Metal-Free Indole-Phenacyl Bromide Cyclization: A Regioselective Synthesis of 3,5-Diarylcarbazoles

J Org Chem. 2020 Oct 16;85(20):13272-13279. doi: 10.1021/acs.joc.0c01670. Epub 2020 Oct 2.

Abstract

A metal-free, simultaneous triple C-C coupling cyclization reaction between phenacyl bromides and indoles is discovered in a highly regioselective fashion to furnish 3,5-diarylcarbazoles. DMAP is utilized as the only reagent for the unusual and rapid cyclization reaction to furnish all new carbazole compounds through installation of a great diversity of substituents. A plausible radical mechanism for the new reaction is predicted by conducting various control experiments, competitive reactions, furoindole formation, and ESI-MS analyses of the ongoing cyclization reaction.