n bond in 
 an aromatic system results in azaborines , heterocycles that retain 
 most of the aromatic character and thermal stability associated with 
 their c = c analogues .
n bond desymmetrizes the heterocycle , allowing functionalization 
 at various positions around the ring with complete regiochemical control . 

this permits access to elaborate azaborines , the corresponding carbon 
 analogues of which can not easily be prepared .
n bonds 
 are isoelectronic with c = c double bonds , azaborines have been 
 examined as isosteres for all - carbon aromatics in medicinal chemistry .
azaborines have demonstrated antifungal activity 
 against several different fungi in addition 
 to exhibiting antibacterial activity against gram - negative bacteria .
furthermore , the azaborine derivatives of ethylbenzene can bind 
 the hydrophobic pocket of the l99a mutant of the t4 lysozyme as well 
 as inhibit the ethylbenzene dehydrogenase ( ebdh ) enzyme .
therefore , the synthesis of complex azaborines can provide access 
 to novel drug candidates , thereby aiding the exploration of novel 
 chemical space . additionally , the 
 replacement of a c = c bond with a b 
thus , in addition to their applications in medicinal 
 chemistry , the isosteric replacement of c = c with b 
n 
 has led to the synthesis of classes of compounds that serve as organic 
 light - emitting diodes ( oleds ) and organic 
 field - effect transistors ( ofets ) .
consequently , 
 functionalization of azaborine cores is anticipated to provide access 
 to new classes of compounds with potentially different and impactful 
 photophysical properties .
the promise of azaborines in these 
 fields led us to develop a method 
 to synthesize the core of 2,1-borazaronaphthalene , the b 
n 
 analogue of naphthalene ( eq 1 ) . 2,1-borazaronaphthalenes synthesized through this route 
 are stable toward both strong acid ( ph 2 at 37 c ) and base ( cs2co3/h2o at 60 c ) , thus demonstrating 
 their aromatic nature .
however , the synthesis of an azaborine core 
 is only the starting point because further functionalization of these 
 molecules allows facile access to novel , increasingly complex molecules.1 the method developed for accessing the core of 2,1-borazaronaphthalenes 
 permitted the synthesis of a library of over 50 compounds with various 
 substitutions .
this convergent , modular 
 route utilized simple starting materials under mild reaction conditions 
 to afford a highly functionalized azaborine core , allowing selective 
 substitution around the 2,1-borazaronaphthalene system by starting 
 from an n- or aryl - substituted 2-aminostyrene to 
 synthesize 1- , 2- , 5- , 6- , 7- , or 8-substituted 2,1-borazaronaphthalenes . 
 however , it was not possible to access 3-substituted-2,1-borazaronaphthalenes 
 through this method , as the reaction between potassium phenyltrifluoroborate 
 and ( e)-2-styrylaniline did not provide any of the 
 desired product ( eq 2).2 an alternative method was therefore required for substitution 
 at 
 the 3-position of these azaborines , and thus , a different retrosynthetic 
 disconnection was envisioned ( scheme 1 ) . a 
 suzuki  miyaura cross - coupling between 
 brominated 2,1-borazaronaphthalenes and potassium ( hetero)aryltrifluoroborates was proposed to elaborate the 2,1-borazaronaphthalenes . 

through such a protocol , a library of ( hetero)arylated azaborines 
 could be synthesized easily from a brominated starting material , thereby 
 building substantial molecular complexity over two short steps .
only 
 two isolated examples of the cross - coupling of halogenated azaborines 
 and aryl nucleophiles have been previously reported .
boronic acids and many boronic 
 acid surrogates are capable of undergoing 
 transmetalation in cross - coupling reactions because an activated palladium 
 complex interacts with a vacant orbital on the boron . because of the b 
n bond , the empty p orbital on 
 boron within the azaborine is occupied by electron donation from the 
 nitrogen .
this feature contributes to the azaborine s aromatic 
 stability but was anticipated to reduce its ability to participate 
 in transmetalation .
therefore , we expected selectivity in transmetalation 
 such that the cross - coupling would proceed with the external organoboron 
 nucleophile , leaving the b  c bond of the azaborine intact . reported herein is the cross - coupling of 3-bromo-2,1-borazaronaphthalenes 
 with an array of potassium ( hetero)aryltrifluoroborates , providing 
 access to 3-(hetero)aryl-2,1-borazaronaphthalenes .
this cross - coupling 
 represents the first reported cross - coupling between an electrophilic 
 brominated azaborine and a nucleophilic organometallic reagent . in 
 this work ,
26 2,1-borazaronaphthalenes with various substitutions 
 on boron and nitrogen were brominated , and 43 different cross - coupled 
 2,1-borazaronaphthalenes were obtained utilizing a palladium - catalyzed 
 suzuki  miyaura cross - coupling reaction .
the method was then 
 extended to show a second site - selective bromination and subsequent 
 cross - coupling to access diarylated products .
the methods developed 
 herein demonstrate that the unique site - selective emplacement of groups 
 about the azaborine core allows more diverse and precise elaboration 
 of these systems with far greater ease and higher selectivities than 
 with naphthalene itself .
2,1-borazaronaphthalenes 
 exhibit reactivity toward electrophilic 
 aromatic substitution that is complementary to that of their c = c 
 counterparts because the b 
n bond desymmetrizes the molecule , 
 with different positions being activated relative to those in naphthalene . 

because azaborines are generally less aromatic than their c = c 
 analogues , 2,1-borazaronaphthalenes are 
 also activated toward electrophilic aromatic substitution , and in 
 general such reactions take place under milder reaction conditions . 

therefore , initial efforts were focused on the bromination of 2,1-borazaronaphthalenes 
 through an electrophilic aromatic substitution to generate the required 
 electrophilic partner .
the bromination and chlorination of 2-methyl-2,1-borazaronaphthalene 
 ( 1 ) were first reported by dewar in 1961 ( eq 3 ) . to this day , these 
 two halogenated 2,1-borazaronaphthalenes remain the only 3-substituted-2,1-borazaronaphthalenes 
 reported in the literature .
the addition of bromine to a solution 
 of 1 in acetic acid resulted in a 60% isolated yield 
 of the desired product . a major halogenated
, deboronated side product 
 was generated in 29% yield as a result of the harsh reaction conditions . 

n 
 isostere of benzene , was reported to provide the desired product in 
 91% yield under milder reaction conditions . utilizing these modified conditions for the bromination of 2,1-borazaronaphthalene 
 by changing the solvent from acetic acid to dichloromethane and cooling 
 the reaction to 0 c enabled the desired 3-bromo-2,1-borazaronaphthalenes 
 to be easily synthesized .
the rate of addition of bromine was vital 
 to the success of the reaction : a rate of 1 mmol / h resulted 
 in a high yield for many 2,1-borazaronaphthalenes , while more rapid 
 addition of bromine caused the reaction to exotherm , resulting in 
 decomposition of the 2,1-borazaronaphthalene .
brominations could also 
 be carried out in a shorter period of time by conducting the reaction 
 at 78 c.3 the bromination conditions were applied 
 to an array of 2,1-borazaronaphthalenes 
 to access 3-bromo-2,1-borazaronaphthalenes in high yield ( table 1 ) .
free n - h 2,1-borazaronaphthalenes 
 with alkyl substituents on boron were brominated in yields of up to 
 99% ( entries 15 ) .
bromination of 2-aryl-2,1-borazaronaphthalenes 
 with either electron - withdrawing or electron - donating groups on the 
 arene afforded the desired products in yields of 8199% ( entries 
 810 , 1317 , and 19 ) .
brominated heteroaryl - containing 
 2,1-borazaronaphthalenes were obtained in variable yields ( entries 
 11 , 12 , and 18 ) .
substitution on nitrogen did not interfere with the 
 bromination , and the desired products were obtained in modest to excellent 
 yields ( entries 6 , 7 , and 1319 ) .
the brominated products 2r and 2 t were synthesized in lower yield as 
 a result of the formation of side products resulting from multiple 
 additions of bromine .
interestingly , good to excellent yields of the 
 brominated borazines were achieved even in the presence of what might 
 be considered to be activated arenes ( entries 9 , 12 , 14 , and 19 ) . 

the extraordinary reactivity of the 2,1-borazaronaphthalene toward 
 electrophilic aromatic substitution was further demonstrated in the 
 cases of substrates 2 g , 2 m , 2n , and 2 t , where the azaborine core was brominated in 
 preference to either an allyl group on 
 nitrogen or an alkyne on boron ( entries 
 7 , 13 , 14 , 20 ) . reaction conditions ( unless otherwise 
 noted ) : 1.0 
 equiv of 2,1-borazaronaphthalene , 1.1 equiv of br2 , ch2cl2 , 0 c to rt .
attempts 
 to synthesize 2,1-borazaronaphthalenes from electron - poor 
 2-aminostyrenes ( i.e. , 2-amino-5-trifluoromethylstyrene ) were unsuccessful 
 under our developed conditions . however , n - substituted 
 2-aminostyrenes are suitable substrates for the synthesis of azaborines . 

substitution of the all - carbon ring of the 2,1-borazaronaphthalene does not affect 
 the bromination because the corresponding products were isolated in 
 good yields ( entries 21 and 22 ) .
the desired 3-bromo-2,1-borazaronaphthalenes 
 were synthesized with 
 aryl , heteroaryl , alkynyl , and alkyl substituents on boron . however , 
 the presence of an alkene on boron resulted in dibromination of the 
 alkene as the major product ( eq 4 ) .
the same 
 result was evident in the bromination of an alkenyl - substituted arene , 
 where addition of bromine resulted in dibromination of the alkene 
 followed by bromination of the arene.4 the addition of a second equivalent 
 of bromine to the 2,1-borazaronaphthalene 
 resulted in site - selective dibromination at the 3- and 6-positions 
 of the 2,1-borazaronaphthalene ( eq 5 ) , providing 
 the desired product in excellent yield and again demonstrating extraordinary 
 complementarity to naphthalene systems in terms of both selectivity 
 and structural diversity.5 as noted previously , the isosteric 
 replacement of c = c with 
 b 
n effectively desymmetrizes the molecule and selectively 
 activates the system for electrophilic aromatic substitution to such 
 an extent that both the mono- and dibromination reactions proceed 
 with complete regiochemical control .
resonance structures can be used 
 to rationalize activation of c3 and c6 , but such an analysis indicates 
 that c8 should also be activated ( scheme 2 ) .
this observed selectivity of electrophilic aromatic substitution 
 at c3 and c6 was reinforced and refined by a rudimentary dft calculation analyzing the homo of the 2,1-borazaronaphthalene . 

this calculation , completed at the b3lyp/6 - 31g(d ) level of theory , 
 detailed the electron density of the homo of 2,1-borazaronaphthalene 
 ( figure 1 ) .
the increased electron density 
 at the fused carbons ( c4a and c8a ) suggests that c4a should be nucleophilic . 

however , addition of an electrophile at c4a would break the aromaticity 
 in both rings of the azaborine , resulting in a higher energy barrier 
 for reaction , thereby disfavoring addition at this carbon .
the carbon 
 with the highest electron density in the homo is c3 , with an electron 
 density of 0.342 , whereas c6 is a close second with an electron density 
 of 0.325 .
the electron density of c8 is only 0.024 , showing the lack 
 of nucleophilicity of this carbon relative to c3 and c6 .
similar calculations 
 for substrates with substitution around the azaborine ( i.e. , 2u and 2v ) show a similar trend , confirming the 
 high reactivity at the 3-position .
dft - calculated homo of 2,1-borazaronaphthalene 
 [ calculated at the 
 b3lyp/6 - 31g(d ) level of theory ] .
computational studies of brominated intermediates are equally 
 informative 
 in rationalizing the site selectivity observed .
a series of calculations at the b3lyp/6 - 31g(d ) level of 
 theory evaluated the relative energies of the intermediates formed 
 after addition of bromine to 2-methyl-2,1-borazaronaphthalene 1 ( figure 2 ) .
the relative energy of 
 the intermediate for the bromination at c3 is much lower than those 
 at c6 and c8 , explaining the first bromination at the 3-position . 

n 
 ring because it is both less aromatic and less thermally stable than 
 a c = c ring , which in turn increases its reactivity .
addition of a second equivalent of bromine results 
 in addition to the c = c ring of the 2,1-borazaronaphthalene , 
 specifically at the 6-position , because the intermediate derived from 
 addition at that site is 2 kcal / mol lower in energy than that 
 of the c8-brominated intermediate .
relative energies for the addition of 
 bromine to 2-methyl-2,1-borazaronaphthalene 
 intermediates [ calculated at the b3lyp/6 - 31g(d ) level of theory ] . the impact of the site - selective 
 bromination can be demonstrated 
 by comparison with the bromination of naphthalene .
unlike 2,1-borazaronaphthalenes , 
 which undergo electrophilic aromatic substitution selectively at the 
 3-position , the natural site for electrophilic aromatic substitution 
 of naphthalene is the 1-position . in 
 fact , the bromination of 2-methylnaphthalene to form 1-bromo-2-methylnaphthalene 
 proceeds in 87% yield whereas the bromination 
 of the corresponding azaborine 1 yields 3-bromo-2-methyl-2,1-borazaronaphthalene 
 ( 2a ) in 99% yield , demonstrating complementary electrophilic 
 aromatic substitutions of the c = c and b 
n analogues 
 to access molecules with different substitution patterns . furthermore , 
 to install a halogen at the 3-position of naphthalene 

