Electrochemical Dearomative Halocyclization of Tryptamine and Tryptophol Derivatives

A Summary of main observation and conclusion Owing to the easy functionalization of 3-haloindolines to many biologically active compounds, extensive efforts have been made for their efficient preparation. Herein, an electrochemical dearomative bromo- and chloro-cyclization of tryptamine and tryptophol derivatives has been developed under undivided electrolytic conditions. In this protocol, neither external chemical oxidants nor harsh conditions are needed, and a wide range of substituted hexahydropyrroloindolines/tetrahydrofuroindolines are obtained with halide ion in high efficiencies. Moreover, this electrolysis could also be scaled up to gram synthesis with good yields.