upon developing a rapid 
 and efficient synthesis of 2,1-borazaronaphthalenes 
 starting from simple , readily available starting materials , we subsequently developed the suzuki 
these studies 
 demonstrated the stability of these azaborines to transition metal catalysis and allowed access to functionalized 
 molecules that could have applications in medicinal chemistry and/or materials science .
during the course of this latter study , we first developed conditions 
 for the cross - coupling of n - h and n - alkyl 3-bromo - b - alkyl-2,1-borazaronaphthalenes ( eq 1).1 at the same time , 
 we investigated the cross - coupling of b - aryl 2,1-borazaronaphthalenes 
 with potassium ( hetero)aryltrifluoroborates ( eq 1 ) , which was perceived at the outset to present a challenge . in this 
 cross - coupling
, both the azaborine and the aryltrifluoroborate would 
 appear to have the potential to serve as a nucleophilic component 
 in cross - coupling reactions , unlike the cross - coupling of the b - alkyl 2,1-borazaronaphthalenes , 
 where the aryltrifluoroborate was expected to react preferentially 
 on the basis of a more facile , rate - determining transmetalation .
thus , during cross - coupling events , aryltrifluoroborates 
 are slowly converted to the corresponding tricoordinate boronic acids , 
 which are believed to be the active transmetalation species and are capable of undergoing transmetalation 
 by interacting with an oxo - palladium species to form a tetracoordinate 
  ate  complex .
similarly , 
 the boron of the 2,1-borazaronaphthalene is also formally tricoordinate , 
 although in this instance contribution of electron density from the 
 nitrogen lone - pair would render the boron less lewis acidic , in consonance 
 with the aromaticity of the borazine substructure .
in fact , 
 attempts to cross - couple an n - substituted 
 3-bromo-2-aryl-2,1-borazaronaphthalene 
 with potassium phenyltrifluoroborate resulted in complete conversion 
 to a side product under the standard reaction conditions . upon lowering 
 the reaction temperature to room temperature ,
a mixture of the desired 
 product and the same unknown side product was observed . after removing 
 the nucleophilic component of the reaction ( i.e. , the potassium phenyltrifluoroborate ) , 
 unreacted starting material and the same unknown side product were 
 evident after 24 h , demonstrating that the phenyltrifluoroborate was 
 not directly involved in this reaction .
paetzold previously 
 reported that the aryl group of 2-pentafluorophenyl-2,1-borazaronaphthalene 
 could be displaced upon heating in koh / meoh , forming the corresponding 
 2-methoxy-2,1-borazaronaphthalene .
on 
 the basis of the chemical shift in the b nmr of our cross - coupling 
 reactions , formation of a 2,1-borazaronaphthalene product containing 
 a b - or bond appeared possible ; however , stability tests , in addition 
 to the successful cross - coupling of other brominated azaborines , demonstrated 
 the inherent stability of the brominated 2,1-borazaronaphthalenes 
 to the basic conditions of the cross - coupling .
these results suggested 
 that the process observed was palladium mediated . by realizing 
 that the brominated 2,1-borazaronaphthalene can serve 
 as both the nucleophile and electrophile in a cross - coupling reaction , 

after oxidative 
 addition of the c  br bond to the palladium catalyst , transmetalation 
 of the aryl group on boron of the borazine would lead to c 
this 
 self - arylation proceeded in low yield under the initial conditions , 
 providing the product in only 13% yield ( eq 2 ) . on the basis of this initial result
, we sought to determine if 
 this transformation could be developed into a viable synthetic protocol 
 for the construction of 3-aryl-2,1-borazaronaphthols2
optimization of the self - arylation 
 of 1 was conducted 
 with the aid of high - throughput experimentation ( hte ) .
a 24-well plate was designed to test the ligand , 
 base , and ratio of solvent to water in the self - arylation .
the 
 product - to - internal standard ( p / is ) ratios were calculated to determine 
 the relative amount of product formed in each microscale reaction 
 ( 10 mol ) .
reaction conditions : 1 
 mol % aminobiphenyl 
 pd -cl dimer , 2 mol % ligand , 1.0 equiv of 1-allyl-3-bromo-2-phenyl-2,1-borazaronaphthalene , 
 3.0 equiv of base , rt , 18 h. during the transmetalation step of a cross - coupling involving 
 organoborons , 
 an oxo - palladium complex interacts with the vacant orbital on boron . 
 because the lewis acidity of the boron center in 2,1-borazaronaphthalenes 
 is attenuated by electron donation from nitrogen , transmetalation 
 is more difficult .
jutand and hartwig have both reported that hydroxide bases provide 
 the best conversion to product for cross - couplings in which the rate - determining 
 step is the transmetalation .
hydroxide bases increase the formation 
 of the more reactive arpd(oh)l complex , which undergoes transmetalation 
 at a faster rate relative to the corresponding arpd(x)l complex . utilizing 
 this information ,
csoh was employed as a base in the screen , providing 
 the largest increase in conversion across the board when compared 
 with results using cs2co3 . of the ligands 

tested , sphos provided the highest p / is ratio with 
 a solvent system of 9:1 cyclopentyl methyl ether ( cpme)/h2o .
further optimization showed that switching the solvent from cpme 
 to thf resulted in higher conversion to the desired product , and switching 
 the base from csoh to koh had no major effect on the reaction .
the 
 ( sphos)(aminobiphenyl ) palladium chloride precatalyst ( commercially 
 available sphos - pd - g2 , figure 2 ) was employed 
 as the palladium source when the self - arylation was scaled from the 
 hte screen .
varying the group on nitrogen does not affect the self - arylation as 
 the corresponding products are obtained in yields up to 98% ( table 1 ) .
the scalable nature of the coupling was illustrated 
 by performing the reaction on 2.5 mmol , which afforded the self - arylated 
 product in 96% yield while at the same time allowing half of the palladium 
 loading ( 1 mol % ) used in smaller scale reactions .
reaction 
 performed on a 2.5 mmol 
 scale with 1 mol % sphos - pd - g2 reaction conditions ( unless otherwise 
 noted ) : 1.0 equiv of 1-alkyl-3-bromo-2-phenyl-2,1-borazaronaphthalene , 
 2 mol % sphos - pd - g2 , 3.0 equiv of base , 9:1 thf / h2o , rt , 
 18 h. the isolation of 2,1-borazaronaphthols 
 has not been reported in 
 the literature .
in fact , until this study , 2,1-borazaronaphthol was 
 only shown to exist in basic ethanol solution , forming the corresponding 
 anhydride in the solid state ( eq 3 ) . in the current study , steric encumbrance provided 
 by substitution of the azaborine at the 1 and 3 positions
apparently 
 inhibits anhydride formation , allowing the corresponding 2,1-borazaronaphthols 
 to be isolated in high yield.3 although 2,1-borazaronaphthols 
 were found to decompose on silica 
 gel , surprisingly , they can be converted to their respective anhydrides 
 ( to various extents ) upon column chromatography with florisil .
the 
 formation of the anhydride was confirmed by passing 2d through florisil and obtaining an x - ray structure of the product 
 ( figure 3 ) .
an array of 1-allyl-2-(hetero)aryl-3-bromo-2,1-borazaronaphthalenes 
 was subsequently subjected to the 
 standard conditions to ascertain the scope of this novel process ( table 2 ) .
after purification with florisil , many of the 
 products were isolated as mixtures of the anhydride and the monomer . 