requires either a directing group under harsh reaction conditions or a gold - catalyzed cyclization in the presence 
 of nis .
the corresponding bromination 
 of 2,1-borazaronaphthalene is a one - step process resulting in the 
 addition of bromine to a highly functionalized molecule . upon 
 the synthesis of the brominated 2,1-borazaronaphthalenes , 
 investigations of the suzuki 
3-bromo-2-methyl-2,1-borazaronaphthalene 2a and potassium phenyltrifluoroborate were chosen as model substrates 
 in the reaction to synthesize 2-methyl-3-phenyl-2,1-borazaronaphthalene 
 ( 3a ) ( eq 6).6 initially , stability tests were performed to ensure that 2,1-borazaronaphthalenes 
 would be stable in basic media at the elevated temperatures required 
 for the cross - coupling .
heating of the 2,1-borazaronaphthalenes at 
 60 c in a 1:1 thf / h2o solvent system with 3 equiv 
 of cs2co3 resulted in complete recovery of the 
 2,1-borazaronaphthalenes .
initial reaction conditions for the cross - coupling 
 of phenyltrifluoroborate with the brominated azaborine 2a were determined through a limited screening process . of the palladium 
 sources and ligands tested in this initial screen , the ( t - bu3p)(aminobiphenyl)palladium chloride precatalyst ( commercially 
 available t - bu3p - pd - g2 ; figure 3 )
was chosen for future study as it contained a 
 relatively inexpensive phosphine ligand and demonstrated high conversion 
 of the starting material .
optimization continued by variation 
 of the temperature , solvent , 
 and catalyst loading with cs2co3 as the base 
 ( table 2 ) . with a solvent system of 1:1 dioxane / h2o , a reaction temperature of 40 c resulted in incomplete 
 conversion after 18 h ( entry 1 ) ; however , increasing the temperature 
 to 60 c provided complete conversion to the desired product 
 in 18 h ( entry 2 ) .
no side products were observed with any solvent , meaning the solvent 
 affected only the rate of the reaction .
both cyclopentyl methyl ether 
 ( cpme ) and dioxane afforded complete conversion to the desired product , 
 whereas toluene and thf did not ( entries 35 ) .
cpme was chosen 
 as the cosolvent in the reaction because of its more favorable properties 
 relative to dioxane .
because of the increased temperature , 
 decreasing the palladium loading to 1 mol % resulted in complete conversion 
 ( entry 6 ) , but when the catalyst loading was further decreased to 
 0.5 mol % , starting material remained after 18 h ( entry 7 ) .
the concentration 
 of the reaction was also screened , and complete conversion was achieved 
 with a concentration of 0.5 m ( entries 8 and 9 ) . therefore , 1 mol 
 % t - bu3p - pd - g2 , 3 equiv of cs2co3 , and 1:1 cpme / h2o at 60 c for 18 
 h were used as the standard cross - coupling conditions .
determined by hplc with the addition 
 of 10 mol % 4,4-di - tert - butylbiphenyl as 
 an internal standard .
entries 2 , 3 , 6 , 8 , and 9 resulted in complete 
 conversion of the starting material .
the general reaction conditions were applied to a 
 representative 
 set of potassium aryltrifluoroborates with 3-bromo-2-methyl-2,1-borazaronaphthalene 
 as the electrophilic partner in the cross - coupling reaction ( table 3 ) . to investigate the method fully ,
both electron - rich 
 ( entries 18 ) and electron - poor ( entries 1013 ) aryltrifluoroborates 
 were examined .
all of the aryltrifluoroborates utilized were successfully 
 cross - coupled without employing an excess of the organotrifluoroborate , 
 providing the desired 3-aryl-2,1-borazaronaphthalenes in yields of 
 5398% .
aryltrifluoroborates with ortho ( entry 
 3 ) , meta ( entries 2 , 812 , 14 ) , and para ( entries 4 , 5 , and 13 )
both 1- and 2-naphthyltrifluoroborate were 
 successful nucleophiles in this reaction , and the products were obtained 
 in yields of 93% and 95% , respectively ( entries 6 and 7 ) . when a disubstituted 
 aryltrifluoroborate was subjected to the reaction ,
the scalable nature of the cross - coupling 
 was demonstrated by performing the reaction on a 4.5 mmol scale with 
 0.5 mol % t - bu3p - pd - g2 , which provided 
 the desired products in high yield ( entries 1 and 2 ) . reaction conditions ( unless 
 otherwise noted ) : 1.0 
 equiv of 3-bromo-2-methyl-2,1-borazaronaphthalene , 1.0 equiv of potassium 
 aryltrifluoroborate , 1 mol % t - bu3p - pd - g2 , 
 3.0 equiv of base , 1:1 cpme / h2o , 60 c , 18 h. reaction concentration of 0.1 m. reaction completed on a 4.5 
 mmol 
 scale with 0.5 mol % t - bu3p - pd - g2 . to expand the range of nucleophiles , 

3-bromo-2-methyl-2,1-borazaronaphthalene 
 was coupled with a variety of potassium heteroaryltrifluoroborates 
 ( table 4 ) .
the thienyltrifluoroborates were 
 successfully cross - coupled , affording the desired products in yields 
 of 84% and 86% ( entries 2 and 3 ) .
other heteroaryltrifluoroborates , 
 including furyl and isoxazolyl , were successfully coupled , and the 
 corresponding 3-heteroaryl-2,1-borazaronaphthalenes were synthesized 
 in yields up to 72% ( entries 4 and 5 ) .
larger heteroaryltrifluoroborates , 
 such as 4-dibenzofuranyl- and 4-dibenzothienyltrifluoroborate , were 
 efficient as nucleophiles in the coupling , furnishing the products 
 in yields of 54% and 52% , respectively , after the concentration of 
 the reaction was lowered to 0.1 m ( entries 6 and 7 ) . reaction conditions ( unless otherwise noted ) : 1.0 
 equiv of 3-bromo-2-methyl-2,1-borazaronaphthalene , 1.0 equiv of potassium 
 heteroaryltrifluoroborate , 1 mol % t - bu3p - pd - g2 , 3.0 equiv of base , 1:1 cpme / h2o , 60 c , 
 18 h. reaction concentration 
 of 0.1 m. to demonstrate 
 the versatility of this method , other 3-bromo-2-alkyl-2,1-borazaronaphthalenes 
 were synthesized and subjected to the standard cross - coupling conditions 
 with potassium 3-methoxyphenyltrifluoroborate as the nucleophilic 
 partner ( table 5 ) .
brominated n - substituted b - alkyl 2,1-borazaronaphthalenes 
 were successful electrophiles in this cross - coupling reaction .
benzyl 
 and allyl substituents on nitrogen did not affect the cross - coupling , 
 providing the desired products in yields of 93% , and 83% , respectively 
 ( entries 1 and 2 ) .
the product from the cross - coupling of 3-bromo-2-(,,-trifluoroethyl)-2,1-borazaronaphthalene 
 was obtained in 67% yield , providing access to fluorinated 2,1-borazaronaphthalenes 
 ( entry 3 ) .
secondary cyclic ( cyclobutyl and cyclopropyl ) and noncyclic 
 ( isopropyl ) substituents on boron afforded the corresponding cross - coupled 
 product in yields of 70% , 84% , and 77% , respectively ( entries 46 ) .
reaction conditions : 1.0 equiv 
 of 3-bromo-2-alkyl-2,1-borazaronaphthalene , 
 1.0 equiv of potassium 3-methoxyphenyltrifluoroborate , 1 mol % t - bu3p - pd - g2 , 3.0 equiv of base , 1:1 cpme / h2o , 60 c , 18 h. after viable reaction conditions for the coupling of 3-bromo-2-alkyl-2,1-borazaronaphthalenes were determined , the coupling 
 of the corresponding 3-bromo-2-aryl-2,1-borazaronaphthalenes 
 was investigated .
although transmetalation of the b - alkyl systems would likely never compete with those of the arylboron 
 nucleophiles , aryl groups are much more easily transferred .
therefore , 
 there was concern that 3-bromo-2-aryl-2,1-borazaronaphthalenes would 
 not be stable in the cross - coupling reaction , with the potential that 
 the b - aryl group of the azaborine could compete with 
 the nucleophilic aryltrifluoroborate in the reaction , resulting in 
 a mixture of products .
fortunately , subjecting 3-bromo-2-phenyl-2,1-borazaronaphthalene 
 ( 2h ) to the reaction conditions with 1 equiv of either 
 potassium phenyltrifluoroborate or phenylboronic acid resulted in 
 the desired cross - coupled product 11a in a yield of 77% 
 or 54% , respectively ( table 6 , entry 1 ) . on 
 the basis of these results , the scope of the cross - coupling was analyzed 
 with an array of potassium ( hetero)aryltrifluoroborates ( table 6 ) .
aryltrifluoroborates with either para or meta substitution provided the desired product 
 in yields of 71% and 32% , respectively ( entries 2 and 3 ) .
several 
 heteroaryltrifluoroborates were successful nucleophiles in this coupling , 
 such as thienyl , furyl , and isoxazolyl , affording the cross - coupled 
 products in yields of 70% , 80% , and 88% , respectively ( entries 57 ) . 

the desired cross - coupled product was obtained in 75% yield when an n - boc - indolyltrifluoroborate was employed as the nucleophile 
 in the reaction ( entry 8) . reaction conditions ( unless otherwise noted ) : 1.0 
 equiv of 3-bromo-2-phenyl-2,1-borazaronaphthalene , 1.0 equiv of potassium 
 ( hetero)aryltrifluoroborate ,
1 mol % t - bu3p - pd - g2 , 3.0 equiv of base , 1:1 cpme / h2o , 60 c , 
 18 h. phenylboronic acid 
 was utilized 
 as the nucleophile . to demonstrate 
 the versatility of this method
, other 3-bromo-2-(hetero)aryl-2,1-borazaronaphthalenes 
 were synthesized and subjected to the standard cross - coupling conditions 
 with potassium 3-methoxyphenyltrifluoroborate as the nucleophilic 
 partner ( table 7 ) .
two additional 3-bromo-2-aryl-2,1-borazaronaphthalenes 
 were subjected to the cross - coupling reaction , and the corresponding 
 products were isolated in yields of 62% and 50% ( entries 1 and 2 ) . 

when the electrophile was 3-bromo-2-(3-thienyl)-2,1-borazaronaphthalene , 
 the desired product was obtained in 24% yield ( entry 3 ) .
steric hindrance 
 of the 2,1-borazaronaphthalene can affect the success of the coupling 
 reaction . for example , 3-bromo-2-(4-dibenzofuranyl)-2,1-borazaronaphthalene 
 could serve as the electrophilic partner in this reaction but afforded 
 the desired product in only 32% yield ( entry 4 ) .
reaction conditions : 1.0 equiv 
 of 3-bromo-2-(hetero)aryl-2,1-borazaronaphthalene , 
 1.0 equiv of potassium 3-methoxyphenyltrifluoroborate , 1 mol % t - bu3p - pd - g2 , 3.0 equiv of base , 1:1 cpme / h2o , 60 c , 18 h. after the analysis of the scope of the cross - coupling to include 
 both b - alkyl- and b - aryl-2,1-borazaronaphthalenes , 
 studies were directed toward accessing doubly cross - coupled products . 

addition of 2 equiv of 3-methoxyphenyltrifluoroborate to 3,6-dibromo-2-methyl-2,1-borazaronaphthalene 
 ( 2v ) provided the desired product in 97% isolated yield 
 ( eq 7).7 unfortunately , the 
 cross - coupling was not selective upon addition 
 of 1 equiv of potassium aryltrifluoroborate . therefore , to access 
 doubly cross - coupled products utilizing different potassium ( hetero)aryltrifluoroborates , 
 the product of one cross - coupling had to be subjected to a second 
 site - selective bromination . in the case of cross - coupling products 3a and 3b ,
the second bromination proceeded at 
 the 6-position to yield 6-bromo-3-(3-methoxyphenyl)-2-methyl-2,1-borazaronaphthalene 
 ( 9a ) and 6-bromo-3-phenyl-2-methyl-2,1-borazaronaphthalene 
 ( 9b ) , respectively , in moderate to good yields ( eq 8) .
rather remarkably , the borazine was brominated 
 effectively at its second most reactive site in the presence of the 
 electron - rich methoxy - substituted arene.8 these brominated 2,1-borazaronaphthalenes reacted with an 
 array 
 of potassium ( hetero)aryltrifluoroborates to provide access to highly 
 substituted 2,1-borazaronaphthalenes ( table 8) .
a 3,5-disubstituted aryltrifluoroborate reacted with 9a to provide the cross - coupled product 10a in 86% isolated 
 yield ( entry 1 ) .
heteroaryltrifluoroborates were also efficient nucleophiles 
 for this reaction , as 3-thienyltrifluoroborate and 3-furyltrifluoroborate 
 reacted with 9b to afford the desired products in 84% 
 and 69% yield , respectively ( entries 2 and 3 ) .
reaction conditions : 1.0 equiv of 6-bromo-3-aryl-2-methyl-2,1-borazaronaphthalene , 
 1.0 equiv of potassium ( hetero)aryltrifluoroborate , 1 mol % t - bu3p - pd - g2 , 3.0 equiv of base , 1:1 cpme / h2o , 60 c , 18 h. the overall impact of the approaches to borazine synthesis described 
 herein can be appreciated by comparing these tactics to those utilized 
 for the construction of various substituted naphthalenes . for example , 
 the most convenient synthesis of 2,3-disubstituted naphthalenes provides 
 the symmetrical products in good to excellent yields , but unsymmetrical naphthalenes would result in a mixture 
 of products .
the cross - coupling route described herein allows direct 
 and site - specific installation of a ( hetero)aryl unit at the c3 position , 
 thus alleviating the limitation of obtaining regioisomeric products . in a similar scenario ,
the products of the cross - coupling of brominated n - substituted 2,1-borazaronaphthalenes are isosteric to 
 1,2,3-trisubstituted naphthalenes , whose synthesis often results in 
 mixtures of regioisomers . in the case of the 
 2,1-borazaronaphthalenes , bromination and subsequent cross - coupling 

lastly , the products obtained using the 
 3,6-diaryl-2,1-borazaronaphthalenes 
 are isosteres of 2,3,6-trisubstituted naphthalenes .
there are currently 
 no examples of naphthalenes with this substitution pattern , whereas the corresponding cross - couplings described 
 herein allow the ready synthesis of such site - specific polysubstituted 
 2,1-borazaronaphthalenes in high yield .
2,1-borazaronaphthalenes 
 undergo site - selective bromination at the 3-position , whereupon addition 
 of a second equivalent of bromine allows access to 3,6-dibromo-2,1-borazaronaphthalenes . 
 in this work
furthermore , this cross - coupling easily builds molecular complexity 
 within this family of azaborines .
most of the research conducted on 
 azaborines has primarily focused on their synthesis , with limited 
 studies of their reactivity as isosteres of the all - carbon analogues . 
 before this study ,
bromine and chlorine were the only two substituents 
 reported at the 3-position of 2,1-borazaronaphthalene , and they were 
 synthesized in low to moderate yields in the early 1960s .
the methods 
 described herein expand the substitution at the c3 position to include 
 aryl and heteroaryl substituents .
most importantly , however , the protocols 
 developed demonstrate that 2,1-borazaronaphthalenes are stable toward 
 palladium catalysis , thereby allowing access to highly functionalized 
 molecules and opening the door to the exploration of azaborines in 
 other transition - metal - catalyzed reactions .
b nmr spectra were obtained on a spectrometer equipped with the appropriate 
 decoupling accessories .
all of the 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 ( multiplicity , coupling constant , integration ) . 

chemical shifts (  ) are reported in parts per million and coupling 
 constants ( j ) in hertz .
multiplicities are abbreviated 
 as follows : s = singlet , d = doublet , t = triplet , m = multiplet , 
 br = broad . 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 3-vinylphenylboronic 
 acid , 4-naphthalene-1-ylphenylboronic acid , and 3-methoxy-5-methylphenylboronic 
 are commercially available .
h nmr ( 500 mhz , dmso - d6 )  7.46 ( br s , 1h ) , 7.3 ( d , j = 6.8 hz , 1h ) , 7.18 ( d , j = 7.1 hz , 1h ) , 7.137.10 
 ( m , 1h ) , 6.726.67 ( m , 1h ) , 5.70 ( d , j = 17.9 
 hz , 1h ) , 5.14 ( d , j = 10.8 hz , 1h ) .
c nmr ( 125.8 mhz , dmso - d6 )  138.7 , 
 135.2 , 131.8 , 129.9 , 126.9 , 123.5 , 112.2 .
ir ( neat ) 1322 , 1260 , 1056 , 957 , 794 , 662 cm . 

