Photochemical Radical Bicyclization of 1,5-Enynes: Divergent Synthesis of Fluorenes and Azepinones

Org Lett. 2024 Jan 26;26(3):757-762. doi: 10.1021/acs.orglett.3c04246. Epub 2024 Jan 17.

Abstract

A dual nickel- and iridium-photocatalyzed radical cascade bicyclization reaction for the synthesis of highly complex molecular structures in an atom- and step-economic manner has been described. A series of radical precursors are utilized for the divergent synthesis of diversely substituted fluorenes and indenoazepinones bearing quaternary carbons by using cascade cyclization reactions of 1,5-enynes. This reaction is characterized by its mild conditions, broad substrate scope, excellent selectivity, and satisfactory yield including facile scale-up synthesis.