fortunately , it was discovered that subjecting the anhydride to basic 
 aqueous thf ( 3 equiv koh in thf / h2o ) converted the anhydride 
 to the corresponding 2,1-borazaronaphthol .
aryl groups with both electron - donating 
 ( entries 1 , 2 , and 6 ) and electron - withdrawing groups ( entries 35 ) 
 underwent self - arylation in yields up to 90% .
the aryl group can be 
 substituted ortho- ( entry 6 ) , meta- ( entries 23 ) , and para- ( entries 1 , 45 ) 
 to afford the desired products in high yield .
the enhanced reactivity 
 of the azaborinyl bromide relative to an aryl halide is evident through 
 self - arylation of the 3-bromo-2,1-borazaronaphthalene that has an 
 embedded aryl chloride ( entry 3 ) .
further , heteroaryl groups , specifically 
 thienyl and dibenzofuryl , can be transferred to the 3-position in 
 yields of 85% and 63% , respectively ( entries 89 ) .
reported 
 as the ratio of anhydride : monomer reaction conditions ( unless otherwise 
 noted ) : 1.0 equiv of 1-allyl-2-aryl-3-bromo-2,1-borazaronaphthalene , 
 2 mol % sphos - pd - g2 , 3.0 equiv of base , 9:1 thf / h2o , rt , 
 18 h. to probe the mechanism 
 of the self - arylation , a crossover experiment 
 was conducted with two brominated azaborines possessing similar substitution 
 patterns . subjecting both azaborines to the same reaction conditions 
 resulted in complete conversion of both starting materials .
hplc analysis 
 showed formation of all four possible arylated products ( self - arylated 
 and cross - arylated ) in approximately equal amounts , confirming that 
 the self - arylation observed is an intermolecular process ( eq 4).4 an n - substituted b - alkyl 3-bromo-2,1-borazaronaphthalene 
 was subjected 
 to the developed self - arylation conditions . because the calkyl 
b bond is stronger than the caryl  b bond , transmetalation is more challenging .
as expected , 
 the azaborine did not undergo self - alkylation , and only unreacted 
 starting material was observed after 18 h ( eq 5).5 further , subjecting 
 the free n - h 3-bromo-2-phenyl-2,1-borazaronaphthalene 
 to the reaction conditions did not produce the self - arylated product 
 ( eq 6 ) .
the starting material was consumed in 
 the reaction but an array of products was observed by crude nmr.6 this result suggested 
 that substitution on nitrogen is required 
 for the self - arylation to proceed smoothly , creating an environment 
 suitable for self - arylation .
several lines of investigation were carried 
 out in an attempt to rationalize this phenomenon .
one contributing 
 factor in these systems was postulated to be the difference in strength 
 of the b 
caryl bond in the n - h 
 versus the n - substituted azaborines . to clarify this 
 hypothesis , a series of calculations , conducted at the b3lyp/6 - 31g(d , p ) 
 level of theory , were completed to determine the relative bond order 
 of the b 
caryl bond 
 was weaker in the case of the n - allyl 2,1-borazaronaphthalene . 

thus , the substituent on nitrogen in this system causes the arene 
 to rotate such that it is no longer in plane with the azaborine , thereby 
 decreasing molecular orbital overlap between the empty p orbital on 
 boron of the azaborine and the arene , weakening the b 
, the free n - h 2,1-borazaronaphthalene 
 is nearly planar , resulting in better orbital overlap and a stronger 
 b  caryl bond .
optimized 
 geometry and bond orders for n - allyl 
 and n - h 2,1-borazaronaphthalenes ( calculated at the 
 b3lyp/6 - 31g(d , p ) level of theory ) .
another factor postulated was the ability of the boron to 
 interact 
 with an oxo - palladium species to facilitate the transmetalation process . 

miyaura cross - coupling reaction 
 has been postulated to proceed via the formation of a tetracoordinate 
  ate 
complex , in which the vacant orbital on boron 
 interacts with an oxo - palladium complex .
formation of the  ate  complex can be viewed as an 
 interaction between a lewis acidic boron source and the lewis basic 
 oxo - palladium species .
increasing the lewis acidity of the boron will 
 favor formation of the  ate 
the relative lewis acidities of the n - allyl and n - h 2,1-borazaronaphthalenes were therefore 
 calculated as a means to determine the suitability of these entities 
 to participate in the requisite lewis acid  base complex formation . 
 because substitution on nitrogen rotates the arene out of the plane 
 of the 2,1-borazaronaphthalene , the loss in molecular orbital overlap 
 results in a relative charge on the boron atom of the 1-allyl-2-phenyl-2,1-borazaronaphthalene 
 of 0.652 , which is significantly greater than that of the free n  h 
 2-phenyl-2,1-borazaronaphthalene ( 0.568 ) .
in further calculations , 
 the increased lewis acidity of the n - allyl 2,1-borazaronaphthalene 
 was also determined to favor the required  ate  complex 
 formation by 2 kcal / mol over that of the n  h congener 
 ( figure 5 ) .
this series of calculations , conducted 
 at the b3lyp / lanl2dz level of theory , used pme3 as a generic 
 ligand on palladium and a vinyl group as a generic coupling partner . 
 although the calculations do not provide information about the mechanism 
 of the transmetalation
, they do suggest that there is an increased 
 stability of the  ate 
complex for the n - allyl 2,1-borazaronaphthalene relative to that of the free n  h 
 2,1-borazaronaphthalene .
relative energies of formation of pd-ate 
 complexes 
 ( calculated at the b3lyp / lanl2dz level of theory ) . given that the aryl group in n - alkyl - b - aryl-3-bromo-2,1-borazaronaphthalenes was 
 subject to competitive 
 reaction in suzuki - type reactions ,
investigations were carried out 
 to determine how these systems could be otherwise manipulated in synthetically 
 useful ways .
although attempts to access 1,2,3-trisubstituted-2,1-borazaronaphthalenes 
 via cross - coupling of 1 with an external trifluoroborate 
 were unsuccessful because mixtures of cross - coupled and self - arylated 
 products were observed , the product of the self - arylation could be 
 reacted with a grignard reagent at elevated temperature to form the 
 desired trisubstituted azaborine in low yield ( eq 7).7 in more successful 
 efforts , kumada coupling between an aryl grignard 
 reagent and a brominated 2,1-borazaronaphthalene afforded the 1,2,3-trisubstituted-2,1-borazaronaphthalenes 
 in high yield with 1 mol % of the ( t - bu3p)(aminobiphenyl ) palladium chloride precatalyst ( commercially available t - bu3p - pd - g2 , table 3 ) .
ortho- , meta- , and para - substituted aryl grignard reagents proved to be successful nucleophiles 
 in the reaction , and the desired products were obtained in yields 
 up to 89% ( entries 24 ) .
further , the substituent on nitrogen 
 could be changed without loss of yield ( entry 5 ) . reaction conditions ( unless otherwise 
 noted ) : 1.0 equiv of 1-allyl-3-bromo-2-phenyl-2,1-borazaronaphthalene , 
 1.2 equiv of armgbr , 1 mol % t - bu3p - pd - g2 , 
 thf , 0 c to rt , 18 h. the next reaction investigated was the coupling of 1-benzyl-3,6-dibromo-2-phenyl-2,1-borazaronaphthalene 
 with 1 equiv of phb(oh)2 under slightly modified conditions 
 ( eq 8) .
the dibrominated azaborine underwent 
 self - arylation in addition to a second cross - coupling with the phenylboronic 
 acid , affording the desired product in 92% yield .
the product of this 
 dual cross - coupling was a 1,3,6-trisubstituted-2,1-borazaronaphthol , 
 building molecular complexity by functionalizing three different borazine 
 positions through a single operation . attempts to employ arylboronic 
 acids that were structurally different from the b - aryl group embedded 
 within the borazaronaphthalene resulted in a mixture of cross - coupled 
 products because no site - selectivity could be achieved in reactions 
 of the two incorporated bromides.8 to confirm that 
 the dibrominated azaborine underwent a dual cross - coupling , 
 a crystal structure was obtained for 6 ( figure 6 ) .
interestingly , the x - ray structure also reveals 
 that looking at the molecule with a 90 rotation such that it 
 is lying horizontal , the b 
n ring of the 2,1-borazaronaphthalene 
 is not completely planar , with the boron atom being located approximately 
 0.15  or 3.5 out of plane .
x - ray structure of 1-benzyl-3,6-diphenyl-2,1-borazaronaphthol 
 ( left ) . 
 rotated to show the nonplanarity of the b 
n ring without substituents 
 at 1 , 3 , and 6-positions ( right ) .
the self - arylation of n - substituted 3-bromo-2,1-borazaronaphthalenes 
 has been reported to proceed in high yield under mild reaction conditions . 