hrms ( esi ) m / z calcd for c8h7bf3 [ m  k ] 171.0593 , 
 found 171.0586 .
h nmr ( 500 mhz , dmso - d6 )  7.967.94 ( m , 2h ) , 7.897.86 
 ( m , 1h ) , 7.637.60 ( m , 2h ) , 7.557.40 ( m , 4h ) , 7.307.27 
 ( m , 2h ) .
c nmr ( 125.8 mhz , dmso - d6 )  141.3 , 137.2 , 133.9 , 131.9 , 131.5 , 128.6 , 128.3 , 
 127.3 , 127.0 , 126.3 , 126.1 , 126.0 , 125.9 .
ir ( neat ) 3058 , 2920 , 1647 , 1394 , 1217 , 773 cm .
hrms ( esi ) m / z calcd for c16h11bf3 [ m  k ] 271.0906 , found 271.0906 .
h nmr ( 500 mhz , acetone - d6 )  6.94 ( s , 1h ) , 6.89 ( s , 1h ) , 6.48 
 ( s , 1h ) , 3.69 ( s , 3h ) , 2.22 ( s , 3h ) .
c nmr ( 125.8 mhz , 
 acetone - d6 )  158.8 , 136.3 , 124.8 , 
 113.5 , 112.1 , 54.0 , 20.7 .
ir 
 ( neat ) 2918 , 1588 , 1321 , 1287 , 1021 , 956 , 850 , 803 cm .
hrms ( esi ) m / z calcd for c8h9bof3 [ m  k ] 189.0694 , found 189.0693 . 2,1-borazaronaphthalenes 
 were synthesized according to the literature procedure . obtained as an off - white solid ( 130 mg , 21% , 3 mmol scale ) .
h nmr ( 500 mhz , acetone - d6 )  9.74 ( br s , 1h ) , 8.13 ( d , j = 11.2 hz , 1h ) , 7.70 ( d , j = 7.7 hz , 
 1h ) , 7.567.52 ( m , 1h ) , 7.477.43 ( m , 1h ) , 7.237.18 
 ( m , 1h ) , 6.946.90 ( m , 1h ) , 2.422.30 ( m , 2h ) .
c nmr ( 125.8 mhz , acetone - d6 ) 
  145.3 , 140.3 , 129.2 , 128.4 , 127.3 ( q , j = 
 278 hz ) , 125.3 , 121.1 , 118.3 .
ir ( neat ) 3361 , 2970 , 1563 , 
 1278 , 1236 , 1102 , 1032 , 768 cm . hrms ( ci ) m / z calcd for c10h9bnf3 [ m ] 211.0780 , found 211.0778 .
obtained as an 
 off - white solid ( 650 mg , 76% , 5 mmol scale ) .
h nmr ( 500 mhz , acetone - d6 )  
 9.06 ( br s , 1h ) , 8.01 ( d , j = 11.5 hz , 1h ) , 7.6 ( d , j = 7.6 hz , 1h ) , 7.537.49 ( m , 1h ) , 7.407.35 
 ( m , 1h ) , 7.137.09 ( m , 1h ) , 6.876.82 ( m , 1h ) , 1.561.48 
 ( m , 1h ) , 1.181.11 ( m , 6h ) .
c nmr ( 125.8 mhz , 
 acetone - d6 )  144.5 , 140.7 , 128.9 , 
 127.8 , 125.2 , 120.2 , 118.2 , 19.6 .
ir ( neat ) 3361 , 
 2940 , 1560 , 1438 , 1056 , 1035 , 761 cm .
hrms ( ci ) m / z calcd for c11h14bn [ m ] 171.1219 , found 171.1223 . obtained as an 
 off - white solid ( 379 mg , 69% , 3 mmol scale ) .
h nmr ( 500 mhz , acetone - d6 )  
 9.09 ( br s , 1h ) , 8.02 ( d , j = 11.5 hz , 1h ) , 7.61 
 ( d , j = 7.8 hz , 1h ) , 7.517.48 ( m , 1h ) , 7.397.35 
 ( m , 1h ) , 7.147.09 ( m , 1h ) , 6.906.85 ( m , 1h ) , 2.472.40 
 ( m , 1h ) , 2.272.11 ( m , 5h ) , 2.072.00 ( m , 1h ) .
c nmr ( 125.8 mhz , acetone - d6 ) 
  144.5 , 140.7 , 128.9 , 127.8 , 125.2 , 120.2 , 118.0 , 25.5 , 22.1 .
ir ( neat ) 3363 , 2960 , 2934 , 2858 , 1560 , 1438 , 760 
 cm .
hrms ( ci ) m / z calcd for c12h14bn [ m ] 183.1219 , 
 found 183.1212 . obtained 
 as an off - white solid ( 834 mg , 71% , 5 mmol scale ) .
h nmr ( 500 mhz , acetone - d6 )  9.77 ( br s , 1h ) , 8.18 ( d , j = 11.5 
 hz , 1h ) , 7.707.66 ( m , 2h ) , 7.637.60 ( m , 2h ) , 7.467.42 
 ( m , 1h ) , 7.397.35 ( m , 1h ) , 7.317.27 ( m , 1h ) , 7.217.17 
 ( m , 1h ) , 7.006.97 ( m , 1h ) , 3.85 ( s , 3h ) .
c nmr 
 ( 125.8 mhz , acetone - d6 )  159.6 , 
 145.4 , 141.0 , 129.0 , 129.0 , 128.2 , 125.6 , 125.4 , 120.7 , 118.5 , 118.1 , 
 114.9 , 54.4 .
ir ( neat ) 3368 , 3051 , 2406 , 1566 , 1250 , 
 1039 , 763 cm . hrms ( ci ) m / z calcd for c15h14bno [ m ] 235.1168 , found 235.1177 .
obtained as an off - white solid ( 569 mg , 56% , 3 mmol scale ) .
h nmr ( 500 mhz , cdcl3 )  8.15 ( d , j = 11.2 hz , 1h ) , 7.73 ( d , j = 7.6 hz , 1h ) , 7.407.36 ( m , 2h ) , 7.317.28 
 ( m , 1h ) , 7.237.20 ( m , 1h ) , 7.177.11 ( m , 3h ) , 7.097.01 
 ( m , 4h ) , 6.926.88 ( m , 1h ) , 5.43 ( br s , 2h ) , 3.66 ( s , 3h ) , 
 2.34 ( s , 3h ) .
c nmr ( 125.8 mhz , cdcl3 )  
 162.2 , 158.8 , 145.3 , 141.2 , 136.6 , 130.2 , 129.3 , 128.8 , 128.5 , 127.2 , 
 125.6 , 124.8 , 120.9 , 117.2 , 117.0 , 113.9 , 54.8 , 52.3 , 21.0 .
ir ( neat ) 2995 , 
 1548 , 1415 , 1255 , 1225 , 1028 , 766 cm .
hrms ( ci ) m / z calcd for c23h22bno [ m ] 339.1794 , found 339.1781 . obtained as 
 a yellow oil ( 285 mg , 52% , 3 mmol scale ) .
h nmr ( 500 mhz , 
 acetone - d6 )  7.91 ( d , j = 11.2 hz , 1h ) , 7.64 ( d , j = 7.8 hz , 1h ) , 7.527.59 
 ( m , 1h ) , 7.467.42 ( m , 1h ) , 7.177.14 ( m , 1h ) , 6.816.78 
 ( m , 1h ) , 6.086.02 ( m , 1h ) , 5.09 ( d , j = 10.5 
 hz , 1h ) , 4.91 ( d , j = 17.4 hz , 1h ) , 4.704.68 
 ( m , 2h ) , 0.81 ( s , 3h ) .
c nmr ( 125.8 mhz , acetone - d6 )  144.0 , 141.5 , 134.7 , 130.0 , 128.1 , 
 126.6 , 120.2 , 115.5 , 114.6 , 48.9 .
ir ( neat ) 3008 , 
 1609 , 1551 , 1412 , 1353 , 1219 , 757 cm . hrms ( esi ) m / z calcd for c12h14bn [ m ] 183.1219 , found 183.1215 .
obtained as a yellow oil ( 486 mg , 59% , 3 mmol scale ) .
h nmr ( 500 mhz , acetone - d6 )  8.13 
 ( d , j = 11.2 hz , 1h ) , 7.76 ( d , j = 7.8 hz , 1h ) , 7.647.61 ( m , 1h ) , 7.567.51 ( m , 1h ) , 
 7.357.31 ( m , 1h ) , 7.287.23 ( m , 1h ) , 7.187.14 
 ( m , 2h ) , 6.956.89 ( m , 2h ) , 6.186.11 ( m , 1h ) , 5.225.17 
 ( m , 1h ) , 4.994.93 ( m , 1h ) , 4.854.82 ( m , 2h ) , 3.81 
 ( s , 3h ) .
c nmr ( 125.8 mhz , acetone - d6 )  159.1 , 145.2 , 141.0 , 136.1 , 130.1 , 128.7 , 128.5 , 
 127.0 , 124.3 , 121.0 , 117.3 , 116.7 , 114.9 , 113.3 , 54.3 , 50.3 .
ir ( neat ) 3009 , 2939 , 2830 , 1549 , 1413 , 1281 , 1049 , 
 764 cm . hrms ( esi ) m / z calcd for c18h19bno [ m + h ] 276.1560 , found 276.1564 .
obtained as a white solid ( 585 mg , 54% , 3 mmol scale ) .
h nmr ( 500 mhz , cdcl3 )  8.338.30 
 ( m , 1h ) , 7.897.72 ( m , 5h ) , 7.557.35 ( m , 6h ) , 7.287.19 
 ( m , 3h ) , 5.53 ( s , 2h ) .
c nmr ( 125.8 mhz , cdcl3 )  146.3 , 141.3 , 139.2 , 132.9 , 132.5 ( q , j = 226 hz ) , 130.8 , 130.2 ( d , j = 32 hz ) , 129.2 , 
 127.8 , 127.4 , 125.9 , 124.6 ( d , j = 3 hz ) , 123.8 , 
 121.8 , 117.4 , 52.8 .
ir ( neat ) 2923 , 1551 , 1233 , 859 , 762 , 682 , 632 cm . hrms
( ci ) m / z calcd 
 for c22h17bnf3 [ m ] 363.1406 , 
 found 363.1403 . obtained as a white solid ( 700 mg , 68% , 3 mmol scale ) .
h nmr ( 500 mhz , cdcl3 )  8.19 
 ( d , j = 11.5 hz , 1h ) , 7.77 ( d , j = 7.3 hz , 1h ) , 7.607.57 ( m , 2h ) , 7.467.41 ( m , 2h ) , 
 7.287.25 ( m , 1h ) , 7.117.09 ( m , 5h ) , 6.926.90 
 ( m , 2h ) , 5.43 ( s , 2h ) , 3.83 ( s , 3h ) .
c nmr ( 125.8 mhz , 
 cdcl3 )  163.1 ( d , j = 245 hz ) , 
 158.5 , 145.5 , 141.2 , 134.5 ( d , j = 7 hz ) , 131.02 , 
 130.3 , 128.6 , 127.3 , 126.7 , 121.1 , 117.1 , 114.7 ( d , j = 20 hz ) , 114.3 , 55.2 , 51.8 .
ir ( neat ) 3027 , 1550 , 1414 , 1234 , 787 , 761 , 
 731 cm . hrms ( ci ) m / z calcd for c22h19bnof [ m ] 343.1544 , 
 found 343.1540 . to a flame - dried 100 ml round - bottom 
 flask with a stir bar was 
 added the corresponding 2,1-borazaronaphthalene ( 2.0 mmol ) .
the flask 
 was sealed with a rubber septum , evacuated under vacuum , and purged 
 with ar three times .
anhydrous ch2cl2 ( 10 ml ) 
 was added , and the flask was cooled to 0 c .
bromine ( 352 mg , 
 2.2 mmol , 1.1 equiv ) in ch2cl2 ( 10 ml ) was added 
 under ar at a rate of 1.1 mmol / h .
the reaction was monitored by tlc , 
 and when it was complete ( usually after warming to rt ) , the reaction 
 mixture was concentrated in vacuo .
the crude 2,1-borazaronaphthalene 
 was purified by flash column chromatography with 030% ch2cl2/hexane as the eluent to provide the desired 
 3-bromo-2,1-borazaronaphthalene .
obtained as an off - white solid ( 1969 mg , 
 99% , 9 mmol scale ) .
h nmr ( 500 mhz , acetone - d6 )  9.63 ( br s , 1h ) , 8.29 ( s , 1h ) , 7.62 
 ( d , j = 7.8 hz , 1h ) , 7.477.42 ( m , 2h ) , 7.177.14 
 ( m , 1h ) , 0.79 ( s , 3h ) .
c nmr ( 125.8 mhz , acetone - d6 )  144.3 , 140.2 , 128.6 , 128.55 , 124.9 , 
 121.2 , 118.2 .
ir ( neat ) 3361 , 2940 , 1560 , 1438 , 1056 , 
 1035 , 761 cm .
hrms ( ci ) m / z calcd for c9h9brbn [ m ] 221.0011 , found 221.0019 . obtained as an off - white solid ( 138 mg , 
 96% , 0.5 mmol scale ) .
h nmr ( 500 
 mhz , acetone - d6 )  9.87 ( br s , 1h ) , 
 8.44 ( s , 1h ) , 7.717.64 ( m , 2h ) , 7.537.49 ( m , 1h ) , 
 7.267.23 ( m , 1h ) , 2.555.49 ( m , 2h ) .
c 
 nmr ( 125.8 mhz , acetone - d6 )  146.2 , 
 139.5 , 129.3 , 128.8 , 128.7 ( q , j = 274 hz ) , 125.2 , 
 122.3 , 118.8 .
ir ( neat ) 3361 , 2970 , 1563 , 1278 , 1236 , 
 1102 , 1032 , 768 cm . hrms ( ci ) m / z calcd for c10h8brbnf3 [ m ] 288.9885 , found 288.9884 .
obtained as an off - white solid ( 488 mg , 
 98% , 2 mmol scale ) . 

