1,3,2-Benzimidazaborole, 1,3,2-benzoxaborole, and 1,3,2-benzothiazaborole were synthesized from the corresponding 2-benzazole N-BH3 and 2-benzazole S-BH3 adducts through a reductive transposition from the isolobal fragment X-C(sp2) = N(sp2) - B(sp3) (X = N, O, S) to the fragment X-B(sp2) = N(sp2) - C(sp3). N-BH3 substitution shifts to lower frequencies 4-H, C-3a, and C-7a resonances. The X-ray diffraction analysis of 2-(o-methoxyphenyl)benzothiazole N-BH3 adduct is reported. Two new tetracyclic boron-bridged compounds were observed as by-products (6,9-(ethyl)-diaza-2-oxa-1-bora[3,4,7,8]-dibenzobycyclo[4.3.0]-nona-3,7-diene, 6d, and 8-aza-9-oxa-2-thia-1-bora-[3,4,7,8]dibenzobycyclo[3.4.0]nona-3,7-diene, 15d, when 2-(o-methoxyphenyl)-1-ethylbenzimidazole-BH3 6b and 2-(o-methoxyphenyl)-benzothiazole-BH3 15b adducts were heated.
|Number of pages||13|
|State||Published - 1 Jan 1996|