the products of the self - arylation are air- and moisture - stable 2,1-borazaronaphthols , 
 the first isolable examples of this class of azaborine . to the best 
 of our knowledge
, this self - arylation is the first report demonstrating 
 the ability of brominated azaborines to serve as both the nucleophile 
 and electrophile in cross - coupling reactions .
the 2,1-borazaronaphthols 
 are converted to their corresponding anhydrides upon purification 
 with florisil , but they can be hydrolyzed back to the 2,1-borazaronaphthols 
 by subjecting the anhydride to basic aqueous thf .
the corresponding 
 1,2,3-trisubstituted-2,1-borazaronaphthalenes can be afforded by performing 
 a kumada coupling with an aryl grignard reagent .
the overall value 
 of the synthetic method described herein can be highlighted by comparison 
 with the synthesis of isosteric naphthalene derivatives .
accessing 
 3-arylnaphth-2-ols through cross - coupling at the 3-position requires 
 protection and deprotection of the alcohol , whereas the self - arylation alleviates the need for protecting group 
 manipulation to afford the isosteric azaborine in a single step .
t - bu3p - pd - g2 and sphos - pd - g2 were synthesized 
 according to the literature .
thf was 
 dried using a j. c. meyer solvent system 
 with passage through two columns of activated alumina .
b nmr spectra 
 were obtained on a spectrometer equipped with the appropriate decoupling 
 accessories .
all b nmr chemical shifts were referenced 
 to external bf3oet2 ( 0.0 ppm ) with a negative 
 sign indicating an upfield shift .
data are presented as follows : chemical 
 shift ( ppm ) , multiplicity ( s = singlet , d = doublet , t = triplet , 
 m = multiplet , br = broad ) , coupling constant j ( hz ) 
 and integration .
analytical thin - layer chromatography ( tlc ) was performed 
 on tlc silica gel plates ( 0.25 mm ) precoated with a fluorescent indicator . 

hrms data were obtained 
 by either esi or ci using a tof mass spectrometer . for hrms of most 
 anhydrides ,
ionization of the sample resulted in dissociation to the 
 monomer , which was found within 5 ppm .
the 1-alkyl-2-aryl-3-bromo-2,1-borazaronaphthalenes were prepared 
 according to the literature . obtained as an off - white solid ( 0.4 mmol scale , 100 mg , 74% ) .
h nmr ( 500 mhz , acetone - d6 )  8.49 ( s , 1h ) , 7.777.73 ( m , 
 1h ) , 7.627.54 ( m , 2h ) , 7.38 ( d , j = 6.3 hz , 
 2h ) , 7.307.20 ( m , 3h ) , 6.035.94 ( m , 1h ) , 5.13 ( d , j = 10.3 hz , 1h ) , 4.91 ( d , j = 17.3 hz , 
 1h ) , 4.734.71 ( m , 2h ) , 2.36 ( s , 3h ) .
c nmr ( 125.8 
 mhz , acetone - d6 )  146.0 , 140.1 , 
 137.3 , 135.2 , 131.6 , 129.6 , 128.9 , 128.1 , 126.4 , 121.8 , 117.1 , 115.2 , 
 51.4 , 20.6 .
ir ( neat ) 3013 , 2920 , 1607 , 1367 , 918 , 
 764 cm . hrms ( ci ) m / z calc . for c18h18bbrn [ m + h ]
obtained as an off - white solid ( 0.74 mmol scale , 141 mg , 56% ) . 

h nmr ( 500 mhz , acetone - d6 )  8.50 ( s , 1h ) , 7.77 ( d , j = 7.8 hz , 1h ) , 7.637.50 ( m , 4h ) , 7.327.28 ( m , 1h ) , 
 7.217.16 ( m , 2h ) , 6.045.97 ( m , 1h ) , 5.14 ( dd , j = 10.5 , 1.2 hz , 1h ) , 4.91 ( dd , j = 17.4 , 
 1.2 hz , 1h ) , 4.714.69 ( m , 2h ) .
c nmr ( 125.8 mhz , 
 acetone - d6 )  162.8 ( d , j = 244 hz ) , 146.2 , 140.0 , 135.0 , 133.7 ( d , j = 8.8 hz ) , 129.7 , 129.0 , 126.4 , 122.0 , 117.1 , 115.3 , 114.3 ( d , j = 20.1 hz ) , 51.4 .
ir ( neat ) 3066 , 1595 , 1370 , 
 920 , 764 cm .
obtained as a yellow oil ( 1.7 mmol scale , 230 mg , 35% ) .
h nmr ( 500 mhz , acetone - d6 )  8.49 
 ( s , 1h ) , 7.777.73 ( m , 3h ) , 7.707.67 ( m , 2h ) , 7.627.56 
 ( m , 2h ) , 7.327.27 ( m , 1h ) , 6.005.95 ( m , 1h ) , 5.13 
 ( d , j = 10.5 hz , 1h ) , 4.90 ( d , j = 17.4 hz , 1h ) , 4.664.64 ( m , 2h ) .
c nmr ( 125.8 
 mhz , acetone - d6 )  146.5 , 139.8 , 
 134.7 , 132.1 , 129.8 , 129.4 ( q , j = 32 hz ) , 129.2 , 
 126.5 , 124.6 ( q , j = 271 hz ) , 124.0 ( q , j = 3.8 hz ) , 122.2 , 117.0 , 115.6 , 51.5 .
ir ( neat ) 
 2959 , 1323 , 1123 , 1071 , 832 , 764 cm . hrms ( ci ) m / z calc . for c18h14bbrf3n [ m ] 391.0355 , found 391.0345 .
obtained as a yellow oil ( 1.7 mmol scale , 505 mg , 88% ) .
h nmr ( 500 mhz , acetone - d6 )  8.48 
 ( s , 1h ) , 7.74 ( d , j = 7.8 hz , 1h ) , 7.597.53 
 ( m , 2h ) , 7.327.26 ( m , 4h ) , 7.19 ( d , j = 6.6 
 hz , 1h ) , 6.005.94 ( m , 1h ) , 5.12 ( dd , j = 
 10.5 , 1.2 hz , 1h ) , 4.90 ( dd , j = 17.4 , 1.2 hz , 1h ) , 
 4.704.68 ( m , 2h ) , 2.35 ( s , 3h ) .
c nmr ( 125.8 
 mhz , acetone - d6 )  146.1 , 140.0 , 
 136.4 , 135.1 , 132.0 , 129.6 , 129.0 , 128.5 , 128.5 , 127.4 , 126.4 , 121.8 , 
 117.0 , 115.3 , 51.4 , 20.9 .
ir ( neat ) 2980 , 1546 , 1367 , 
 763 , 744 cm .
hrms ( ci ) m / z calc . for c18h17bbrn [ m ] 337.0637 , found 337.0636 .
