Reaction Course Dependent Regiospecific Transformation of 4‐Azido‐Coumarin into Coumarin C3‐C4 Fused Imidazole and 5‐Substituted‐1,4‐Benzodiazepine Scaffolds

Abstract

Herein, we report an efficient route for coumarin C3‐C4 fused imidazole scaffolds via indium chloride‐mediated single‐step transformation of 4‐azido‐coumarin with amines/aldehydes and coumarin C3‐C4 fused 5‐substituted‐1,4‐benzodiazepine scaffolds with 1,2‐azide‐nitrogen migration through two‐step sequential synthesis via the transitory intermediacy of 2,3‐bridged‐2H‐azirine. A plausible mechanistic pathway has been proposed from the control/entrapment experiments and 1H‐NMR studies. This protocol provides the reaction condition‐dependent product selectivity, structural diversification, and excellent yields.