pressure and the resulting residue was chromatographed by 
 reverse phase column chromatography ( isco redisep gold 12 g c18 reverse 
 phase column , 060% ch3cn in h2o ) to 
 give 2-((3ar,5r,6as)-5-(2-(trifluoromethyl)phenyl)octahydrocyclopenta[c]pyrrole-2-carboxamido)nicotinic acid ( 54 ) as a white solid ( 0.021 mg , 55% ) : mp 129133 c ; h nmr ( 300 mhz , dmso - d6 )  
 8.458.30 ( m , 2h ) , 7.76 ( d , j = 7.8 hz , 1h ) , 
 7.707.60 ( m , 2h ) , 7.457.34 ( m , 1h ) , 7.177.09 
 ( m , 1h ) , 3.673.61 ( m , 2h ) , 3.523.46 ( m , 2h ) , 3.453.35 
 ( m , 2h ) , 2.84 ( m , 2h ) , 2.26 ( m , 2h ) , 1.67 ( m , 2h ) ; esi ms m / z 420 [ m + h ] . hplc >
99% 
 purity ( auc ) , tr = 13.6 min ( method c ) .
step a. to a solution of ( 3ar,5r,6as)-5-(2-(trifluoromethyl)phenyl)hexahydrocyclopenta[c]pyrrole-2(1h)-carbonyl chloride ( 49 , 0.170 g , 0.53 mmol ) in thf ( 3.0 ml ) were added i - pr2net ( 0.064 g , 0.53 mmol ) and methyl 4-aminonicotinate 
 ( 0.081 g , 0.53 mmol ) , and the resulting mixture was heated at reflux 
 for 4 h. the mixture was cooled to rt , was diluted with h2o ( 20 ml ) , and was extracted with etoac ( 3  30 ml ) .
the resulting 
 residue was chromatographed over silica gel ( 05% ch3oh in ch2cl2 with 0.1% nh4oh ) to 
 give methyl 4-((3ar,5r,6as)-5-(2-(trifluoromethyl)phenyl)octahydrocyclopenta[c]pyrrole-2-carboxamido)nicotinate as a white solid 
 ( 0.140 g , 60% ) : h nmr ( 300 mhz , dmso - d6 )  10.46 ( br s , 1h ) , 8.98 ( d , j = 0.3 hz , 1h ) , 8.53 ( d , j = 6.0 hz , 1h ) , 8.46 ( d , j = 6.3 hz , 1h ) , 7.79 ( d , j = 8.1 hz , 1h ) , 
 7.687.59 ( m , 2h ) , 7.437.35 ( m , 1h ) , 3.91 ( s , 3h ) , 
 3.753.61 ( m , 2h ) , 3.523.35 ( m , 3h ) , 2.942.81 
 ( m , 2h ) , 2.312.17 ( m , 2h ) , 1.721.56 ( m , 2h ) ; esi ms m / z 434
step b. to a mixture of methyl 4-((3ar,5r,6as)-5-(2-(trifluoromethyl)phenyl)octahydrocyclopenta[c]pyrrole-2-carboxamido)nicotinate ( 0.138 g , 0.31 
 mmol ) in thf ( 6.2 ml ) and ch3oh ( 3.2 ml ) was added a solution 
 of liohh2o ( 0.130 g , 3.11 mmol ) in h2o 
 ( 1.6 ml ) .
the mixture was stirred at rt for 3 h , was then acidified 
 to ph 4 with 2 n hcl , and was diluted with h2o ( 50 ml ) . 

the resulting solids were collected by filtration and dried to provide 
 4-((3ar,5r,6as)-5-(2-(trifluoromethyl)phenyl)octahydrocyclopenta[c]pyrrole-2-carboxamido)nicotinic acid ( 55 ) as a light yellow solid ( 0.130 g , > 99% ) : mp 245255 c 
 dec ; h nmr ( 500 mhz , dmso - d6 )  8.92 ( m , 1h ) , 8.53 ( d , j = 6.5 hz , 1h ) , 
 8.44 ( d , j = 7.5 hz , 1h ) , 7.76 ( d , j = 8.0 hz , 1h ) , 7.677.59 ( m , 2h ) , 7.427.36 ( m , 1h ) , 
 3.753.62 ( m , 2h ) , 3.532.79 ( m , 4h ) , 2.87 ( m , 2h ) , 
 2.27 ( m , 2h ) , 1.67 ( m , 2h ) ; esi ms m / z 420 [ m + h ] ; hplc > 99% purity ( auc ) , tr = 12.5 min ( method g ) .