obtained as a yellow oil ( 1.14 mmol scale , 300 mg , 74% ) .
h nmr ( 500 mhz , acetone - d6 )  8.51 
 ( s , 1h ) , 7.78 ( dd , j = 7.8 , 1 hz , 1h ) , 7.637.56 
 ( m , 2h ) , 7.50 ( s , 1h ) , 7.427.39 ( m , 3h ) , 7.337.29 
 ( m , 1h ) , 6.035.98 ( m , 1h ) , 5.15 ( dd , j = 
 10.8 , 1.2 hz , 1h ) , 4.91 ( dd , j = 17.4 , 1.2 hz , 1h ) , 
 4.704.67 ( m , 2h ) .
c nmr ( 125.8 mhz , acetone - d6 )  146.4 , 139.8 , 134.8 , 133.3 , 131.0 , 
 129.8 , 129.7 , 129.4 , 129.2 , 127.8 , 126.5 , 122.1 , 117.1 , 115.5 , 51.5 .
hrms ( ci ) m / z calc . for c17h14bnclbr [ m ] 357.0091 , found 357.0098 .
obtained as a yellow oil ( 0.6 mmol scale , 142 mg , 67% ) .
h nmr ( 500 mhz , acetone - d6 )  8.45 
 ( s , 1h ) , 7.75 ( d , j = 7.6 hz , 1h ) , 7.637.60 
 ( m , 1h ) , 7.577.53 ( m , 1h ) , 7.397.34 ( m , 1h ) , 7.297.25 
 ( m , 2h ) , 7.026.98 ( m , 2h ) , 5.955.89 ( m , 1h ) , 5.09 
 ( d , j = 10.5 hz , 1h ) , 4.96 ( d , j = 17.4 hz , 1h ) , 4.774.69 ( m , 1h ) , 4.654.58 ( m , 1h ) , 
 3.72 ( s , 3h ) .
c nmr ( 125.8 mhz , acetone - d6 )  160.8 , 145.2 , 140.0 , 135.0 , 132.0 , 129.6 , 129.5 , 
 128.7 , 126.5 , 121.7 , 120.3 , 116.8 , 115.4 , 109.9 , 54.7 , 51.6 .
ir ( neat ) 2948 , 1596 , 1366 , 1235 , 762 cm . hrms ( ci ) m / z calc . for c18h17bbrno [ m ] 353.0587 , found 353.0598 . obtained 
 as a yellow oil ( 0.56 mmol scale , 86 mg , 41% ) .
h nmr ( 500 
 mhz , acetone - d6 )  8.55 
 ( s , 1h ) , 8.02 ( s , 1h ) , 7.947.89 ( m , 3h ) , 7.8 ( dd , j = 7.9 , 1.3 hz , 1h ) , 7.657.57 ( m , 3h ) , 7.537.49 
 ( m , 2h ) , 7.347.30 ( m , 1h ) , 6.045.97 ( m , 1h ) , 5.15 
 ( dd , j = 10.5 , 1.2 hz , 1h ) , 4.94 ( dd , j = 17.4 , 1.2 hz , 1h ) , 4.754.73 ( m , 2h ) .
c nmr 
 ( 125.8 mhz , acetone - d6 )  146.2 , 
 140.0 , 135.1 , 133.2 .
133.0 , 131.3 , 129.7 , 129.1 , 128.9 , 128.0 , 127.6 , 
 126.6 , 126.5 , 125.9 , 125.8 , 122.0 , 117.1 , 115.3 , 51.5 .
ir ( neat ) 3054 , 1545 , 1370 , 1226 , 819 , 764 , 748 cm . hrms ( ci ) m / z calc . for c21h17bbrn [ m ] 373.0637
, found 373.0644 . obtained 
 as an off - white solid ( 1.7 mmol , 210 mg , 37% ) .
h nmr ( 500 mhz , acetone - d6 )  8.46 ( s , 1h ) , 7.767.70 ( m , 1h ) , 7.647.50 
 ( m , 4h ) , 7.377.26 ( m , 2h ) , 6.086.02 ( m , 1h ) , 5.16 
 ( d , j = 10.3 hz , 1h ) , 4.92 ( d , j = 17.4 hz , 1h ) , 4.754.71 ( m , 2h ) .
c nmr ( 125.8 
 mhz , acetone - d6 )  146.0 , 140.2 , 
 135.4 , 131.2 , 129.6 , 129.5 , 129.0 , 126.3 , 124.7 , 121.9 , 117.0 , 115.3 , 
 51.5 .
ir ( neat ) 3066 , 1545 , 1365 , 1237 , 763 , 707 
 cm . hrms ( esi ) m / z calc . for c15h14bbrns [ m + h ] 330.0123 , 
 found 330.0117 .
obtained as an off - white solid ( 0.64 mmol scale , 230 mg , 87% ) . 

h nmr ( 500 mhz , acetone - d6 )  8.57 ( s , 1h ) , 8.158.10 ( m , 
 2h ) , 7.84 ( d , j = 7.8 hz , 1h ) , 7.697.67 ( m , 
 1h ) , 7.627.60 ( m , 1h ) , 7.56 ( d , j = 7.1 hz , 
 1h ) , 7.537.51 ( m , 1h ) , 7.477.43 ( m , 2h ) , 7.387.33 
 ( m , 2h ) , 5.985.90 ( m , 1h ) , 5.06 ( dd , j = 
 10.5 , 1.2 hz , 1h ) , 4.94 ( dd , j = 17.4 , 1.2 hz , 1h ) , 
 4.844.79 ( m , 1h ) , 4.724.68 ( m , 1h ) .
c 
 nmr ( 125.8 mhz , acetone - d6 )  157.5 , 
 156.0 , 146.1 , 140.0 , 134.7 , 130.3 , 129.8 , 129.1 , 127.1 , 126.7 , 124.2 , 
 122.9 , 122.7 , 122.7 , 122.2 , 120.8 , 120.8 , 117.0 , 115.6 , 111.4 , 51.9 .
ir ( neat ) 3055 , 2910 , 1368 , 1187 , 757 cm . hrms ( ci ) m / z calc . for c23h17bbrno [ m ] 413.0587 , found 413.0570 . obtained 
 as an off - white solid ( 1 mmol scale , 242 mg , 71% , ) .
h nmr ( 500 mhz , acetone - d6 )  8.45 ( s , 1h ) , 7.787.71 ( m , 2h ) , 7.647.58 
 ( m , 1h ) , 7.507.35 ( m , 5h ) , 7.337.27 ( m , 1h ) , 4.094.04 
 ( m , 2h ) , 1.721.66 ( m , 2h ) , 1.231.17 ( m , 2h ) , 0.770.73 
 ( m , 3h ) .
c nmr ( 125.8 mhz , acetone - d6 )  145.7 , 139.9 , 131.4 , 129.9 , 129.1 , 127.5 , 127.4 , 
 126.6 , 121.7 , 116.0 , 48.6 , 31.9 , 19.6 , 12.9 .
ir ( neat ) 
 3066 , 3032 , 1596 , 1223 , 765 cm .
hrms ( ci ) m / z calc . for c18h19brbn [ m ] 339.0794 , found 339.0807 .
obtained as an off - white solid ( 3 mmol scale , 371 mg , 37% ) .
h nmr ( 500 mhz , acetone - d6 )  8.45 ( s , 1h ) , 7.87 ( d , j = 8.8 hz , 1h ) , 7.787.75 ( m , 1h ) , 7.657.61 ( m , 1h ) , 
 7.487.30 ( m , 6h ) , 4.05 ( d , j = 6.4 hz , 2h ) , 
 1.241.20 ( m , 1h ) , 0.370.33 ( m , 2h ) , 0.02 - 0.05 ( m , 2h ) .