h nmr ( 500 mhz , acetone - d6 )  9.26 ( br s , 1h ) , 8.33 ( s , 1h ) , 7.657.57 
 ( m , 2h ) , 7.457.41 ( m , 1h ) , 7.207.15 ( m , 1h ) , 1.851.80 
 ( m , 1h ) , 1.191.15 ( m , 6h ) .
c nmr ( 125.8 mhz , 
 acetone - d6 )  145.5 , 140.1 , 128.6 , 
 128.5 , 125.0 , 121.4 , 118.5 , 18.6 .
ir ( neat ) 3373 , 
 2956 , 2852 , 1610 , 1558 , 1424 , 1137 , 849 , 757 cm . hrms ( ci ) m / z calcd for c11h13brbn [ m ] 249.0324 , found 249.0330 .
obtained as an off - white solid ( 689 mg , 93% , 3 mmol scale ) . 

h nmr ( 500 mhz , acetone - d6 )  8.87 ( br s , 1h ) , 8.28 ( s , 1h ) , 7.617.58 
 ( m , 1h ) , 7.467.42 ( m , 1h ) , 7.417.38 ( m , 1h ) , 7.147.10 
 ( m , 1h ) , 0.880.86 ( m , 2h ) , 0.850.82 ( m , 2h ) , 0.770.73 
 ( m , 1h ) .
c nmr ( 125.8 mhz , acetone - d6 )  144.6 , 140.3 , 128.6 , 128.5 , 124.7 , 121.0 , 118.1 , 
 6.1 .
ir ( neat ) 3374 , 2954 , 1557 , 1428 , 1105 , 925 , 
 848 , 748 cm . hrms ( ci ) m / z calcd for c11h11brbn [ m ] 247.0168 , found 247.0159 .
obtained as an off - white solid ( 506 mg , 
 97% , 2 mmol scale ) . 

h nmr ( 500 mhz , acetone - d6 )  9.33 ( br s , 1h ) , 8.28 ( s , 1h ) , 7.647.60 
 ( m , 2h ) , 7.467.42 ( m , 1h ) , 7.197.15 ( m , 1h ) , 2.652.61 
 ( m , 1h ) , 2.262.15 ( m , 5h ) , 1.971.93 ( m , 1h ) .
c nmr ( 125.8 mhz , acetone - d6 ) 
  145.0 , 140.0 , 128.6 , 128.5 , 125.0 , 121.4 , 118.5 , 25.0 , 21.8 .
ir ( neat ) 3353 , 2979 , 1612 , 1557 , 1428 , 1205 , 927 , 
 757 cm . hrms ( ci ) m / z calcd for c12h13brbn [ m ] 261.0324 , 
 found 261.0330 .
obtained as an off - white solid ( 886 mg , 
 95% , 3 mmol scale ) . 

h nmr ( 500 mhz , acetone - d6 )  8.34 ( s , 1h ) , 7.657.63 ( m , 
 1h ) , 7.407.33 ( m , 2h ) , 7.237.12 ( m , 6h ) , 5.38 ( s , 
 2h ) , 0.97 ( s , 3h ) .
c nmr ( 125.8 mhz , acetone - d6 )  144.8 , 140.6 , 138.0 , 129.5 , 128.8 , 
 128.6 , 127.0 , 126.0 , 125.7 , 121.3 , 116.3 , 51.6 .
ir ( neat ) 2917 , 1608 , 1359 , 1028 , 753 , 735 , 722 , 697 cm .
hrms ( ci ) m / z calcd for c16h15brbn [ m ] 311.0481 , found 311.0490 . obtained as a yellow oil ( 781 mg , 98% , 3 mmol scale ) .
h nmr ( 500 mhz , acetone - d6 )  
 8.25 ( s , 1h ) , 7.62 ( d , j = 7.8 hz , 1h ) , 7.48 ( d , j = 3.4 hz , 2h ) , 7.207.16 ( m , 1h ) , 6.086.00 
 ( m , 1h ) , 5.135.08 ( m , 1h ) , 4.944.90 ( m , 1h ) , 4.744.72 
 ( m , 2h ) , 0.92 ( s , 3h ) .
c nmr ( 125.8 mhz , acetone - d6 )  144.5 , 140.5 , 134.1 , 129.5 , 128.7 , 
 125.8 , 121.1 , 115.9 , 115.0 , 50.0 .
ir ( neat ) 3031 , 
 1607 , 1362 , 1216 , 913 , 760 , 741 cm . hrms ( ci ) m / z calcd for c12h13bbrn [ m ] 261.0324 , found 261.0330 .
obtained as an off - white solid ( 840 mg , 
 99% , 3 mmol scale ) .
h nmr ( 500 mhz , acetone - d6 )  9.90 ( br s , 1h ) , 8.54 ( s , 1h ) , 7.957.92 
 ( m , 2h ) , 7.757.71 ( m , 2h ) , 7.547.51 ( m , 1h ) , 7.457.40 
 ( m , 3h ) , 7.277.23 ( m , 1h ) .
c nmr ( 125.8 mhz , 
 acetone - d6 )  146.7 , 140.1 , 133.5 , 
 128.9 , 128.8 , 128.5 , 127.4 , 124.9 , 121.6 , 118.6 .
ir ( neat ) 3371 , 3052 , 1552 , 1420 , 1009 , 761 , 748 , 702 cm .
hrms ( ci ) m / z calcd for c14h11brbn [ m ] 283.0168 , found 283.0174 . obtained as an off - white solid ( 325 mg , 52% , 2 mmol scale ) . 

h nmr ( 500 mhz , acetone - d6 )  9.87 ( br s , 1h ) , 8.54 ( s , 1h ) , 7.727.69 
 ( m , 2h ) , 7.537.48 ( m , 3h ) , 7.377.34 ( m , 1h ) , 7.267.23 
 ( m , 1h ) , 7.016.97 ( m , 1h ) , 3.84 ( s , 3h ) .
c nmr 
 ( 125.8 mhz , acetone - d6 )  159.0 , 
 146.8 , 140.1 , 128.9 , 128.6 , 128.5 , 125.8 , 124.9 , 121.7 , 119.0 , 118.6 , 
 114.4 , 54.5 .
ir ( neat ) 3323 , 2970 , 2933 , 1557 , 1427 , 
 1252 , 1047 , 791 cm .
hrms ( ci ) m / z calcd for c15h14bbrno [ m 
 + h ] 314.0352 , found 314.0341 . obtained as an off - white solid ( 274 mg , 
 91% , 2 mmol scale ) . 

h nmr ( 500 mhz , acetone - d6 )  9.89 ( br s , 1h ) , 8.50 ( s , 1h ) , 7.997.96 
 ( m , 2h ) , 7.697.66 ( m , 2h ) , 7.527.49 ( m , 1h ) , 7.247.18 
 ( m , 3h ) .
c nmr ( 125.8 mhz , acetone - d6 )  163.6 ( d , j = 246 hz ) , 146.8 , 
 140.1 , 135.9 ( d , j = 7.5 hz ) , 128.9 , 128.5 , 124.9 , 
 121.7 , 118.6 , 114.3 ( d , j = 20.2 hz ) .
ir ( neat ) 3376 , 3055 , 1615 , 1593 , 1425 , 1214 , 800 , 757 cm . hrms ( ci ) m / z calcd 
 for c14h10bbrfn [ m ] 301.0074 , found 
 301.0080 .
obtained as a light - brown solid ( 305 mg , 
 53% , 2 mmol scale ) . 

h nmr ( 500 mhz , acetone - d6 )  9.91 ( br s , 1h ) , 8.52 ( s , 1h ) , 8.358.32 
 ( m , 1h ) , 7.83 ( d , j = 4.9 hz , 1h ) , 7.70 ( d , j = 8.1 hz , 1h ) , 7.66 ( d , j = 8.1 hz , 1h ) , 
 7.577.54 ( m , 1h ) , 7.537.48 ( m , 1h ) , 7.257.20 
 ( m , 1h ) .
c nmr ( 125.8 mhz , acetone - d6 )  146.8 , 140.0 , 133.7 , 132.0 , 128.9 , 128.5 , 124.8 , 
 124.7 , 121.5 , 118.4 .
ir ( neat ) 3749 , 2977 , 2349 , 
 1557 , 758 cm .
hrms ( ci ) m / z calcd for c12h10bbrns [ m + h ] 289.9810 , found 289.9810 . obtained as an off - white solid ( 663 mg , 
 89% , 
 2 mmol scale ) .
h nmr ( 500 mhz , 
 acetone - d6 )  10.33 ( br s , 1h ) , 
 8.66 ( s , 1h ) , 8.188.13 ( m , 2h ) , 7.96 ( d , j = 7.3 hz , 1h ) , 7.82 ( d , j = 7.9 hz , 1h ) , 7.787.76 
 ( m , 1h ) , 7.637.57 ( m , 2h ) , 7.537.47 ( m , 2h ) , 7.417.38 
 ( m , 1h ) , 7.347.31 ( m , 1h ) .
c nmr ( 125.8 mhz , 
 acetone - d6 )  159.0 , 156.0 , 147.0 , 
 140.0 , 133.2 , 129.3 , 128.9 , 127.3 , 125.3 , 124.3 , 123.2 , 123.0 , 122.6 , 
 122.2 , 121.8 , 120.9 , 119.0 , 111.8 .
ir ( neat ) 3382 , 
 3036 , 1567 , 1185 , 748 , 726 cm .
hrms ( ci ) m / z calcd for c20h13bbrno [ m ] 373.0274 , found 373.0276 . obtained as a white solid ( 513 mg , 53% , 
 3 mmol scale ) . 

h nmr ( 500 mhz , acetone - d6 )  8.51 ( s , 1h ) , 7.787.74 ( m , 
 1h ) , 7.637.56 ( m , 2h ) , 7.507.47 ( m , 2h ) , 7.437.37 
 ( m , 3h ) , 7.337.28 ( m , 1h ) , 6.035.96 ( m , 1h ) , 5.13 
 ( d , j = 10.5 hz , 1h ) , 4.944.90 ( m , 1h ) , 4.734.71 
 ( m , 2h ) .
c nmr ( 125.8 mhz , acetone - d6 )  146.1 , 140.0 , 135.0 , 131.4 , 129.6 , 129.0 , 127.8 , 
 127.4 , 126.4 , 121.9 , 117.1 , 115.3 , 51.4 .
ir ( neat ) 
 2979 , 1607 , 1586 , 1544 , 1368 , 1245 , 965 , 701 cm . hrms ( esi ) m / z calcd for c17h15brbn [ m ] 323.0481 , found 323.0494 .
obtained as a yellow oil ( 324 mg , 46% , 
 2 mmol scale ) .
h nmr ( 500 mhz , acetone - d6 )  8.52 ( s , 1h ) , 7.807.78 ( m , 1h ) , 7.647.55 
 ( m , 2h ) , 7.347.30 ( m , 2h ) , 7.066.94 ( m , 2h ) , 6.966.93 
 ( m , 1h ) , 6.056.00 ( m , 1h ) , 5.175.13 ( m , 1h ) , 4.954.92 
 ( m , 1h ) , 4.764.73 ( m , 2h ) , 3.80 ( s , 3h ) .
c nmr 
 ( 125.8 mhz , acetone - d6 )  158.9 , 
 146.1 , 140.0 , 135.2 , 129.6 , 129.0 , 128.7 , 126.4 , 123.5 , 121.9 , 117.0 , 
 116.8 , 115.2 , 113.2 , 54.3 , 51.4 .
ir ( neat ) 2953 , 1644 , 1545 , 
 1366 , 1282 , 1048 , 763 cm .
hrms ( esi ) m / z calcd for c18h18brbno [ m 
 + h ] 354.0665 , found 354.0657 . obtained as an off - white solid ( 710 mg , 
 95% , 2 mmol scale ) . 

