Synthesis and crystal structure of 2-(anthracen-9-yl)-1-(tert-butyldimethylsilyl)-3,6-dihydro-1⁴,2⁴-azaborinine

The title compound, C24H30BNSi (I), is an asymmetric 1,2,3,6-tetrahydro-1,2-azaborinine consisting of a BN-substituted cyclohexadiene analog with a B-anthracenyl substituent. A ring-closing metathesis with subsequent substitution of the obtained BCl 1,2-azaborinine using anthracenyl lithium yielded the title compound I. The asymmetric unit (Z = 8) belongs to the orthorhombic space group Pbca and shows an elongated N-C bond compared to previously reported BN-1,4-cyclohexadiene [Abbey et al. (2008) J. Am. Chem. Soc. 130, 7250-7252]. The primarily contributing surface interactions are H center dot center dot center dot H and C center dot center dot center dot H/H center dot center dot center dot C (as elucidated by Hirshfeld surface analysis) which are dominated by van der Waals forces. Moreover, the non-aromatic BN heterocycle and the protecting group exhibit intra- and intermolecular C-H center dot center dot center dot pi interactions, respectively, with the anthracenyl substituent.