c nmr ( 125.8 mhz , 
 acetone - d6 )  145.8 , 140.2 , 132.0 , 
 129.8 , 129.1 , 127.6 , 127.4 , 126.6 , 121.8 , 116.6 , 52.4 , 11.0 , 4.0 .
ir ( neat ) 3008 , 1546 , 1363 , 764 , 704 cm . hrms ( ci ) m / z calc . for c18h18bbrn [ m + h ] 338.0716 , found 338.0714 .
obtained 
 as an off - white solid ( 710 mg , 95% , 2 mmol scale ) .
h nmr ( 500 mhz , cdcl3 )  8.38 
 ( s , 1h ) , 7.79 ( s , 1h ) , 7.477.42 ( m , 3h ) , 7.387.35 
 ( m , 3h ) , 7.327.20 ( m , 4h ) , 7.057.02 ( m , 2h ) , 5.32 
 ( s , 2h ) .
c nmr ( 125.8 mhz , cdcl3 )  
 145.1 , 138.9 , 137.8 , 131.5 , 131.4 , 128.8 , 128.2 , 128.1 , 127.6 , 127.1 , 
 125.5 , 123.7 , 119.1 , 114.7 , 53.6 .
ir ( neat ) 3065 , 3029 , 2920 , 1536 , 
 1367 , 1355 , 1242 , 816 cm .
hrms ( ci ) m / z calc . for c21h16bbr2n [ m ] 450.9743 , found 450.9748 . to a biotage microwave vial equipped with a stir bar
was successively 
 introduced sphos - pd - g2 ( 7.2 mg , 10 mol , 2 mol % ) , koh ( 84 mg , 
 1.5 mmol , 3 equiv ) , and 3-bromo-2-aryl-2,1-borazaronaphthalene ( 0.50 
 mmol , 1 equiv ) .
the vial was sealed with a cap lined with a disposable 
 teflon septum , evacuated under vacuum , and purged with ar three times . 

degassed thf ( 0.9 ml ) and degassed h2o ( 0.1 ml ) 
 were added under ar , and the vial was stirred at rt for 18 h. the 
 reaction was diluted with h2o ( 2 ml ) , extracted with etoac 
 ( 3  2 ml ) , and dried ( mgso4 ) .
the solvent was removed in vacuo , and the product was purified by flash column chromatography 
 on florisil using a 0 to 40% ch2cl2/hexane as 
 the eluent to yield the anhydride .
the column was flushed successively 
 with 100% ch2cl2 and 100% etoac to yield the 
 2,1-borazaronaphthol . for reactions that went to completion without 
 side - product formation
, crude reaction mixtures were passed through 
 a plug of florisil to afford the desired product .
characterization 
 of monomer and/or anhydride is provided for each self - arylated product . 
 for those compounds in which complete separation was achieved ,
h nmr ( 500 mhz , 
 acetone - d6 )  7.80 ( s , 1h ) , 7.61 
 ( d , j = 7.8 hz , 1h ) , 7.497.45 ( m , 2h ) , 7.427.33 
 ( m , 4h ) , 7.307.26 ( m , 1h ) , 7.087.04 ( m , 1h ) , 6.64 
 ( br s , 1h ) , 6.076.00 ( m , 1h ) , 5.125.07 ( m , 2h ) , 4.754.70 
 ( m , 2h ) .
c nmr ( 125.8 mhz , acetone - d6 )  143.2 , 142.7 , 141.6 , 135.4 , 130.0 , 128.4 , 128.2 , 
 127.7 , 126.2 , 124.3 , 119.2 , 114.6 , 114.5 , 44.7 .
hrms 
 ( esi ) m / z calc . for c17h17bno [ m + h ] 262.1403 , found 262.1408 .
h nmr ( 500 mhz , 
 acetone - d6 )  7.78 ( s , 1h ) , 7.637.60 
 ( m , 1h ) , 7.497.38 ( m , 6h ) , 7.297.25 ( m , 1h ) , 7.107.05 
 ( m , 1h ) , 6.54 ( s , 1h ) , 4.114.05 ( m , 2h ) , 1.741.70 
 ( m , 2h ) , 1.531.43 ( m , 2h ) , 1.000.93 ( m , 3h ) .
c nmr ( 125.8 mhz , acetone - d6 ) 
  143.0 , 142.9 , 141.6 , 130.3 , 128.5 , 128.4 , 127.8 , 126.2 , 124.4 , 
 119.0 , 113.8 , 42.2 , 31.2 , 20.1 , 13.4 .
ir ( neat ) 3635 , 
 2957 , 2870 , 1387 , 760 cm .
hrms ( ci ) m / z calc . for c18h20bno [ m ] 277.1638 , found 277.1636 .
h 
 nmr ( 500 mhz , acetone - d6 )  7.78 
 ( s , 1h ) , 7.647.55 ( m , 2h ) , 7.487.45 ( m , 3h ) , 7.427.37 
 ( m , 2h ) , 7.307.26 ( m , 1h ) , 7.097.06 ( m , 1h ) , 6.48 
 ( s , 1h ) , 4.023.98 ( m , 2h ) , 1.381.32 ( m , 1h ) , 0.510.45 
 ( m , 4h).c nmr ( 125.8 mhz , acetone - d6 )  143.2 , 142.9 , 141.9 , 130.3 , 128.5 , 
 128.4 , 127.7 , 126.2 , 124.3 , 119.0 , 114.2 , 46.1 , 10.8 , 3.5 .
hrms ( ci ) m / z calc . for c18h18bno [ m ] 275.1481 , found 275.1493 .
h nmr ( 500 mhz , 
 acetone - d6 )  7.86 ( s , 1h ) , 7.63 
 ( d , j = 7.8 hz , 1h ) , 7.55 ( d , j = 
 7.3 hz , 2h ) , 7.447.40 ( m , 2h ) , 7.327.20 ( m , 8h ) , 7.047.01 
 ( m , 1h ) , 6.85 ( s , 1h ) , 5.35 ( s , 2h ) .
c nmr ( 125.8 mhz , 
 acetone - d6 )  143.4 , 142.7 , 141.7 , 
 139.4 , 130.1 , 128.6 , 128.5 , 128.4 , 127.8 , 126.5 , 126.3 , 126.3 , 124.5 , 
 119.4 , 115.0 , 46.3 .
ir ( neat ) 3632 , 3030 , 2924 , 
 1387 , 760 cm .
obtained as a yellow oil ( 0.26 
 mmol scale , 62 
 mg , 87% , 62:38 monomer : anhydride ) .
h nmr ( 500 mhz , acetone - d6 )  7.77 ( s , 1h ) , 7.617.58 ( m , 
 1h ) , 7.417.33 ( m , 4h ) , 7.227.18 ( m , 2h ) , 7.087.03 
 ( m , 1h ) , 6.56 ( s , 1h ) , 6.076.00 ( m , 1h ) , 5.125.06 
 ( m , 2h ) , 4.724.70 ( m , 2h ) , 2.35 ( s , 3h ) .
c nmr 
 ( 125.8 mhz , acetone - d6 )  142.8 , 
 141.5 , 139.8 , 135.6 , 135.4 , 129.9 , 129.1 , 128.0 , 127.6 , 124.3 , 119.1 , 
 114.6 , 114.5 , 44.7 , 20.1 .
ir ( neat ) 3607 , 3062 , 2979 , 
 1384 , 1353 , 750 cm .
hrms ( ci ) m / z calc . for c18h18bno [ m ] 275.1481 , found 275.1477 .