h nmr ( 500 mhz , acetone - d6 )  8.58 ( br s , 1h ) , 7.79 ( d , j = 7.6 hz , 1h ) , 7.497.41 ( m , 4h ) , 7.367.30 
 ( m , 3h ) , 7.287.23 ( m , 3h ) , 7.207.17 ( m , 1h ) , 7.147.09 
 ( m , 2h ) , 5.39 ( s , 2h ) .
c nmr ( 125.8 mhz , acetone - d6 )  146.4 , 140.0 , 138.4 , 131.5 , 129.7 , 
 129.0 , 128.6 , 127.9 , 127.5 , 126.8 , 126.7 , 125.5 , 122.0 , 117.5 , 53.0 .
ir ( neat ) 3025 , 1606 , 1545 , 1367 , 1355 , 1243 , 971 , 
 763 , 723 , 703 cm . hrms ( ci ) m / z calcd for c21h17brbn [ m ] 373.0637 , found 373.0638 .
obtained as an off - white solid ( 211 mg , 
 48% , 1 mmol scale ) .
h nmr ( 500 
 mhz , acetone - d6 )  8.61 ( s , 1h ) , 
 7.81 ( d , j = 7.9 hz , 1h ) , 7.717.67 ( m , 4h ) , 
 7.467.42 ( m , 2h ) , 7.297.25 ( m , 3h ) , 7.217.18 
 ( m , 1h ) , 7.137.11 ( m , 2h ) , 5.36 ( s , 2h ) .
c nmr 
 ( 125.8 mhz , acetone - d6 )  147.0 , 
 140.1 , 138.3 , 132.3 , 130.1 , 129.8 , 129.5 ( q , j = 
 4 hz ) , 128.9 , 128.0 , 127.3 , 127.1 , 127.0 ( q , j = 
 272 hz ) , 125.8 , 122.5 , 117.7 , 53.4 .
ir ( neat ) 3029 , 
 1546 , 1323 , 1122 , 834 , 725 cm . hrms ( ci ) m / z calcd for c22h16brbf3n [ m ] 441.0511 , found 441.0511 .
obtained as an off - white solid ( 207 mg , 
 49% , 1 mmol scale ) .
h nmr ( 500 
 mhz , acetone - d6 )  8.56 ( s , 1h ) , 
 7.78 ( d , j = 7.8 hz , 1h ) , 7.537.41 ( m , 4h ) , 
 7.277.24 ( m , 1h ) , 7.137.10 ( m , 2h ) , 7.047.00 
 ( m , 2h ) , 6.876.85 ( m , 2h ) , 5.31 ( s , 2h ) , 3.71 ( s , 3h ) .
c nmr ( 125.8 mhz , acetone - d6 ) 
  162.8 ( d , j = 245 hz ) , 158.8 , 146.4 , 140.0 , 
 133.7 ( d , j = 8 hz ) , 130.0 , 129.7 , 129.0 , 126.7 , 
 126.6 , 122.0 , 117.5 , 114.3 ( d , j = 20 hz ) , 114.0 , 
 54.5 , 52.4 .
ir ( neat ) 2971 , 1550 , 1414 , 1234 , 762 , 
 625 cm .
hrms ( ci ) m / z calcd for c22h18brbnof [ m ] 421.0649 , 
 found 421.0654 . obtained as an off - white solid ( 237 mg , 
 25% , 
 2.5 mmol scale ) .
h nmr ( 500 mhz , 
 acetone - d6 )  8.56 ( s , 1h ) , 7.817.80 
 ( m , 1h ) , 7.567.54 ( m , 1h ) , 7.507.48 ( m , 1h ) , 7.467.41 
 ( m , 2h ) , 7.327.29 ( m , 2h ) , 7.277.21 ( m , 3h ) , 7.167.14 
 ( m , 2h ) , 5.44 ( s , 2h ) .
c nmr ( 125.8 mhz , acetone - d6 )  146.3 , 138.6 , 131.7 , 131.0 , 129.7 , 
 129.6 , 129.0 , 128.7 , 126.9 , 126.6 , 125.5 , 124.8 , 122.0 , 117.4 , 53.2 .
ir ( neat ) 2958 , 1733 , 1540 , 758 , 719 cm . hrms ( ci ) m / z calcd for c19h15brbns [ m ] 379.0202 , found 379.0208 .
obtained as an off - white solid ( 337 mg , 
 81% , 1 mmol scale ) .
h nmr ( 500 
 mhz , acetone - d6 )  8.57 ( s , 1h ) , 
 7.79 ( d , j = 7.8 hz , 1h ) , 7.477.42 ( m , 2h ) , 
 7.297.26 ( m , 2h ) , 7.107.05 ( m , 2h ) , 7.037.00 
 ( m , 4h ) , 6.906.87 ( m , 1h ) , 5.35 ( s , 2h ) , 3.66 ( s , 3h ) , 2.24 
 ( s , 3h ) .
c nmr ( 125.8 mhz , acetone - d6 )  158.9 , 146.4 , 140.0 , 136.3 , 135.5 , 129.6 , 129.2 , 
 129.0 , 128.7 , 126.7 , 125.5 , 123.5 , 121.9 , 117.5 , 116.7 , 113.4 , 54.2 , 
 52.8 , 20.0 .
ir ( neat ) 3048 , 1406 , 1336 , 1313 , 1094 , 
 875 , 792 , 704 cm . hrms ( ci ) m / z calcd for c23h21brbno [ m ] 417.0900 , found 417.0913 .
obtained as a yellow oil ( 83 mg , 29% , 1 
 mmol scale ) .
h nmr ( 500 mhz , acetone - d6 )  
 9.96 ( br s , 1h ) , 8.40 ( s , 1h ) , 7.66 ( d , j = 8.1 hz , 
 1h ) , 7.597.57 ( m , 1h ) , 7.507.47 ( m , 1h ) , 7.227.19 
 ( m , 1h ) , 2.40 ( t , j = 6.8 hz , 2h ) , 1.591.49 
 ( m , 4h ) , 0.950.90 ( m , 3h ) .
c nmr ( 500 mhz , acetone - d6 )  145.1 , 139.6 , 128.8 , 128.5 , 124.7 , 
 121.6 , 118.1 , 109.5 , 30.5 , 21.5 , 19.1 , 12.9 .
ir ( neat ) 
 3649 , 2956 , 2931 , 1613 , 1556 , 997 , 799 , 759 cm . hrms ( ci ) m / z calcd for c14h15bnbr [ m ] 287.0481 , found 287.0481 .
obtained as a white solid ( 50 mg , 77% , 0.2 mmol 
 scale ) .
h nmr ( 500 mhz , cdcl3 )  8.25 ( s , 1h ) , 7.477.44 ( m , 1h ) , 7.347.31 
 ( m , 2h ) , 7.287.25 ( m , 1h ) , 7.147.10 ( m , 3h ) , 7.006.97 
 ( m , 1h ) , 5.35 ( s , 2h ) , 2.34 ( s , 3h ) , 1.00 ( s , 3h ) .
c 
 nmr ( 500 mhz , cdcl3 )  144.5 , 140.8 , 138.9 , 137.8 , 
 129.2 , 128.7 , 127.0 , 125.7 , 123.9 , 122.6 , 116.2 , 51.9 , 22.1 .
ir ( neat ) 
 2926 , 1590 , 1452 , 1364 , 809 , 685 cm . hrms ( ci ) m / z calcd for c17h17bnbr [ m ] 325.0637 , found 325.0647 .
obtained as a white solid ( 24 mg , 64% , 
 0.1 mmol scale ) .
h nmr ( 500 mhz , 
 cdcl3 )  8.17 ( s , 1h ) , 7.317.22 ( m , 3h ) , 
 7.157.11 ( m , 2h ) , 6.93 ( s , 1h ) , 6.73 ( s , 1h ) , 5.31 ( s , 2h ) , 
 3.89 ( s , 3h ) , 3.67 ( s , 3h ) , 1.01 ( s , 3h ) .
c nmr ( 500 
 mhz , cdcl3 ) 150.3 , 144.4 , 140.1 , 138.1 , 136.2 , 129.1 , 127.5 , 
 126.0 , 119.7 , 110.0 , 55.2 , 55.9 , 52.9 .
ir ( neat ) 2924 , 1258 , 1029 , 823 , 810 , 
 751 , 687 , 609 cm . hrms ( ci ) m / z calcd for c18h19bno2br [ m ] 371.0692 , found 371.0683 .
obtained as an off - white solid ( 221 mg , 
 34% , 2 mmol scale ) . 

h nmr ( 500 mhz , acetone - d6 )  9.60 ( br s , 1h ) , 8.13 ( d , j = 11.6 hz , 1h ) , 7.697.67 ( m , 1h ) , 7.517.43 
 ( m , 2h ) , 7.217.17 ( m , 1h ) , 6.936.91 ( m , 1h ) , 4.914.85 
 ( m , 1h ) , 4.23 ( d , j = 10.7 hz , 1h ) , 1.98 ( d , j = 6.4 hz , 3h ) .
c nmr ( 500 mhz , acetone - d6 )  145.9 , 139.7 , 129.2 , 128.4 , 125.5 , 
 121.2 , 118.4 , 50.5 , 25.4 .
ir ( neat ) 3360 , 2978 , 1614 , 
 1562 , 1441 , 760 cm .
hrms ( ci ) m / z calcd for c11h13bbr2n [ m + h ] 327.9508 , found 327.9509 . obtained as an off - white solid ( 167 mg , 
 51% , 1 mmol scale ) .
h nmr ( 500 
 mhz , acetone - d6 )  9.47 ( br s , 1h ) , 
 7.72 ( s , 1h ) , 7.66 ( d , j = 7.6 hz , 1h ) , 7.557.51 
 ( m , 2h ) , 7.447.41 ( m , 1h ) , 7.177.14 ( m , 1h ) , 6.906.87 
 ( m , 1h ) , 6.826.80 ( m , 1h ) , 3.80 ( s , 3h ) , 0.65 ( s , 3h ) .
c nmr ( 125.8 mhz , acetone - d6 ) 
  159.3 , 147.1 , 141.6 , 140.8 , 133.0 , 129.5 , 128.5 , 124.6 , 120.8 , 
 117.9 , 115.7 , 113.7 , 113.4 , 55.1 .
ir ( neat ) 3382 , 
 2987 , 1616 , 1457 , 1345 , 122 , 1014 , 759 cm .
hrms 
 ( ci ) m / z calcd for c16h16bbrno [ m + h ] 328.0508 , found 328.0518 .
obtained as an off - white solid ( 240 mg , 81% , 1 mmol scale ) . 

h nmr ( 500 mhz , acetone - d6 ) 9.58 ( br s , 1h ) , 7.867.83 ( m , 2h ) , 
 7.517.48 ( m , 1h ) , 7.447.38 ( m , 5h ) , 7.307.28 
 ( m , 1h ) , 0.88 ( s , 3h ) .
c nmr ( 125.8 mhz , acetone - d6 )  144.6 , 140.1 , 139.4 , 131.3 , 130.6 , 
 128.3 , 128.2 , 126.8 , 126.3 , 119.7 , 112.6 .
ir ( neat ) 
 3350 , 2961 , 1606 , 1439 , 1313 , 821 , 702 cm .
hrms 
 ( ci ) m / z calcd for c15h13bbrn [ m ] 297.0324 , found 297.0330 . to a flame - dried 100 ml round - bottom flask with a stir bar was 
 added the corresponding 2,1-borazaronaphthalene ( 2.0 mmol ) .
the flask 
 was sealed with a rubber septum , evacuated under vacuum , and purged 
 with ar three times .
anhydrous ch2cl2 was added 
 ( 10 ml ) , and the flask was cooled to 0 c . bromine ( 703 mg , 4.4 
 mmol , 2.2 equiv ) in ch2cl2 ( 10 ml ) was added 
 under ar at a rate of 1.1 mmol / h . after the addition , the reaction 
 mixture was slowly warmed to rt .
the reaction was monitored by tlc , 
 and when it was complete ( usually after warming to rt ) , the reaction 
 mixture was concentrated in vacuo .
the crude 2,1-borazaronaphthalene 
 was purified by flash column chromatography with 030% ch2cl2/hexane as the eluent to provide the desired 
 3,6-dibromo-2,1-borazaronaphthalene .
obtained as an off - white solid ( 822 mg , 
 92% , 3 mmol scale ) . 

h nmr ( 500 mhz , acetone - d6 )  9.70 ( br s , 1h ) , 8.268.22 
 ( m , 1h ) , 7.77 ( s , 1h ) , 7.527.50 ( m , 1h ) , 7.407.38 
 ( m , 1h ) , 0.78 ( s , 3h ) .
c nmr ( 125.8 mhz , acetone - d6 )  143.2 , 139.1 , 131.2 , 130.5 , 126.4 , 
 120.2 , 113.1 .
ir ( neat ) 3350 , 2961 , 1554 , 1423 , 1195 , 
 911 , 861 , 811 cm .
hrms ( ci ) m / z calcd for c9h8br2bn [ m ] 298.9117 , found 298.9125 . in a biotage microwave vial equipped with a stir bar were successively 
 introduced t - bu3p - pd - g2 ( 3.8 mg , 7.5 mol , 
 1 mol % ) , potassium ( hetero)aryltrifluoroborate ( 0.75 mmol , 1 equiv ) , 
 3-bromo-2-methyl-2,1-borazaronaphthalene ( 167 mg , 0.75 mmol , 1 equiv ) , 
 and cs2co3 ( 731 mg , 2.25 mmol , 3 equiv ) .
the 
 vial was sealed with a cap lined with a disposable teflon septum , 
 evacuated under vacuum , and purged with ar three times .
degassed cpme 
 ( 0.75 ml ) and degassed h2o ( 0.75 ml ) were added under ar . 

the resulting mixture was heated at 60 c and stirred for 18 
 h. after cooling to rt , the vial was uncapped , and the reaction mixture 
 was diluted with etoac ( 3 ml ) and h2o ( 3 ml ) .
the reaction 
 mixture was extracted with etoac ( 3  3 ml ) and dried ( mgso4 ) .
the solvent was removed in vacuo , and the product was purified 
 by rapid flash column chromatography on silica gel 
 or neutral alumina using 0 to 20% ch2cl2/hexane 
 as the eluent for most 2,1-borazaronaphthalenes .
the cross - couplings for tables 58 were completed 
 on a 0.5 mmol scale .
h nmr ( 500 
 mhz , acetone - d6 )  9.41 ( br s , 1h ) , 
 7.91 ( s , 1h ) , 7.69 ( d , j = 7.69 hz , 1h ) , 7.517.45 
 ( m , 3h ) , 7.437.40 ( m , 3h ) , 7.307.27 ( m , 1h ) , 7.177.14 
 ( m , 1h ) , 0.84 ( s , 3h ) .
c nmr ( 125.8 mhz , acetone - d6 )  145.0 , 141.2 , 140.3 , 129.3 , 128.1 , 
 128.0 , 127.9 , 125.8 , 125.0 , 120.5 , 117.5 .
ir ( neat ) 
 3373 , 3054 , 1613 , 1563 , 1454 , 1421 , 756 , 700 cm . hrms ( ci ) m / z calcd for c15h14bn [ m ] 219.1219 , found 219.1223 .
h 
 nmr ( 500 mhz , acetone - d6 ) 9.43 
 ( br s , 1h ) , 7.93 ( s , 1h ) , 7.69 ( d , j = 7.6 hz , 1h ) , 
 7.49 ( d , j = 8.3 hz , 1h ) , 7.427.38 ( m , 1h ) , 
 7.347.30 ( m , 1h ) , 7.177.13 ( m , 1h ) , 7.047.00 
 ( m , 2h ) , 6.886.85 ( m , 1h ) , 3.83 ( s , 3h ) , 0.81 ( s , 3h ) .
c nmr ( 125.8 mhz , acetone - d6 ) 
  159.7 , 146.5 , 141.1 , 140.3 , 129.3 , 129.0 , 127.9 , 124.9 , 120.5 , 
 120.5 , 117.5 , 113.7 , 111.3 , 54.5 .
ir ( neat ) 3346 , 
 3001 , 1573 , 1461 , 1225 , 1019 , 753 cm .
hrms ( ci ) m / z calcd for c16h16bno [ m ] 249.1325 , found 249.1325 . obtained as a yellow oil ( 176 mg , 94% ) .
h nmr ( 500 mhz , acetone - d6 )  
 9.28 ( br s , 1h ) , 7.76 ( s , 1h ) , 7.64 ( d , j = 7.6 hz , 
 1h ) , 7.48 ( d , j = 8.3 hz , 1h ) , 7.407.37 ( m , 
 1h ) , 7.297.26 ( m , 1h ) , 7.217.19 ( m , 1h ) , 7.147.11 
 ( m , 1h ) , 7.016.98 ( m , 2h ) , 3.74 ( s , 3h ) , 0.62 ( s , 3h ) .
c nmr ( 125.8 mhz , acetone - d6 ) 
  156.5 , 141.0 , 140.3 , 134.4 , 129.5 , 129.0 , 127.6 , 127.5 , 125.0 , 
 120.4 , 120.3 , 117.5 , 110.4 , 54.5 .
ir ( neat ) 3372 , 
 2997 , 2939 , 2832 , 1596 , 1458 , 1417 , 1220 , 759 , 750 , 702 cm . hrms ( ci ) m / z calcd for c16h16bno [ m ] 249.1325 , found 249.1317 .
reaction performed with a concentration 
 of 0.1 m. obtained as an off - white solid ( 173 mg , 67% ) .
h nmr ( 500 mhz , acetone - d6 )  9.49 ( br s , 1h ) , 8.038.01 ( m , 2h ) , 8.007.98 
 ( m , 1h ) , 7.977.95 ( m , 1h ) , 7.737.71 ( m , 1h ) , 7.607.57 
 ( m , 2h ) , 7.537.45 ( m , 8h ) , 7.177.15 ( m , 1h ) , 0.91 
 ( s , 3h ) .
c nmr ( 125.8 mhz , acetone - d6 )  144.1 , 141.4 , 140.4 , 140.1 , 138.2 , 134.0 , 131.6 , 
 129.8 , 129.7 , 129.3 , 128.3 , 128.1 , 128.0 , 127.5 , 126.8 , 126.0 , 125.7 , 
 125.6 , 125.4 , 125.0 , 120.6 , 117.5 .
ir ( neat ) 3375 , 
 3051 , 1614 , 1565 , 1425 , 1220 , 844 , 800 , 777 , 759 cm . hrms ( ci ) m / z calcd for c25h20bn [ m ] 345.1689 , found 345.1690 .
h nmr ( 500 mhz , acetone - d6 )  9.41 ( br s , 1h ) , 7.88 ( s , 1h ) , 7.67 ( d , j = 7.8 hz , 1h ) , 7.48 ( d , j = 7.48 hz , 
 1h ) , 7.407.37 ( m , 1h ) , 7.357.33 ( m , 2h ) , 7.217.19 
 ( m , 2h ) , 7.157.12 ( m , 1h ) , 2.35 ( s , 3h ) , 0.81 ( s , 3h ) .
c nmr ( 125.8 mhz , acetone - d6 ) 
  142.0 , 140.7 , 140.2 , 135.1 , 129.2 , 128.7 , 127.9 , 127.7 , 125.0 , 
 120.5 , 117.5 , 20.2 .
ir ( neat ) 3383 , 3022 , 2938 , 
 1613 , 1566 , 1454 , 1425 , 879 , 822 , 759 , 749 cm . 

