Synthesis of 1H‐[1,2]diazepino[4,5‐b]indole derivatives

Abstract

AbstractA synthesis of four 1H‐[1,2]diazepino[4,5‐b]indole derivatives and some preliminary information about their biological activity are presented. The starting materials were 2‐ethoxycarbonylindoles and 2‐ethoxy‐carbonyl‐3‐formylindoles, la, b and 2a, b, respectively. 2‐Ethoxycarbonyls la, b reacted with 1‐dimethylamino‐2‐nitroethylene and ‐2‐ethoxycarbonyl‐3‐formylindoles 2a, b in the presence of nitroalkanes (nitromethane or nitroethane) giving 3‐(2‐nitrovinyl)indoles 3a, b. Reduction of 3a, b yielded β‐(2‐oxoalkyl)indoles 4. On reaction with an excess of hydrazine hydrate, compounds 4 gave satisfactory yields of 5‐oxo‐1H‐[1,2]diazepino[4,5‐b]indoles 5.