step a. to a 0 c cooled solution 
 of h2so4 ( 0.5 ml ) in ch3oh ( 5 ml ) 
 was slowly added 4-amino-6-methylnicotinic acid ( 0.200 g , 1.31 mmol ) , 
 and the mixture was heated at reflux for 16 h. the mixture was cooled 
 to rt and was poured into ice  water and neutralized with solid 
 na2co3 . the aqueous mixture was extracted with 
 ch2cl2 ( 3  30 ml ) and the organic extracts 
 were dried over na2so4 , filtered , and concentrated 
 to give methyl 4-amino-6-methylnicotinate as an off - white solid ( 0.120 
 g , 54% ) , which was used as is in the next step .
step 
 b. to a solution of methyl 4-amino-6-methylnicotinate ( 0.120 
 g , 0.72 mmol ) in dmf ( 10 ml ) cooled to 0 c was added nah ( 60% 
 in mineral oil , 0.035 g , 0.86 mmol ) and the resulting solution was 
 stirred at 0 c for 30 min .
a solution of ( 3ar,5r,6as)-5-(2-(trifluoromethyl)phenyl)hexahydrocyclopenta[c]pyrrole-2(1h)-carbonyl chloride ( 2 , 0.229 g , 0.72 mmol ) in dmf ( 2 ml ) was added and the mixture 
 stirred at rt for 2 h. the mixture was carefully diluted with h2o ( 30 ml ) and extracted with etoac ( 4  30 ml ) .
the combined 
 organic extracts were washed with brine ( 4  30 ml ) and concentrated 
 under reduced pressure .
the resulting residue was chromatographed 
 over silica gel ( 010% ch3oh in ch2cl2 ) to give methyl 2-(6-methyl-4-((3ar,5r,6as)-5-(2-(trifluoromethyl)phenyl)octahydrocyclopenta[c]pyrrole-2-carboxamido)pyridin-3-yl)-2-oxoacetate 
 as a white solid ( 0.043 g , 13% ) .
step c. to 
 a solution of methyl 2-(6-methyl-4-((3ar,5r,6as)-5-(2-(trifluoromethyl)phenyl)octahydrocyclopenta[c]pyrrole-2-carboxamido)pyridin-3-yl)-2-oxoacetate 
 ( 0.040 g , 0.080 mmol ) in thf ( 3 ml ) was added a solution of liohh2o ( 0.010 g , 0.24 mmol ) in h2o ( 2 ml ) .
the mixture 
 was stirred at rt for 24 h , was then carefully neutralized with 2 
 n hcl , and was extracted with ch2cl2 ( 3  
 30 ml ) .
the combined organic extracts were concentrated under reduced 
 pressure and the resulting residue was chromatographed over silica 
 gel ( 010% ch3oh in ch2cl2 ) to give 2-(6-methyl-4-((3ar,5r,6as)-5-(2-(trifluoromethyl)phenyl)octahydrocyclopenta[c]pyrrole-2-carboxamido)pyridin-3-yl)-2-oxoacetic 
 acid ( 56 ) as a light - yellow solid ( 0.020 g , 52% ) : h nmr ( 300 mhz , dmso - d6 )  
 8.78 ( m , 1h ) , 8.35 ( m , 1h ) , 7.77 ( m , 3h ) , 7.36 ( m , 1h ) , 3.68 ( m , 2h ) , 
 3.483.29 ( m , 7h ) , 2.56 ( m , 3h ) , 2.26 ( m , 2h ) , 1.55 ( m , 2h ) ; 
 esi ms m / z 434 [ m + h ] ; hplc 97.2% purity ( auc ) , tr = 13.9 
 min ( method c ) .
compound 57 was prepared according 
 to a similar procedure described for the synthesis of 56 .
mp 175181 c ; h nmr ( 300 mhz , dmso - d6 )  10.30 ( bs , 1h ) , 9.27 ( bs , 1h ) , 7.79 
 ( m , 1h ) , 7.64 ( m , 2h ) , 7.39 ( m , 2h ) , 3.72 ( m , 2h ) , 3.69 ( m , 2h ) , 2.89 
 ( m , 2h ) , 2.26 ( m , 2h ) , 1.62 ( m , 2h ) , 1.26 ( m , 2h ) ; esi ms m / z 421 [ m + h ] ; hplc 95.2% 
 purity ( auc ) , tr = 14.9 min ( method c ) .