hrms ( ci ) m / z calcd for c16h16bn [ m ] 233.1376 , found 233.1374 . obtained as a yellow oil ( 187 mg , 93% ) . 

h nmr ( 500 mhz , acetone - d6 )  9.55 ( br s , 1h ) , 7.93 ( d , j = 8.1 
 hz , 1h ) , 7.87 ( s , 1h ) , 7.847.82 ( m , 1h ) , 7.78 ( d , j = 8.6 hz , 1h ) , 7.707.76 ( m , 1h ) , 7.597.55 
 ( m , 1h ) , 7.547.51 ( m , 1h ) , 7.497.44 ( m , 2h ) , 7.417.37 
 ( m , 1h ) , 7.347.31 ( m , 1h ) , 7.207.16 ( m , 1h ) , 0.49 
 ( s , 3h ) .
c nmr ( 125.8 mhz , acetone - d6 )  143.4 , 142.3 , 140.6 , 133.8 , 131.8 , 129.2 , 128.1 , 
 128.0 , 127.7 , 136.4 , 126.3 , 125.7 , 125.5 , 125.4 , 125.3 , 124.8 , 120.6 , 
 117.7 .
ir ( neat ) 3369 , 3053 , 2980 , 1613 , 1566 , 1421 , 
 777 , 759 cm . hrms ( ci ) m / z calcd for c19h16bn [ m ] 269.1376 , found 269.1368 .
h nmr ( 500 mhz , acetone - d6 )  9.50 ( br s , 1h ) , 8.04 ( s , 1h ) , 7.957.85 
 ( m , 4h ) , 7.747.71 ( m , 1h ) , 7.677.64 ( m , 1h ) , 7.547.51 
 ( m , 1h ) , 7.507.41 ( m , 3h ) , 7.197.16 ( m , 1h ) , 0.81 
 ( s , 3h ) .
c nmr ( 125.8 mhz , acetone - d6 )  142.7 , 141.6 , 140.4 , 133.8 , 132.1 , 129.3 , 128.0 , 
 127.8 , 127.7 , 127.5 , 127.3 , 126.1 , 125.9 , 125.7 , 125.2 , 125.0 , 120.1 , 
 117.6 .
ir ( neat ) 3366 , 3053 , 2979 , 1561 , 1308 , 758 , 
 744 cm .
hrms ( ci ) m / z calcd for c19h16bn [ m ] 269.1376 , 
 found 269.1372 . obtained as a yellow oil ( 128 mg , 71% ) .
h 
 nmr ( 500 mhz , acetone - d6 )  9.45 
 ( br s , 1h ) , 7.93 ( s , 1h ) , 7.737.69 ( m , 1h ) , 7.567.47 
 ( m , 2h ) , 7.447.34 ( m , 4h ) , 7.177.13 ( m , 1h ) , 6.866.80 
 ( m , 1h ) , 5.86 ( d , j = 17.4 hz , 1h ) , 5.25 ( d , j = 10.8 hz , 1h ) , 0.81 ( s , 3h ) .
c nmr ( 125.8 
 mhz , acetone - d6 )  145.3 , 141.2 , 
 140.3 , 137.4 , 137.2 , 129.2 , 128.2 , 127.9 , 127.7 , 125.9 , 124.9 , 123.6 , 
 120.5 , 117.5 , 113.0 .
ir ( neat ) 2917 , 2848 , 1596 , 
 1422 , 1161 , 1036 , 761 cm .
hrms ( ci ) m / z calcd for c16h16bno [ m ] 249.1325 , found 249.1325 . obtained as a yellow oil ( 174 mg , 73% ) .
h nmr ( 500 mhz , acetone - d6 )  
 9.53 ( br s , 1h ) , 8.00 ( s , 1h ) , 7.72 ( d , j = 7.6 hz , 
 1h ) , 7.517.48 ( m , 1h ) , 7.467.42 ( m , 1h ) , 7.34 ( s , 
 1h ) , 7.26 ( s , 1h ) , 7.197.15 ( m , 2h ) , 3.93 ( s , 3h ) , 0.81 ( s , 
 3h ) .
c nmr ( 125.8 mhz , acetone - d6 )  160.0 , 147.7 , 142.0 , 140.1 , 130.9 ( q , j = 32 hz ) , 129.5 , 128.4 , 126.6 ( q , j = 260 hz ) , 
 124.6 , 120.6 , 117.6 , 117.4 , 116.8 ( q , j = 3.7 hz ) , 
 107.9 ( q , j = 3.7 hz ) , 55.0 .
ir ( neat ) 
 3378 , 2940 , 2842 , 1598 , 1354 , 1121 , 1057 , 759 , 692 cm . hrms ( ci ) m / z calcd for c17h15bnof3 [ m ] 317.1199 , 
 found 317.1207 .
h nmr ( 500 mhz , acetone - d6 )  9.56 ( br s , 1h ) , 8.26 ( s , 1h ) , 8.13 ( d , j = 7.8 hz , 1h ) , 8.00 ( s , 1h ) , 7.85 ( d , j = 7.6 hz , 1h ) , 7.72 ( d , j = 7.8 hz , 1h ) , 7.677.64 
 ( m , 1h ) , 7.517.48 ( m , 1h ) , 7.477.42 ( m , 1h ) , 7.187.15 
 ( m , 1h ) , 0.80 ( s , 3h ) .
c nmr ( 125.8 mhz , acetone - d6 )  148.4 , 146.7 , 142.5 , 140.6 , 134.4 , 
 129.6 , 129.3 , 128.6 , 124.5 , 122.3 , 120.7 , 120.5 , 117.6 .
ir ( neat ) 3376 , 3054 , 2967 , 1609 , 1579 , 1417 , 1253 , 879 , 759 , 
 749 , 698 cm .
hrms ( ci ) m / z calcd for c15h13bn2o2 [ m ] 264.1070 , found 264.1080 . obtained as a yellow oil ( 182 mg , 88% ) .
h nmr ( 500 mhz , acetone - d6 )  
 9.45 ( br s , 1h ) , 8.18 ( s , 1h ) , 7.93 ( s , 2h ) , 7.737.69 ( m , 
 2h ) , 7.527.47 ( m , 2h ) , 7.447.42 ( m , 1h ) , 7.177.13 
 ( m , 1h ) , 3.90 ( s , 3h ) , 0.80 ( s , 3h ) .
c nmr ( 125.8 mhz , 
 acetone - d6 )  166.6 , 145.3 , 141.7 , 
 140.5 , 132.6 , 130.2 , 129.4 , 128.9 , 128.3 , 128.2 , 126.7 , 124.8 , 120.6 , 
 117.6 , 51.4 .
ir ( neat ) 3354 , 3051 , 2949 , 1711 , 1567 , 
 1436 , 1306 , 756 cm .
hrms ( esi ) m / z calcd for c17h17bno2 [ m + h ] 278.1352 , found 278.1342 . obtained as a yellow oil ( 160 mg , 90% ) .
h 
 nmr ( 500 mhz , acetone - d6 )  9.48 
 ( br s , 1h ) , 7.93 ( s , 1h ) , 7.69 ( d , j = 7.6 hz , 1h ) , 
 7.49 ( d , j = 8.1 hz , 1h ) , 7.437.40 ( m , 2h ) , 
 7.277.24 ( m , 1h ) , 7.207.13 ( m , 2h ) , 7.057.02 
 ( m , 1h ) , 0.81 ( s , 3h ) .
c nmr ( 125.8 mhz , acetone - d6 )  163.8 ( d , j = 248 
 hz ) , 147.6 ( d , j = 7.6 hz ) , 141.7 , 140.5 , 129.70 
 ( d , j = 8.8 hz ) , 129.3 , 128.2 , 124.7 , 120.1 ( d , j = 2.5 hz ) , 120.6 , 117.6 , 116.5 ( d , j = 
 20.1 hz ) , 112.3 ( d , j = 11.2 hz ) .
ir ( neat ) 3376 , 3054 , 2967 , 1609 , 1579 , 1417 , 1253 , 879 , 759 , 749 , 
 698 cm .
hrms ( ci ) m / z calcd for c15h13bnf [ m ] 237.1125 , 
 found 237.1120 . obtained as an off - white solid ( 156 mg , 
 88% ) .
h nmr ( 500 mhz , acetone - d6 ) 9.54 ( br s , 1h ) , 7.95 ( s , 1h ) , 7.737.69 
 ( m , 3h ) , 7.637.61 ( m , 2h ) , 7.527.49 ( m , 1h ) , 7.457.42 
 ( m , 1h ) , 7.177.14 ( m , 1h ) , 0.80 ( s , 3h ) .
c nmr 
 ( 125.8 mhz , acetone - d6 )  149.2 , 
 142.2 , 140.6 , 129.5 , 128.6 , 128.5 , 127.3 ( q , j = 
 32 hz ) , 124.8 ( q , j = 276 hz ) , 124.9 ( q , j = 3.8 hz ) , 123.7 , 120.7 , 117.6 .
ir ( neat ) 
 3346 , 3030 , 1614 , 1334 , 1325 , 110 , 1071 , 762 , 755 cm . hrms ( ci ) m / z calcd for c16h13bnf3 [ m ] 287.1093 , found 
 287.1093 . obtained as an off - white solid ( 145 mg , 
 79% ) .
h nmr ( 500 mhz , acetone - d6 )  9.59 ( br s , 1h ) , 8.00 ( s , 1h ) , 7.81 ( s , 1h ) , 7.787.73 
 ( m , 2h ) , 7.707.67 ( m , 1h ) , 7.657.60 ( m , 1h ) , 7.527.49 
 ( m , 1h ) , 7.467.43 ( m , 1h ) , 7.177.14 ( m , 1h ) , 0.79 
 ( s , 3h ) .
c nmr ( 125.8 mhz , acetone - d6 )  146.3 , 142.3 , 140.6 , 132.7 , 131.3 , 129.5 , 129.3 , 
 129.2 , 128.5 , 124.6 , 120.7 , 118.7 , 117.6 , 112.1 .
ir ( neat ) 3338 , 2980 , 1558 , 1260 , 1088 , 945 , 793 cm .
hrms ( ci ) m / z calcd for c16h13bn2 [ m ] 244.1172 , found 
 244.1174 . obtained as an off - white solid ( 150 mg , 
 56% ) .
h nmr ( 500 mhz , acetone - d6 )  9.42 ( br s , 1h ) , 8.20 ( d , j = 8.3 hz , 1h ) , 7.94 ( s , 1h ) , 7.707.67 ( m , 1h ) , 
 7.667.64 ( m , 2h ) , 7.507.48 ( m , 1h ) , 7.447.38 
 ( m , 2h ) , 7.167.13 ( m , 1h ) , 6.696.67 ( m , 1h ) , 1.69 
 ( s , 9h ) , 0.83 ( s , 3h ) .
c nmr ( 125.8 mhz , acetone - d6 )  149.4 , 141.0 , 140.2 , 139.7 , 133.8 , 
 130.8 , 129.1 , 127.7 , 126.0 , 125.0 , 124.8 , 120.5 , 120.0 , 117.5 , 114.5 , 
 107.4 , 83.3 , 27.3 .
ir ( neat ) 3375 , 2976 , 1730 , 
 1370 , 1160 , 1134 , 759 , 749 , 727 cm .
hrms ( ci ) m / z calcd for c22h23bn2o2 [ m ] 358.1853 , found 358.1856 . obtained as an off - white solid ( 145 mg , 86% ) .
h nmr ( 500 mhz , acetone - d6 )  9.41 ( br s , 1h ) , 8.10 ( s , 1h ) , 7.677.64 
 ( m , 1h ) , 7.477.44 ( m , 2h ) , 7.407.37 ( m , 3h ) , 7.167.13 
 ( m , 1h ) , 0.90 ( s , 3h ) .
c nmr ( 125.8 mhz , acetone - d6 )  145.8 , 140.41 , 140.4 , 129.4 , 128.1 , 
 128.0 , 128.0 , 125.2 , 120.8 , 120.8 , 117.9 .
ir ( neat ) 
 3372 , 3052 , 2938 , 1612 , 1563 , 1426 , 878 , 777 , 758 , 748 cm . hrms ( ci ) m / z calcd for c13h12bns [ m ] 225.0784 , found 225.0789 .
h 
 nmr ( 500 mhz , acetone - d6 )  9.50 
 ( br s , 1h ) , 8.13 ( s , 1h ) , 7.68 ( d , j = 7.8 hz , 1h ) , 
 7.477.44 ( m , 1h ) , 7.427.39 ( m , 1h ) , 7.367.34 
 ( m , 1h ) , 7.287.25 ( m , 1h ) , 7.167.13 ( m , 1h ) , 7.117.08 
 ( m , 1h ) , 0.95 ( s , 3h ) .
c nmr ( 125.8 mhz , acetone - d6 )  147.7 , 140.1 , 139.8 , 129.1 , 128.0 , 
 127.6 , 124.6 , 124.5 , 123.9 , 120.8 , 117.5 .
ir ( neat ) 
 3371 , 3056 , 2945 , 1612 , 1560 , 1426 , 1336 , 877 , 757 , 693 cm . hrms ( ci ) m / z calcd for c13h12bns [ m ] 225.0784 , found 225.0784 .
h nmr ( 500 mhz , acetone - d6 )  9.58 ( br s , 1h ) , 8.27 ( s , 1h ) , 7.6 
 ( d , j = 7.3 hz , 1h ) , 7.477.41 ( m , 2h ) , 7.167.13 
 ( m , 1h ) , 1.58 ( s , 3h ) , 1.39 ( s , 3h ) , 0.81 ( s , 3h ) .
c 
 nmr ( 125.8 mhz , acetone - d6 )  163.1 , 
 158.3 , 144.1 , 140.6 , 129.1 , 128.3 , 124.5 , 120.5 , 118.3 , 117.7 , 10.5 , 
 9.7 .
ir ( neat ) 3372 , 3052 , 2967 , 1613 , 1566 , 1449 , 
 1187 , 777 , 749 cm . hrms ( ci ) m / z calcd for c14h15bn2o [ m ] 238.1277 , found 238.1283 .
h 
 nmr ( 500 mhz , acetone - d6 )  9.41 
 ( br s , 1h ) , 8.09 ( s , 1h ) , 7.79 ( s , 1h ) , 7.677.65 ( m , 1h ) , 
 7.617.58 ( m , 1h ) , 7.477.43 ( m , 1h ) , 7.387.35 
 ( m , 1h ) , 7.147.11 ( m , 1h ) , 6.876.89 ( m , 1h ) , 0.89 
 ( s , 3h ) .
c nmr ( 125.8 mhz , acetone - d6 )  142.9 , 139.9 , 139.7 , 138.8 , 128.9 , 128.6 , 127.5 , 
 124.9 , 120.5 , 117.4 , 109.4 .
ir ( neat ) 3362 , 2932 , 1614 , 
 1426 , 1031 , 872 , 760 cm .
hrms ( ci ) m / z calcd for c13h12bno [ m ] 209.1012 , found 209.1006 .
reaction performed with a concentration 
 of 0.1 
 m. obtained as an off - white solid ( 125 mg , 54% ) .
h nmr ( 500 mhz , acetone - d6 )  
 9.56 ( br s , 1h ) , 8.13 ( s , 1h ) , 8.09 ( d , j = 7.6 hz , 
