SYNTHESIS OF AZEPINO[1,2-<i>a</i>]BENZIMIDAZOLES AND IMIDAZO[1,2-<i>a</i>]AZEPINES

Abstract

Fusion of 4-bromo-1,3-diphenyl-2-buten-1-ones (γ-bromodypnones) with 1,2-dimethyl-1H-benzimidazole and further treatment of the reaction product with a base (morpholine) gives 7,9-diaryl-5-methyl-5,10-dihydroazepino[1,2-a]benzimidazol-11-ium bromides. The reaction of γ-bromodypnone with 1-alkyl-2-methyl-1H-imidazoles in benzene at 25ºC gives quaternary azolium salts. Upon heating their solutions in alcohol in the presence of K₂CO₃ the latter cyclize to 1-R-6,8-diaryl-1,5-dihydroimidazo[1,2-a]azepin-4-ium bromides or 1-R-6,8-diaryl-1H-imidazo[1,2-a]azepines depending on the nature of the substituent in the benzene rings and the substituent at the N(1) atom of the imidazole.

Authors: L. M. Potikha, A. R. Turelyk, and V. A. Kovtunenko

English translation in Chemistry of Heterocyclic Compounds, 2011, 47 (6), pp 745-754

http://link.springer.com/article/10.1007/s10593-011-0829-6