Transition Metal‐Free Synthesis of Sulfonyl‐ and Bromo‐Substituted Indolo[2,1‐α]isoquinoline Derivatives through Electrochemical Radical Cascade Cyclization

Abstract A tunable electrosynthesis of sulfonyl‐ and bromo‐substituted indolo[2,1‐ α ]isoquinoline derivatives has been disclosed. In this reaction, a variety of easily available 2‐aryl‐ N ‐acryloyl indoles can readily react with sulfonyl and/or bromine radicals, which are generated from arylsulfonyl hydrazides and potassium bromide respectively, to furnish the valuable sulfonyl‐ and bromo‐substituted benzindolo‐fused polycyclic compounds in moderate to good yields. Control experiment indicated that the reaction proceeds via a radical cascade cyclization pathway. This protocol features broad substrate scope and good functional group tolerance under transition metal‐free and oxidant‐free conditions. magnified image