step a. to mixture of ( 3ar,5r,6as)-5-(2-(trifluoromethyl)phenyl)hexahydrocyclopenta[c]pyrrole-2(1h)-carbonyl chloride ( 49 , 50 mg , 0.15 mmol ) and et3n ( 60 l , 0.56 
 mmol ) in dmf ( 4 ml ) was added methyl 2-aminoacetate hydrochloride 
 ( 24 mg , 0.189 mmol ) .
the resulting mixture was stirred at rt for 18 
 h and then concentrated under reduced pressure to give crude methyl 
 2-((3ar,5r,6as)-5-(2-(trifluoromethyl)phenyl)octahydrocyclopenta[c]pyrrole-2-carboxamido)acetate ( 0.055 g ) , which was 
 used as is in the next step : esi ms m / z 371 [ m + h ] .
step b. to a mixture 
 of crude methyl 2-((3ar,5r,6as)-5-(2-(trifluoromethyl)phenyl)octahydrocyclopenta[c]pyrrole-2-carboxamido)acetate ( 0.055 g , 0.14 mmol ) 
 in thf ( 2 ml ) was added a solution of liohh2o ( 57 
 mg , 1.35 mmol ) in h2o ( 2 ml ) , and the resulting mixture 
 was stirred at rt for 2 h. the mixture was acidified to ph 6 with 
 2 n hcl and extracted with ch2cl2 ( 3  
 50 ml ) .
the combined organic extracts were dried over na2so4 , filtered , and concentrated under reduced pressure . 

the resulting residue was chromatographed over silica gel ( 12 g redisep 
 column , 010% ch3oh in ch2cl2 with 0.1% nh4oh ) to give 2-((3ar,5r,6as)-5-(2-(trifluoromethyl)phenyl)octahydrocyclopenta[c]pyrrole-2-carboxamido)acetic acid ( 58 ) as a white solid ( 0.028 g , 55% ) : 173176 c ; h nmr ( 300 mhz , dmso - d6 )  7.747.59 
 ( m , 3h ) , 7.447.35 ( m , 1h ) , 6.29 ( m , 1h ) , 3.613.00 
 ( m , 7h ) , 2.74 ( m , 2h ) , 2.23 ( m , 2h ) , 1.53 ( m , 2h ) ; esi ms m / z 357 [ m + h ] ; hplc > 99% 
 purity ( auc ) , tr = 16.4 min ( method b ) .
compound ( s)-59 was prepared according to a similar procedure described for the 
 synthesis of 58 .
mp 138141 c ; h nmr ( 300 mhz , dmso - d6 )  7.787.56 
 ( m , 3h ) , 7.497.28 ( m , 1h ) , 6.22 ( m , 1h ) , 3.93 ( m , 1h ) , 3.503.23 
 ( m , 5h ) , 2.86 ( m , 2h ) , 2.20 ( m , 2h ) , 1.56 ( m , 2h ) , 1.341.13 
 ( m , 3h ) ; esi ms m / z 371 [ m + h ] ; hplc 98.5% purity ( auc ) , tr = 
 12.0 min ( method b ) . compound ( r)-60 was prepared according to a similar procedure described for the 
 synthesis of 58 .
mp 141145 c ; h nmr ( 300 mhz , dmso - d6 )  7.787.56 
 ( m , 3h ) , 7.497.28 ( m , 1h ) , 6.17 ( m , 1h ) , 389 ( m , 1h ) , 3.503.20 
 ( m , 5h ) , 2.79 ( m , 2h ) , 2.21 ( m , 2h ) , 1.56 ( m , 2h ) , 1.27 ( m , 3h ) ; esi 
 ms m / z 371 [ m + h ] ; 
 hplc 97.0% purity ( auc ) , tr = 11.9 min 
 ( method b ) . compound ( s)-61 was prepared according to a similar procedure described for the 
 synthesis of 58 .
mp 109114 c ; h nmr ( 300 mhz , dmso - d6 )  7.67 
 ( m , 3h ) , 7.49 ( m , 3h ) , 7.34 ( m , 3h ) , 6.55 ( m , 1h ) , 5.06 ( m , 1h ) , 3.503.20 
 ( m , 5h ) , 2.78 ( m , 2h ) , 2.34 ( m , 2h ) , 1.62 ( m , 2h ) ; esi ms m / z 433 [ m + h ] ; hplc 98.6% 
 purity ( auc ) , tr = 16.3 min ( method b ) .