obtained as a yellow oil ( 0.26 
 mmol scale , 62 mg , 87% , 62:38 monomer : anhydride ) .
h nmr 
 ( 500 mhz , acetone - d6 )  7.67 ( s , 
 2h ) , 7.58 ( d , j = 7.6 hz , 2h ) , 7.407.36 ( m , 
 4h ) , 7.107.05 ( m , 6h ) , 6.89 ( d , j = 7.8 hz , 
 4h ) , 6.055.97 ( m , 2h ) , 5.13 ( dd , j = 10.4 , 
 1.3 hz , 2h ) , 5.04 ( dd , j = 17.5 , 1.3 hz , 2h ) , 4.724.69 
 ( m , 4h ) , 2.12 ( s , 6h ) .
c nmr ( 125.8 mhz , acetone - d6 )  142.8 , 141.1 , 139.2 , 135.2 , 135.0 , 
 129.8 , 128.2 , 127.9 , 127.9 , 124.7 , 119.6 , 115.0 , 114.9 , 45.6 , 20.0 .
hrms ( esi ) m / z calc . for c18h18bno [ m  c18h16bno ] 275.1481 , found 275.1478 .
hrms found for [ monomer ] . obtained as a yellow oil ( 0.5 mmol 
 scale , 98 mg , 
 71% , 77:23 monomer :
h nmr ( 500 mhz , acetone - d6 )  7.78 ( s , 1h ) , 7.61 ( d , j = 7.6 hz , 1h ) , 7.417.34 ( m , 2h ) , 7.297.25 ( m , 3h ) , 
 7.117.04 ( m , 2h ) , 6.61 ( s , 1h ) , 6.076.01 ( m , 1h ) , 
 5.125.07 ( m , 2h ) , 4.724.70 ( m , 2h ) , 2.36 ( s , 3h ) .
c nmr ( 125.8 mhz , acetone - d6 ) 
  143.0 , 142.6 , 141.6 , 137.8 , 135.4 , 130.5 , 130.0 , 128.4 , 128.1 , 
 127.0 , 124.7 , 124.3 , 119.1 , 114.6 , 114.5 , 44.7 , 20.6 .
ir ( neat ) 3623 , 2977 , 2922 , 1608 , 1383 , 761 cm .
hrms ( esi ) m / z calc . for c18h17bno [ m  h ] 274.1403 , found 
 274.1404 .
obtained as a yellow oil ( 0.5 
 mmol scale , 98 mg , 71% , 77:23 monomer : anhydride ) .
h nmr 
 ( 500 mhz , acetone - d6 )  7.61 ( s , 
 2h ) , 7.56 ( d , j = 7.6 hz , 2h ) , 7.407.36 ( m , 
 4h ) , 7.08 ( d , j = 5.9 hz , 2h ) , 6.946.88 ( m , 
 6h ) , 6.79 ( d , j = 6.8 hz , 2h ) , 6.116.06 ( m , 
 2h ) , 5.185.12 ( m , 4h ) , 4.874.83 ( m , 2h ) , 4.754.72 
 ( m , 2h ) , 2.04 ( s , 6h ) . c nmr ( 125.8 mhz , acetone - d6 )  142.9 , 141.8 , 141.2 , 136.8 , 135.2 , 
 129.9 , 128.7 , 128.1 , 127.4 , 126.5 , 125.2 , 124.6 , 119.6 , 115.1 , 114.9 , 
 45.7 , 20.3 .
ir ( neat ) 3034 , 2982 , 1605 , 1384 , 1352 , 
 760 cm .
hrms ( esi ) m / z calc . for c18h17bno [ m  
 c18h17bno ] 274.1403 , found 274.1410 . 

hrms found for [ monomer - h ] . obtained as a yellow oil ( 0.45 
 mmol scale , 76 mg , 59% , > 95:5 monomer : anhydride).h nmr ( 500 mhz , acetone - d6 ) 
  7.66 ( s , 2h ) , 7.58 ( d , j = 7.3 hz , 2h ) , 7.477.39 
 ( m , 4h ) , 7.127.08 ( m , 2h ) , 7.056.97 ( m , 8h ) , 6.176.10 
 ( m , 2h ) , 5.215.12 ( m , 4h ) , 4.874.79 ( m , 4h ) .
c nmr ( 125.8 mhz , acetone - d6 ) 
  147.9 , 141.4 , 136.4 , 134.8 , 132.6 , 131.4 , 131.3 , 131.2 , 130.1 , 
 130.7 , 129.4 , 128.0 , 123.6 , 118.6 , 117.0 , 51.5 .
ir ( neat ) 3063 , 2974 , 1384 , 1352 , 1187 , 749 cm .
hrms ( esi ) m / z calc . for c31h24b2cl2n2o [ m 
  c3h4 ] 532.1452 , found 532.1424 . 

hrms found for [ m - allyl ] . obtained as an off - white solid 
 ( 0.31 mmol scale , 71 mg , 82% , > 95:5 monomer : anhydride ) .
h nmr ( 500 mhz , acetone - d6 )  7.66 ( s , 2h ) , 7.58 ( d , j = 7.8 
 hz , 2h ) , 7.437.39 ( m , 4h ) , 7.177.08 ( m , 6h ) , 6.846.80 
 ( m , 4h ) , 6.136.04 ( m , 2h ) , 5.18 ( d , j = 10.5 
 hz , 2h ) , 5.07 ( d , j = 17.1 hz , 2h ) , 4.794.77 
 ( m , 4h ) .
c nmr ( 125.8 mhz , acetone - d6 )  161.4 ( d , j = 243 hz ) , 143.4 , 
 141.1 , 138.2 ( d , j = 3.9 hz ) , 135.0 , 130.0 , 129.7 , 
 129.7 , 128.3 , 124.4 , 119.8 , 115.0 ( d , j = 5.0 hz ) , 
 114.2 ( d , j = 22 hz ) , 45.6 .
ir ( neat ) 
 3063 , 2926 , 1384 , 1352 , 749 cm .
hrms ( ci ) m / z calc . for c17h15bnof [ m  c17h13bnof ]
hrms found for [ monomer ] . obtained as an off - white 
 solid ( 0.5 mmol scale , 110 mg , 67% , > 95:5 monomer : anhydride ) .
h nmr ( 500 mhz , acetone - d6 )  7.78 ( s , 2h ) , 7.6 ( d , j = 7.3 hz , 2h ) , 7.487.37 ( m , 8h ) , 7.28 ( d , j = 7.6 hz , 4h ) , 7.137.08 ( m , 2h ) , 6.156.10 ( m , 2h ) , 
 5.20 ( d , j = 10.5 hz , 2h ) , 5.09 ( d , j = 17.1 hz , 2h ) , 4.834.81 ( m , 4h ) .
c nmr ( 125.8 
 mhz , acetone - d6 )  146.0 , 144.5 , 
 141.3 , 134.9 , 130.4 , 128.9 , 128.5 , 127.5 , 126.7 ( q , j = 264 hz ) , 124.4 ( q , j = 5.0 hz ) , 124.2 , 120.0 , 
 115.2 , 115.1 , 45.6 .
ir ( neat ) 3056 , 3 + 36 , 2384 , 
 1324 , 1110 , 761 cm .
hrms ( ci ) m / z calc . for c18h15bf3no [ m  c18h13bf3no ] 329.1199
hrms found for [ monomer ] . obtained as a yellow oil ( 0.36 mmol scale , 94 
 mg , 90% , 15:85 monomer : anhydride ) .
