Synthesis of Benzimidazole-Fused Triazepines, Triazocines, and Triazonines

Significance

The current report details the synthesis of several seven-, eight-, and nine-membered ring heterocycles by reaction of 2-(ω-amino­alkyl)benzimidazoles with tetrachloro-2-azabuta-1,3-dienes yielding benzimidazole-fused 1,3,5-triazepine, -triazocine, and -triazonine derivatives in excellent yields. The reaction occurs with complete regioselectivity, taking advantage of the higher electrophilicity of C-1 of the azadiene. X-ray crystal structures are given for two products.