A concise synthesis of indole-fused azepino- and azocino-indoles via acid-catalyzed 1,2-migration

Abstract

A concise and efficient strategy for the synthesis of indole-fused azepino[1,2-a]indoles and the rarely reported azocino[1,2-a]indoles from isatin derivatives is described. The modular sequence combines allyl-metal addition, Grignard-mediated 1,2-allyl migration, ring-closing metathesis, and an acid-catalyzed 1,2-aryl/alkyl migration-aromatization to afford tricyclic frameworks in good to excellent yields under mild conditions.