 1h ) , 8.00 ( dd , j = 7.1 hz , 1.5 hz , 1h ) , 7.747.71 
 ( m , 1h ) , 7.597.54 ( m , 2h ) , 7.497.41 ( m , 4h ) , 7.387.34 
 ( m , 1h ) , 7.197.17 ( m , 1h ) , 0.73 ( s , 3h ) .
c nmr 
 ( 125.8 mhz , acetone - d6 )  155.9 , 
 153.5 , 142.8 , 140.6 , 129.8 , 129.4 , 128.3 , 127.6 , 127.0 , 124.7 , 124.4 , 
 123.9 , 123.0 , 122.7 , 120.7 , 120.6 , 118.6 , 117.7 , 111.4 .
ir ( neat ) 3374 , 3052 , 2968 , 1614 , 1566 , 1425 , 1187 , 777 , 749 
 cm . hrms ( ci ) m / z calcd for c21h16bno [ m ] 309.1325 , 
 found 309.1313 .
reaction performed with a concentration 
 of 0.1 
 m. obtained as an off - white solid ( 127 mg , 52% ) .
h nmr ( 500 mhz , acetone - d6 )  
 9.63 ( br s , 1h ) , 8.31 ( d , j = 7.8 hz , 1h ) , 8.22 ( d , j = 7.8 hz , 1h ) , 8.10 ( s , 1h ) , 7.907.88 ( m , 1h ) , 
 7.727.70 ( m , 1h ) , 7.597.54 ( m , 2h ) , 7.507.45 
 ( m , 3h ) , 7.387.35 ( m , 1h ) , 7.217.18 ( m , 1h ) , 0.66 
 ( s , 3h ) .
c nmr ( 125.8 mhz , acetone - d6 )  142.1 , 140.8 , 140.2 , 139.5 , 138.6 , 136.1 , 135.5 , 
 129.4 , 128.5 , 126.6 , 126.4 , 124.8 , 124.4 , 124.3 , 122.5 , 121.8 , 120.7 , 
 119.3 , 117.7 .
ir ( neat ) 3366 , 3056 , 2980 , 1707 , 1567 , 
 1440 , 1021 , 749 cm .
hrms ( ci ) m / z calcd for c21h16bns [ m ] 325.1097 , found 325.1086 . obtained as a yellow oil ( 157 mg , 93% ) .
h nmr ( 500 mhz , acetone - d6 ) 7.92 
 ( s , 1h ) , 7.74 ( d , j = 7.6 hz , 1h ) , 7.42 ( d , j = 8.3 hz , 1h ) , 7.357.27 ( m , 4h ) , 7.237.21 
 ( m , 1h ) , 7.207.16 ( m , 3h ) , 7.016.98 ( m , 2h ) , 6.906.87 
 ( m , 1h ) , 5.44 ( s , 2h ) , 3.83 ( s , 3h ) , 0.86 ( s , 3h ) .
c 
 nmr ( 125.8 mhz , acetone - d6 )  159.6 , 
 146.8 , 141.8 , 141.0 , 138.5 , 130.3 , 128.9 , 128.6 , 128.3 , 126.7 , 126.1 , 
 125.7 , 120.9 , 120.8 , 115.8 , 114.1 , 111.3 , 54.5 , 50.9 .
ir ( neat ) 3027 , 1734 , 1604 , 1368 , 1046 , 727 cm . hrms ( ci ) m / z calcd for c23h22bno [ m ] 339.1794 , found 339.1786 .
h nmr ( 500 mhz , acetone - d6 ) 7.85 
 ( s , 1h ) , 7.72 ( d , j = 7.3 hz , 1h ) , 7.567.53 
 ( m , 1h ) , 7.497.45 ( m , 1h ) , 7.337.28 ( m , 1h ) , 7.217.17 
 ( m , 1h ) , 6.956.93 ( m , 2h ) , 6.886.84 ( m , 1h ) , 6.146.07 
 ( m , 1h ) , 5.13 ( d , j = 10.5 hz , 1h ) , 4.97 ( d , j = 17.4 hz , 1h ) , 4.814.79 ( m , 2h ) , 3.83 ( s , 3h ) , 
 0.84 ( s , 3h ) .
c nmr ( 125.8 mhz , acetone - d6 )  159.6 , 146.8 , 141.5 , 140.8 , 134.7 , 130.3 , 128.9 , 
 128.2 , 125.9 , 120.8 , 120.6 , 115.4 , 114.7 , 114.0 , 111.2 , 54.5 , 49.3 .
ir ( neat ) 3648 , 2979 , 1734 , 1367 , 1047 , 761 cm .
hrms ( ci ) m / z calcd 
 for c19h20bno [ m ] 289.1638 , found 
 289.1649 .
h nmr ( 500 mhz , acetone - d6 )  
 9.66 ( br s , 1h ) , 8.03 ( s , 1h ) , 7.77 ( d , j = 7.8 hz , 
 1h ) , 7.70 ( d , j = 8.1 hz , 1h ) , 7.517.48 ( m , 
 1h ) , 7.377.33 ( m , 1h ) , 7.287.24 ( m , 1h ) , 6.986.96 
 ( m , 2h ) , 6.916.88 ( m , 1h ) , 3.84 ( s , 3h ) , 2.48 ( q , j = 14.2 hz , 2h ) .
c nmr ( 125.8 mhz , acetone - d6 )  159.9 , 145.6 , 143.0 , 139.7 , 129.4 , 
 129.2 , 128.9 ( q , j = 272 hz ) , 128.5 , 125.0 , 121.6 , 
 120.5 , 118.2 , 113.7 , 111.6 , 54.5 .
ir ( neat ) 3408 , 
 2961 , 1699 , 1596 , 1240 , 1038 , 760 cm .
hrms ( esi ) m / z calcd for c17h14bnof3 [ m  h ] 316.1121 , found 
 316.1120 .
h nmr ( 500 mhz , acetone - d6 )  
 9.12 ( br s , 1h ) , 7.87 ( s , 1h ) , 7.67 ( d , j = 7.6 hz , 
 1h ) , 7.61 ( d , j = 8.1 hz , 1h ) , 7.427.39 ( m , 
 1h ) , 7.337.30 ( m , 1h ) , 7.177.14 ( m , 1h ) , 6.986.96 
 ( m , 2h ) , 6.886.86 ( m , 1h ) , 3.83 ( s , 3h ) , 1.931.90 
 ( m , 1h ) , 1.101.07 ( m , 6h ) .
c nmr ( 125.8 mhz , 
 acetone - d6 )  159.6 , 146.9 , 142.1 , 
 140.3 , 129.1 , 128.9 , 127.9 , 124.7 , 120.7 , 120.4 , 117.9 , 113.7 , 111.1 , 
 54.5 , 19.3 .
ir ( neat ) 3380 , 2938 , 1732 , 1574 , 1461 , 
 1280 , 760 cm .
hrms ( ci ) m / z calcd for c18h20bno [ m ] 277.1638 , found 277.1637 . obtained as yellow oil ( 115 mg , 84% ) .
h nmr ( 500 mhz , acetone - d6 )  
 8.64 
 ( br s , 1h ) , 7.88 ( s , 1h ) , 7.66 ( d , j = 7.8 hz , 1h ) , 
 7.48 ( d , j = 8.3 hz , 1h ) , 7.377.31 ( m , 2h ) , 
 7.157.10 ( m , 3h ) , 6.686.65 ( m , 1h ) , 3.83 ( s , 3h ) , 
 0.830.80 ( m , 2h ) , 0.750.72 ( m , 2h ) , 0.540.50 
 ( m , 1h ) .
c nmr ( 125.8 mhz , acetone - d6 )  159.6 , 146.3 , 141.0 , 140.4 , 129.2 , 128.9 , 127.9 , 
 124.7 , 120.7 , 120.4 , 117.6 , 113.9 , 111.3 , 54.5 , 6.4 .
ir ( neat ) 3382 , 2993 , 1597 , 1464 , 1258 , 1046 , 760 cm .
hrms ( ci ) m / z calcd for c18h18bno [ m ] 275.1481 , found 275.1476 . obtained as yellow oil ( 101 mg , 70% ) .
h nmr 
 ( 500 mhz , acetone - d6 )  9.18 
 ( br s , 1h ) , 7.88 ( s , 1h ) , 7.68 ( d , j = 7.6 hz , 1h ) , 
 7.63 ( d , j = 7.8 hz , 1h ) , 7.437.40 ( m , 1h ) , 
 7.307.27 ( m , 1h ) , 7.177.14 ( m , 1h ) , 6.966.92 
 ( m , 2h ) , 6.866.83 ( m , 1h ) , 3.82 ( s , 3h ) , 2.752.70 
 ( m , 1h ) , 2.122.04 ( m , 5h ) , 1.931.85 ( m , 1h ) .
c nmr ( 125.8 mhz , acetone - d6 ) 
  159.6 , 146.5 , 141.6 , 140.2 , 129.2 , 128.8 , 127.9 , 124.9 , 120.7 , 
 120.3 , 117.8 , 113.4 , 111.2 , 54.5 , 25.6 , 21.5 .
ir ( neat ) 
 3381 , 2962 , 1596 , 1461 , 1046 , 758 , 703 cm .
hrms 
 ( ci ) m / z calcd for c19h20bno [ m ] 289.1638 , found 289.1635 .
h nmr ( 500 mhz , acetone - d6 )  
 9.70 ( br s , 1h ) , 8.07 ( s , 1h ) , 7.79 ( d , j = 7.8 hz , 
 1h ) , 7.737.70 ( m , 1h ) , 7.507.45 ( m , 3h ) , 7.317.22 
 ( m , 9h ) .
c nmr ( 125.8 mhz , acetone - d6 )  144.6 , 143.3 , 140.4 , 133.5 , 129.3 , 128.6 , 128.3 , 
 128.1 , 127.8 , 127.3 , 125.8 , 125.2 , 121.1 , 118.2 .
ir ( neat ) 3371 , 3051 , 2923 , 1560 , 1420 , 1307 , 756 cm .
hrms ( ci ) m / z calcd for c20h16bn [ m ] 281.1376 , found 281.1371 . obtained as a yellow oil ( 106 mg , 71% ) .
h 
 nmr ( 500 mhz , acetone - d6 )  9.70 
 ( br s , 1h ) , 8.06 ( s , 1h ) , 7.777.75 ( m , 1h ) , 7.71 ( d , j = 8.1 hz , 1h ) , 7.487.45 ( m , 3h ) , 7.317.24 
 ( m , 6h ) , 7.067.01 ( m , 2h ) .
c nmr ( 125.8 mhz , 
 acetone - d6 )  161.6 ( d , j = 243 hz ) , 143.4 , 140.8 ( d , j = 2.5 hz ) , 
 140.4 , 133.4 , 130.3 ( d , j = 7.5 hz ) , 129.4 , 128.4 , 
 128.2 , 127.4 , 125.1 , 121.1 , 118.2 , 114.5 ( d , j = 
 21 hz ) .
ir ( neat ) 3381 , 3050 , 2979 , 2348 , 1698 , 
 1218 , 834 , 753 cm . hrms ( ci ) m / z calcd for c20h15bfn [ m ] 299.1282 , found 299.1280 .
h nmr ( 500 mhz , acetone - d6 )  9.83 ( br s , 1h ) , 8.25 ( s , 1h ) , 8.22 ( s , 1h ) , 8.138.08 
 ( m , 1h ) , 7.84 ( d , j = 7.8 hz , 1h ) , 7.757.72 
 ( m , 1h ) , 7.687.65 ( m , 1h ) , 7.547.50 ( m , 2h ) , 7.467.43 
 ( m , 2h ) , 7.337.24 ( m , 4h ) .
c nmr ( 125.8 mhz , 
 acetone - d6 )  148.2 , 146.4 , 144.5 , 
 140.7 , 135.1 , 133.3 , 129.7 , 129.0 , 128.9 , 128.3 , 127.5 , 124.9 , 122.9 , 
 121.4 , 120.5 , 118.3 .
ir ( neat ) 3371 , 3051 , 2780 , 
 1560 , 1286 , 1264 , 756 , 699 cm . hrms ( esi ) m / z calcd for c20h15bn2o2na [ m + na ] 349.1124 , found 
 349.1125 . obtained as an off - white solid ( 88 mg , 
 52% ) .
h nmr ( 500 mhz , acetone - d6 )  9.61 ( br s , 1h ) , 8.04 ( s , 1h ) , 7.76 
 ( d , j = 7.8 hz , 1h ) , 7.707.68 ( m , 1h ) , 7.537.51 
 ( m , 2h ) , 7.477.43 ( m , 1h ) , 7.337.27 ( m , 3h ) , 7.237.20 
 ( m , 1h ) , 6.82 ( s , 1h ) , 6.746.72 ( m , 2h ) , 4.254.20 
 ( m , 4h ) .
c nmr ( 125.8 mhz , acetone - d6 )  143.3 , 142.7 , 142.3 , 140.2 , 137.8 , 133.3 , 129.2 , 
 128.1 , 128.0 , 127.3 , 125.2 , 121.7 , 121.1 , 118.1 , 117.0 , 116.4 , 65.2 , 
 64.1 .
ir ( neat ) 3355 , 2980 , 1560 , 1506 , 1412 , 1307 , 
 1281 , 1244 , 754 cm .
hrms ( ci ) m / z calcd for c22h19bno2 [ m + h ] 340.1509 , found 340.1516 . obtained as an off - white solid ( 100 mg , 
 70% ) .
h nmr ( 500 mhz , acetone - d6 )  9.63 ( br s , 1h ) , 8.22 ( s , 1h ) , 7.75 ( d , j = 7.8 hz , 1h ) , 7.707.67 ( m , 1h ) , 7.567.52 
 ( m , 2h ) , 7.477.43 ( m , 1h ) , 7.367.29 ( m , 4h ) , 7.237.20 
 ( m , 1h ) , 7.167.14 ( m , 1h ) , 7.087.06 ( m , 1h ) .
c nmr ( 125.8 mhz , acetone - d6 ) 
  145.1 , 142.3 , 140.2 , 133.1 , 129.2 , 128.4 , 128.2 , 128.1 , 127.4 , 
 125.2 , 124.6 , 121.2 , 120.8 , 118.2 .
ir ( neat ) 3372 , 
 2979 , 2919 , 1613 , 1559 , 1423 , 754 cm .
hrms ( ci ) m / z calcd for c18h14bns [ m ] 287.0940 , found 287.0939 . obtained as a dark - yellow oil ( 104 mg , 
 80% ) .
h nmr ( 500 mhz , acetone - d6 )  9.61 
 ( br s , 1h ) , 8.24 ( s , 1h ) , 7.75 ( d , j = 7.8 hz , 1h ) , 
 7.667.64 ( m , 1h ) , 7.607.57 ( m , 2h ) , 7.497.43 
 ( m , 2h ) , 7.397.37 ( m , 3h ) , 7.237.21 ( m , 2h ) , 6.85 
 ( s , 1h ) .
c nmr ( 125.8 mhz , acetone - d6 )  142.6 , 140.8 , 140.0 , 139.8 , 132.6 , 129.0 , 128.2 , 
 128.0 , 127.9 , 127.5 , 125.2 , 121.2 , 118.1 , 109.9 .
ir ( neat ) 3353 , 2979 , 1706 , 1506 , 1318 , 951 , 815 , 703 cm .
hrms ( ci ) m / z calcd for c18h14bno [ m ] 271.1168 found 271.1156 . obtained as a white solid ( 132 mg , 88% ) . 