h nmr ( 500 mhz , acetone - d6 )  7.70 ( s , 1h ) , 7.58 ( d , j = 7.6 hz , 1h ) , 7.407.34 ( m , 2h ) , 7.307.25 ( m , 2h ) , 
 7.056.99 ( m , 3h ) , 6.34 ( s , 1h ) , 6.045.98 ( m , 1h ) , 
 5.10 ( dd , j = 13.7 , 1.7 hz , 2h ) , 4.724.70 
 ( m , 2h ) , 3.83 ( s , 3h ) .
c nmr ( 125.8 mhz , acetone - d6 )  156.4 , 143.8 , 141.7 , 135.6 , 132.0 , 
 129.9 , 129.9 , 128.0 , 128.0 , 124.3 , 120.9 , 118.9 , 114.5 , 114.0 , 110.9 , 
 54.9 , 44.6 .
ir ( neat ) 3628 , 2980 , 1386 , 1352 , 1187 , 
 750 cm .
obtained as an off - white 
 solid ( 0.20 
 mmol scale , 35 mg , 56% , > 95:5 monomer : anhydride ) .
h nmr ( 500 mhz , acetone - d6 )  7.68 ( d , j = 6.4 hz , 2h ) , 7.59 
 ( s , 2h ) , 7.557.52 ( m , 4h ) , 7.487.37 ( m , 8h ) , 7.347.30 
 ( m , 4h ) , 7.23 ( d , j = 8.3 hz , 2h ) , 7.067.01 
 ( m , 2h ) , 6.196.11 ( m , 2h ) , 5.225.14 ( m , 4h ) , 4.934.83 
 ( m , 4h ) . c nmr ( 125.8 mhz , acetone - d6 )  143.6 , 141.2 , 139.5 , 135.2 , 133.3 , 132.0 , 130.0 , 
 128.2 , 127.6 , 127.2 , 126.9 , 126.8 , 126.3 , 125.4 , 125.1 , 124.5 , 119.6 , 
 115.2 , 115.0 , 45.7 .
ir ( neat ) 3057 , 2923 , 1390 , 
 1354 , 1215 , 742 cm .
hrms ( ci ) m / z calc . for c21h18bno [ m 
  c21h16bno ] 311.1481 , found 
 311.1472 .
hrms found for [ monomer ] . obtained as a yellow oil ( 0.5 mmol 
 scale , 114 mg , 85% , 60:40 monomer :
h nmr ( 500 
 mhz , acetone - d6 )  
 7.99 ( s , 1h ) , 7.637.58 ( m , 2h ) , 7.497.46 ( m , 1h ) , 
 7.457.42 ( m , 1h ) , 7.397.32 ( m , 2h ) , 7.087.04 
 ( m , 1h ) , 6.70 ( s , 1h ) , 6.075.97 ( m , 1h ) , 5.115.04 
 ( m , 2h ) , 4.724.70 ( m , 2h ) .
c nmr ( 125.8 mhz , 
 acetone - d6 )  142.1 , 141.9 , 141.4 , 
 135.2 , 129.9 , 128.0 , 127.2 , 125.3 , 124.3 , 121.1 , 119.3 , 114.6 , 114.4 , 
 44.8 .
ir ( neat ) 3627 , 3064 , 2932 , 1385 , 1352 , 1187 , 
 750 cm .
hrms ( esi ) m / z calc . for c15h15bnos [ m + h ] 268.0967
obtained as a yellow oil ( 0.5 mmol 
 scale , 111 
 mg , 63% , 36:64 monomer : anhydride ) .
h nmr ( 500 mhz , acetone - d6 )  8.138.10 ( m , 1h ) , 8.06 ( s , 
 1h ) , 8.048.00 ( m , 1h ) , 7.717.67 ( m , 1h ) , 7.667.62 
 ( m , 1h ) , 7.567.39 ( m , 6h ) , 7.157.11 ( m , 1h ) , 7.02 
 ( m , 1h ) , 6.146.02 ( m , 1h ) , 5.225.15 ( m , 2h ) , 4.844.82 
 ( m , 2h ) .
c nmr ( 125.8 mhz , acetone - d6 )  157.0 , 154.6 , 146.3 , 143.1 , 136.6 , 131.3 , 129.7 , 
 128.5 , 128.5 , 128.2 , 125.4 , 125.2 , 125.0 , 124.4 , 123.8 , 121.8 , 120.2 , 
 120.0 , 115.8 , 115.8 , 112.7 , 45.9 .
ir ( neat ) 3623 , 
 3063 , 2928 , 1385 , 1187 , 750 cm .
hrms ( esi ) m / z calc . for c23h19bno2 [ m + h ] 352.1509 , found 352.1523 . to a biotage microwave vial equipped with stir bar 

was successively introduced koh ( 0.3 mmol , 3 equiv ) and bis(1-allyl-3-(3-methylphenyl)-2,1-borazaro-2-naphthyl ) 
 ether ( 0.1 mmol , 1 equiv ) .
the vial was sealed with a cap lined with 
 a disposable teflon septum , evacuated under vacuum , and purged with 
 ar three times .
degassed thf ( 0.9 ml ) and degassed h2o ( 0.1 ml ) were added under ar , and the vial was stirred at rt for 
 18 h. the reaction was diluted with h2o ( 1 ml ) , extracted 
 with etoac ( 3  1 ml ) , and dried ( mgso4 ) .
the solvent 
 was removed in vacuo to yield 1-allyl-3-(3-methylphenyl)-2,1-borazaronaphthol 
 ( 3b - monomer ) . to a biotage microwave vial equipped with a stir bar
was successively 
 introduced t - bu3p - pd - g2 ( 2.3 mg , 5 mol , 
 2 mol % ) , cs2co3 ( 84 mg , 1.5 mmol , 3 equiv ) , 
 phenylboronic acid ( 31 mg , 1.0 equiv ) and 1-benzyl-3,6-dibromo-2-phenyl-2,1-borazaronaphthalene 
 ( 0.25 mmol , 1 equiv ) . the vial was sealed with a cap lined with a 
 disposable teflon septum , evacuated under vacuum , and purged with 
 ar three times .
anhydr degassed thf ( 0.6 ml ) and degassed h2o ( 0.6 ml ) were added under ar , and the vial was stirred at rt for 
 18 h. the reaction was diluted with h2o ( 2 ml ) , extracted 
 with etoac ( 3  2 ml ) , and dried ( mgso4 ) .
the solvent 
 was removed in vacuo , and the product was purified 
 by passing through a short plug of florisil . obtained as an off - white solid ( 89 mg , 92% ) . 

h nmr ( 500 mhz , acetone - d6 )  
 7.987.94 ( m , 2h ) , 7.67 ( d , j = 7.3 hz , 2h ) , 
 7.617.55 ( m , 3h ) , 7.457.40 ( m , 4h ) , 7.357.27 
 ( m , 7h ) , 7.247.20 ( m , 1h ) , 6.97 ( br s , 1h ) , 5.38 ( s , 2h ) .
c nmr ( 125.8 mhz , acetone - d6 ) 
  143.9 , 142.9 , 141.4 , 140.7 , 139.6 , 132.3 , 128.9 , 128.7 , 128.6 , 
 128.3 , 128.0 , 127.0 , 126.8 , 126.7 , 126.6 , 126.6 , 126.6 , 125.0 , 115.8 , 
 45.6 b nmr ( 128.38 mhz , acetone - d6 )  29.8 .
ir ( neat ) 3602 , 3026 , 1387 , 763 , 698 cm . hrms ( esi ) m / z calc . for c27h23bno [ m + h ]
equipped with a stir bar was successively 
 introduced t - bu3p - pd - g2 ( 1.7 mg , 3.3 mol , 
 1 mol % ) , and 3-bromo-2-aryl-2,1-borazaronaphthalene ( 0.33 mmol , 1 
 equiv ) .
