Diversity Oriented Synthesis of Indoloazepinobenzimidazole and Benzimidazotriazolobenzodiazepine from N1-Alkyne-1,2-diamines

A one‐pot protocol for the diversity oriented synthesis of two N‐polyheterocycles indoloazepinobenzimidazole and benzimidazotriazolobenzodiazepine from a common N1‐alkyne‐1,2‐diamine building block is described. The approach involves sequential formation of benzimidazole through cyclocondensation and oxidation, which is followed by the formation of either an azepine ring (through alkyne activation and 6‐endo‐dig cyclization, 1,2‐migration with ring expansion, and re‐aromatization), or diazepine and triazole rings through 1,3‐dipolar cycloaddition. Diversity in synthesis: The synthesis of two sets of N‐polyheterocycles was accomplished by using a common bifunctional substrate derived from an alkyne (see scheme). The latter was successfully condensed with two different reactants each having two reactive centers under different catalytic conditions to afford benzimidazole‐based annulated polyheterocycles.