compound ( r)-62 was prepared according to a similar procedure described for the 
 synthesis of 58 .
mp 109112 c ; h nmr ( 300 mhz , dmso - d6 )  7.68 
 ( m , 3h ) , 7.42 ( m , 3h ) , 7.297.16 ( m , 3h ) , 6.40 ( m , 1h ) , 4.90 
 ( m , 1h ) , 3.523.21 ( m , 5h ) , 2.75 ( m , 2h ) , 2.27 ( m , 2h ) , 1.56 
 ( m , 2h ) ; esi ms m / z 433 [ m + h ] ; hplc 98.3% purity ( auc ) , tr = 
 16.3 min ( method b ) . analogue binding affinities for rbp4 were 
 measured using our previously reported scintillation proximity assay 
 ( spa ) , which measured competitive displacement of radiolabeled retinol .
briefly , human rbp4 was biotinylated using the 
 ez - link sulfo - nhs - lc - biotinylation kit from pierce ( rockford , il ) 
 following the manufacturer s recommendations .
binding experiments 
 were performed in a final assay volume of 100 l per well in 
 spa buffer ( 1 pbs , ph 7.4 , 1 mm edta , 0.1% bsa , 0.5% chaps ) . 

the reaction mix contained 10 nm h - retinol ( 48.7 ci / mmol ; 
 perkinelmer , waltham , ma ) , 0.3 mg / well streptavidin - pvt beads , 50 
 nm biotinylated rbp4 .
radio counts were measured using 
 chameleon plate reader ( hidex oy , turku , finland ) following overnight 
 incubation at 4 c .
the ability of compounds to antagonize the retinol - dependent 
 rbp4-ttr interaction was measured using the htrf assay .
maltose binding protein - tagged rbp4 expressed 
 in e. coli and untagged ttr were used in this assay . 

ttr was directly labeled with eu cryptate - nhs using the 
 htrf cryptate labeling kit from cisbio ( bedfored , ma ) following the 
 manufacturer s recommendations .
the htrf assay was performed 
 in a final assay volume of 16 l per well .
the reaction buffer 
 contained 10 mm tris - hcl , ph 7.5 , 1 mm dtt , 0.05% np-40 , 0.05% prionex , 
 6% glycerol , and 400 mm kf .
each reaction contained 60 nm mbp - rbp4 
 and 2 nm ttr - eu along with 26.7 nm anti - mbp antibody conjugated with 
 d2 ( cisbio ) .
the rbp4-ttr interaction was stimulated by the addition 
 of 1 m all - trans retinol .
htrf signal was 
 measured in the spectramax m5e multimode plate reader ( molecular devices , 
 sunnyvale , ca ) following the overnight 4 c incubation .
fluorescence 
 was excited at 337 nm ; emission was measured at 668 and 620 nm with 
 75 s counting delay .
the tr - fret signal was expressed as the 
 ratio of fluorescence intensity : ( flu668/flu620 )  10  000 .
 accumulation of lipofuscin in the 
 retina is associated with pathogenesis 
 of atrophic age - related macular degeneration and stargardt disease . 
 
 lipofuscin bisretinoids ( exemplified by n - retinylidene - n - retinylethanolamine ) seem to mediate lipofuscin toxicity . 
 
 synthesis of lipofuscin bisretinoids depends on the influx of retinol 
 from serum to the retina . 
 compounds antagonizing the retinol - dependent 
 interaction of retinol - binding protein 4 ( rbp4 ) with transthyretin 
 in the serum would reduce serum rbp4 and retinol and inhibit bisretinoid 
 formation . 
 we recently showed that a1120 ( 3 ) , a potent 
 carboxylic acid based rbp4 antagonist , can significantly reduce lipofuscin 
 bisretinoid formation in the retinas of abca4/ mice . 
 as part of the nih 
 blueprint neurotherapeutics network project we undertook the in vitro exploration to identify novel conformationally flexible and constrained 
 rbp4 antagonists with improved potency and metabolic stability . 
 we 
 also demonstrate that upon acute and chronic dosing in rats , 43 , a potent cyclopentyl fused pyrrolidine antagonist , reduced 
 circulating plasma rbp4 protein levels by approximately 60% . 
Introduction
Chemistry
Results and Discussion
Conclusions
Experimental
Section