the vial was sealed with a cap lined with a disposable teflon 
 septum , evacuated under vacuum , and purged with ar three times .
degassed thf ( 0.8 ml ) was added under ar , and the vial was cooled 
 to 0 c .
phmgbr ( 1 m in thf , 0.4 ml diluted to 0.8 ml ) was added 
 dropwise over 15 min at 0 c .
aq nh4cl ( 0.5 ml ) , extracted with etoac ( 3  2 ml ) , and dried ( mgso4 ) .
the solvent was removed in vacuo , and 
 the product was purified by flash column chromatography on silica 
 gel using a 0 to 20% ch2cl2/hexane as the eluent . obtained as a yellow oil ( 89 mg , 84% ) .
h nmr 
 ( 500 mhz , acetone - d6 )  8.09 ( s , 
 1h ) , 7.85 ( d , j = 7.8 hz , 1h ) , 7.667.62 ( m , 
 1h ) , 7.577.52 ( m , 1h ) , 7.337.23 ( m , 6h ) , 7.147.05 
 ( m , 5h ) , 6.086.01 ( m , 1h ) , 5.15 ( d , j = 10.5 
 hz , 1h ) , 4.98 ( d , j = 17.4 hz , 1h ) , 4.764.74 
 ( m , 2h ) .
c nmr ( 125.8 mhz , acetone - d6 )  144.4 , 143.0 , 140.3 , 135.7 , 131.7 , 130.4 , 128.6 , 
 128.5 , 127.4 , 127.2 , 127.0 , 126.6 , 125.4 , 121.3 , 116.6 , 115.0 , 50.1 .
hrms ( ci ) m / z calc . for c23h20bn [ m ] 321.1689 , found 321.1684 . obtained as a yellow oil ( 101 mg , 89% ) .
h nmr ( 500 mhz , acetone - d6 )  
 8.08 ( s , 1h ) , 7.84 ( d , j = 7.6 hz , 1h ) , 7.657.62 
 ( m , 1h ) , 7.577.52 ( m , 1h ) , 7.337.25 ( m , 6h ) , 7.157.10 
 ( m , 2h ) , 6.916.85 ( m , 2h ) , 6.076.01 ( m , 1h ) , 5.15 
 ( d , j = 10.5 hz , 1h ) , 4.97 ( d , j = 17.2 hz , 1h ) , 4.744.72 ( m , 2h ) .
c nmr ( 125.8 
 mhz , acetone - d6 )  161.5 ( d , j = 243 hz ) , 143.3 , 140.9 ( d , j = 4 hz ) , 
 140.6 , 135.9 , 132.0 , 130.7 , 130.5 ( d , j = 8 hz ) , 
 128.8 , 127.5 ( d , j = 20 hz ) , 126.7 , 121.7 , 116.9 , 
 115.3 , 114.4 , 114.3 , 51.0 .
ir ( neat ) 3068 , 1506 , 1370 , 
 1220 , 832 , 766 cm . hrms ( ci ) m / z calc . for c23h19bfn [ m ] 339.1595 , found 339.1604 .
h nmr ( 500 mhz , acetone - d6 )  7.91 ( s , 1h ) , 7.78 ( d , j = 7.9 hz , 1h ) , 7.63 ( d , j = 8.5 hz , 1h ) , 7.547.50 
 ( m , 1h ) , 7.297.25 ( m , 3h ) , 7.167.12 ( m , 4h ) , 7.107.06 
 ( m , 1h ) , 6.866.83 ( m , 1h ) , 6.65 ( d , j = 8.2 
 hz , 1h ) , 6.106.03 ( m , 1h ) , 5.17 ( dd , j = 
 10.5 , 1.4 hz , 1h ) , 5.01 ( dd , j = 17.1 , 1.5 hz , 1h ) , 
 4.764.74 ( m , 2h ) , 3.33 ( s , 3h ) .
c nmr ( 125.8 
 mhz , acetone - d6 )  156.3 , 142.9 , 
 140.5 , 136.2 , 134.4 , 131.8 , 130.3 , 129.7 , 128.3 , 127.6 , 127.0 , 126.9 , 
 126.7 , 121.3 , 120.2 , 116.8 , 115.2 , 110.2 , 54.3 , 50.9 .
ir ( neat ) 3006 , 2830 , 1489 , 1370 , 1340 , 748 cm .
hrms ( ci ) m / z calc . for c24h22bno [ m ] 351.1794 , found 351.1800 .
h nmr ( 500 mhz , acetone - d6 )  8.08 ( s , 1h ) , 7.83 ( d , j = 7.6 hz , 1h ) , 7.63 ( d , j = 8.6 hz , 1h ) , 7.557.51 
 ( m , 1h ) , 7.347.25 ( m , 6h ) , 7.00 ( d , j = 6.6 
 hz , 1h ) , 6.936.89 ( m , 1h ) , 6.816.77 ( m , 1h ) , 6.076.01 
 ( m , 1h ) , 5.15 ( d , j = 10.5 hz , 1h ) , 4.97 ( d , j = 17.4 hz , 1h ) , 4.754.73 ( m , 2h ) , 2.09 ( s , 3h ) .
c nmr ( 125.8 mhz , acetone - d6 ) 
  159.7 ( d , j = 243 hz ) , 142.8 , 140.3 , 135.7 , 
 131.8 ( d , j = 5 hz ) , 131.7 , 130.4 , 128.5 , 127.7 ( d , j = 6 hz ) , 127.3 , 127.1 , 126.5 , 123.3 , 123.1 , 121.4 , 116.6 , 
 115.1 , 113.7 ( d , j = 22 hz ) , 50.1 , 13.5 .
ir ( neat ) 3046 , 1498 , 1367 , 1223 , 1118 , 766 , 704 cm . hrms ( ci ) m / z calc . for c24h21bfn [ m ] 353.1751 , found 353.1761 .
h nmr ( 500 mhz , acetone - d6 )  8.16 ( s , 1h ) , 7.86 ( d , j = 7.6 
 hz , 1h ) , 7.64 ( d , j = 7.3 hz , 1h ) , 7.477.43 
 ( m , 2h ) , 7.397.35 ( m , 1h ) , 7.317.25 ( m , 5h ) , 7.217.11 
 ( m , 9h ) , 5.42 ( s , 2h ) .
c nmr ( 125.8 mhz , acetone - d6 )  144.4 , 143.4 , 140.3 , 139.1 , 131.2 , 
 130.5 , 128.8 , 128.7 , 128.5 , 128.5 , 127.5 , 127.3 , 126.8 , 126.7 , 125.6 , 
 125.5 , 121.5 , 117.1 , 52.3 .
ir ( neat ) 3064 , 2922 , 1547 , 
 1376 , 767 , 702 cm . hrms ( ci ) m / z calc . for c27h22bn [ m ] 371.1845 , found 371.1840 .
the 
 geometries were optimized at the b3lyp/6 - 311(d , p ) level , and molecular 
 orbitals and molecular energies were calculated at the same level .
 unlike 
 their b - alkyl counterparts , brominated n - alkyl b - aryl 2,1-borazaronaphthalenes 
 undergo a self - arylation reaction in the presence of a catalytic amount 
 of palladium and base , in which the azaborine serves as both the electrophile 
 and the nucleophile . 
 the products of the self - arylation are air- and 
 moisture - stable 2,1-borazaronaphthols , previously only observed in 
 basic alcoholic solvents . 
 the steric encumbrance of the azaborine 
 appears to prevent formation of the corresponding boron acid anhydride , 
 allowing access to a family of 2,1-borazaronaphthol derivatives . 
Introduction
Results and Discussion
Conclusions
Experimental Section