h nmr ( 500 mhz , acetone - d6 )  9.84 ( br s , 1h ) , 8.04 ( s , 1h ) , 7.787.74 
 ( m , 2h ) , 7.547.50 ( m , 3h ) , 7.347.29 ( m , 3h ) , 7.267.23 
 ( m , 1h ) , 2.11 ( s , 3h ) , 1.86 ( s , 3h ) .
c nmr ( 125.8 mhz , 
 acetone - d6 )  163.4 , 158.5 , 146.0 , 
 140.7 , 132.8 , 129.2 , 128.7 , 128.5 , 127.6 , 124.8 , 121.2 , 118.4 , 118.3 , 
 10.5 , 9.8 .
ir ( neat ) 3378 , 1615 , 1423 , 1156 , 756 , 
 709 cm . hrms ( esi ) m / z calcd for c19h18bn2o 
 [ m + h ] 301.1512 , found 301.1521 .
h nmr ( 500 mhz , acetone - d6 )  9.65 ( br s , 1h ) , 8.11 ( s , 1h ) , 8.078.04 
 ( m , 1h ) , 7.797.77 ( m , 1h ) , 7.737.71 ( m , 1h ) , 7.637.62 
 ( m , 1h ) , 7.537.47 ( m , 4h ) , 7.297.21 ( m , 5h ) , 6.576.56 
 ( m , 1h ) , 1.67 ( s , 9h ) .
c nmr ( 125.8 mhz , acetone - d6 )  149.4 , 143.4 , 140.3 , 139.4 , 133.5 , 
 130.7 , 129.2 , 128.1 , 128.0 , 127.3 , 125.9 , 125.5 , 125.3 , 121.1 , 120.5 , 
 118.2 , 114.2 , 107.3 , 83.3 , 59.6 , 27.4 .
ir ( neat ) 
 3371 , 2975 , 1731 , 1370 , 1162 , 1135 , 764 , 752 cm . hrms ( esi ) m / z calcd for c27h25bn2o2na [ m + na ] 443.1907 , found 443.1902 .
h nmr ( 500 mhz , acetone - d6 )  9.73 ( br s , 1h ) , 8.08 ( s , 1h ) , 7.77 
 ( d , j = 7.8 hz , 1h ) , 7.69 ( d , j = 
 8.3 hz , 1h ) , 7.537.44 ( m , 3h ) , 7.257.18 ( m , 2h ) , 7.057.00 
 ( m , 2h ) , 6.876.80 ( m , 3h ) , 3.67 ( s , 3h ) .
c nmr 
 ( 125.8 mhz , acetone - d6 )  163.2 
 ( d , j = 250 hz ) , 159.5 , 145.9 , 143.3 , 140.4 , 135.7 , 
 135.6 , 129.4 , 128.9 , 128.4 , 125.1 , 121.2 , 120.9 , 118.2 , 114.1 ( d , j = 20.5 hz ) , 111.6 , 54.3 .
ir ( neat ) 3371 , 
 2928 , 1595 , 1570 , 1417 , 1277 , 1161 , 760 cm .
hrms 
 ( ci ) m / z calcd for c21h18bnof [ m + h ] 330.1465 , found 330.1466 .
h nmr ( 500 mhz , acetone - d6 )  9.68 ( br s , 1h ) , 8.10 ( s , 1h ) , 7.797.77 
 ( m , 1h ) , 7.727.70 ( m , 1h ) , 7.497.46 ( m , 1h ) , 7.247.18 
 ( m , 3h ) , 7.097.05 ( m , 2h ) , 6.906.86 ( m , 3h ) , 6.816.79 
 ( m , 1h ) , 3.67 ( s , 3h ) , 3.65 ( s , 3h ) .
c nmr ( 125.8 mhz , 
 acetone - d6 )  159.4 , 158.9 , 146.0 , 
 143.1 , 140.4 , 129.3 , 128.7 , 128.4 , 128.3 , 125.6 , 125.1 , 121.2 , 120.9 , 
 118.6 , 118.2 , 114.2 , 113.9 , 115.6 , 54.3 , 54.1 .
ir ( neat ) 3344 , 3006 , 2938 , 1597 , 1223 , 1037 , 786 , 703 cm .
hrms ( esi ) m / z calcd for c22h21bno2 [ m + h ] 342.1665 , 
 found 342.1650 . obtained as a yellow oil ( 39 mg , 24% ) .
h nmr ( 500 mhz , acetone - d6 )  
 9.74 
 ( br s , 1h ) , 8.01 ( s , 1h ) , 7.75 ( d , j = 8.1 hz , 1h ) , 
 7.66 ( d , j = 8.1 hz , 1h ) , 7.577.55 ( m , 1h ) , 
 7.487.45 ( m , 1h ) , 7.397.36 ( m , 1h ) , 7.277.18 
 ( m , 3h ) , 6.936.84 ( m , 3h ) , 3.73 ( s , 3h ) .
c nmr 
 ( 125.8 mhz , acetone - d6 )  159.4 , 
 146.5 , 143.1 , 140.3 , 132.0 , 131.9 , 129.3 , 128.8 , 128.3 , 124.9 , 124.3 , 
 121.0 , 120.8 , 118.0 , 114.0 , 111.7 , 54.3 .
ir ( neat ) 
 3374 , 2924 , 1562 , 1261 , 852 , 761 , 685 cm .
hrms 
 ( ci ) m / z calcd for c19h17bnos [ m + h ] 318.1124 , found 318.1109 .
h nmr ( 500 mhz , acetone - d6 )  10.11 ( br s , 1h ) , 8.24 ( s , 1h ) , 8.088.04 
 ( m , 2h ) , 7.87 ( d , j = 7.8 hz , 1h ) , 7.787.76 
 ( m , 1h ) , 7.557.41 ( m , 4h ) , 7.377.34 ( m , 1h ) , 7.317.25 
 ( m , 2h ) , 7.137.10 ( m , 1h ) , 6.946.92 ( m , 1h ) , 6.916.90 
 ( m , 1h ) , 6.716.68 ( m , 1h ) , 3.53 ( s , 3h ) .
c nmr 
 ( 125.8 mhz , acetone - d6 )  159.4 , 
 158.9 , 155.8 , 145.9 , 143.1 , 140.0 , 132.8 , 129.5 , 128.7 , 128.4 , 126.9 , 
 125.3 , 124.1 , 122.8 , 122.5 , 122.3 , 121.4 , 120.7 , 120.6 , 120.5 , 118.3 , 
 113.6 , 111.7 , 111.4 , 54.2 .
ir ( neat ) 3390 , 3051 , 2929 , 
 1564 , 1450 , 1165 , 756 cm .
hrms ( esi ) m / z calcd for c27h21bno2 [ m + h ] 402.1665 , found 402.1673 . obtained as a yellow oil ( 172 mg , 97% ) .
h nmr ( 500 mhz , acetone - d6 )  
 9.50 
 ( br s , 1h ) , 8.048.01 ( m , 2h ) , 7.757.71 ( m , 1h ) , 7.577.55 
 ( m , 1h ) , 7.397.27 ( m , 4h ) , 7.037.01 ( m , 2h ) , 6.906.86 
 ( m , 2h ) , 3.86 ( s , 3h ) , 3.84 ( s , 3h ) , 0.85 ( s , 3h ) .
c 
 nmr ( 125.8 mhz , acetone - d6 )  160.3 , 
 159.7 , 146.4 , 142.2 , 141.3 , 139.9 , 133.3 , 129.7 , 129.0 , 127.4 , 126.9 , 
 125.1 , 120.5 , 118.9 , 118.0 , 113.7 , 112.2 , 112.1 , 111.4 , 54.6 , 54.5 .
ir ( neat ) 3366 , 2954 , 1733 , 1576 , 1038 , 933 , 776 , 
 699 cm . hrms ( ci ) m / z calcd for c23h23bno2 [ m + h ] 356.1822 , found 356.1829 .
h nmr ( 500 mhz , acetone - d6 )  9.10 ( br s , 1h ) , 7.82 ( s , 1h ) , 7.637.61 
 ( m , 1h ) , 7.407.35 ( m , 3h ) , 7.127.10 ( m , 1h ) , 6.966.94 
 ( m , 1h ) , 6.72 ( s , 1h ) , 6.53 ( s , 1h ) , 6.526.50 ( m , 2h ) , 3.85 
 ( s , 3h ) , 3.43 ( s , 3h ) , 2.16 ( s , 3h ) , 0.21 ( s , 3h ) .
c 
 nmr ( 125.8 mhz , acetone - d6 )  158.9 , 
 158.8 , 145.1 , 143.0 , 141.6 , 140.2 , 138.2 , 132.6 , 130.6 , 128.9 , 127.6 , 
 124.9 , 123.0 , 120.3 , 117.4 , 115.0 , 112.9 , 112.5 , 111.8 , 54.6 , 54.0 , 
 20.6 .
ir ( neat ) 3390 , 3052 , 2932 , 1595 , 1451 , 1164 , 
 758 cm .
hrms ( esi ) m / z calcd for c24h25bno2 [ m 
 + h ] 370.1978 , found 370.1960 . obtained as a white solid ( 126 mg , 84% ) . 

h nmr ( 500 mhz , acetone - d6 )  9.49 ( br s , 1h ) , 8.04 ( s , 1h ) , 7.95 
 ( s , 1h ) , 7.787.78 ( m , 1h ) , 7.687.66 ( m , 1h ) , 7.587.56 
 ( m , 1h ) , 7.537.51 ( m , 2h ) , 7.477.45 ( m , 2h ) , 7.437.40 
 ( m , 2h ) , 7.307.27 ( m , 1h ) , 0.81 ( s , 3h ) .
c nmr 
 ( 125.8 mhz , acetone - d6 )  144.9 , 
 142.0 , 141.2 , 139.6 , 128.5 , 128.1 , 128.0 , 126.5 , 126.4 , 126.2 , 126.1 , 
 125.8 , 125.2 , 119.1 , 118.0 .
ir ( neat ) 3366 , 3058 , 2931 , 
 1596 , 1450 , 1220 , 750 , 700 cm . hrms ( ci ) m / z calcd for c19h16bns [ m ] 301.1097 , found 301.1099 .
h nmr ( 500 mhz , acetone - d6 )  
 9.50 ( br s , 1h ) , 8.01 ( s , 1h ) , 7.947.92 ( m , 2h ) , 7.687.66 
 ( m , 2h ) , 7.63 ( s , 1h ) , 7.517.48 ( m , 1h ) , 7.477.44 
 ( m , 2h ) , 7.427.38 ( m , 2h ) , 7.307.27 ( m , 1h ) , 0.79 
 ( s , 3h ) .
c nmr ( 125.8 mhz , acetone - d6 )  144.9 , 143.8 , 141.0 , 139.4 , 138.2 , 128.0 , 128.0 , 
 126.3 , 125.9 , 125.9 , 125.8 , 125.2 , 125.0 , 118.0 , 108.6 .
ir ( neat ) 3366 , 3058 , 2929 , 1596 , 1450 , 1220 , 1163 , 750 , 760 
 cm . hrms ( ci ) m / z calcd for c19h16bno [ m ] 285.1325 , 
 found 285.1318 .
the 
 geometries were optimized at the b3lyp/6 - 311g(d ) level , and molecular 
 orbitals and molecular energies were calculated at the same level .
 despite 
 their potential applications in both medicinal chemistry 
 and materials science , there have been limited reports on the functionalization 
 of 2,1-borazaronaphthalenes since their discovery in 1959 . to access 
 new chemical space and build molecular complexity , the suzuki  
 miyaura 
 cross - coupling of brominated 2,1-borazaronaphthalenes has been investigated . 
 the palladium - catalyzed cross - coupling proceeds with an array of potassium 
 ( hetero)aryltrifluoroborates in high yield with low catalyst loadings 
 under mild reaction conditions . 
 by the use of a high - yielding bromination 
 of various 2,1-borazaronaphthalenes to generate electrophilic azaborine 
 species , a library of 3-(hetero)aryl and 3,6-diaryl-2,1-borazaronaphthalenes 
 has been synthesized . 
Introduction
Results and Discussion
Conclusions
Experimental
Section