Visible‐Light Induced Trifluoromethylation/Cyclization of Unactivated Alkene‐Bound Quinazolinones

Abstract

Herein, we reported a selective, mild method for the visible light‐photocatalyzed trifluoromethylation and cyclization of unactivated tethered alkenes to provide tri‐ and tetracyclic quinazolinones. Trifluoroacetic acid and anhydride are inexpensive and readily available reagents for the process which proceeds without the addition of a strong oxidant. Broad substrate scope and the formation of 5‐ and 6‐membered rings are demonstrated in 44‐82% yields. Control experiments provide the basis for a proposed mechanism involving photocatalyzed SET from fac‐Ir(ppy)3 to TFAA, and trifluoromethyl radical‐mediated regioselective cyclization. The practicality of the protocol was illustrated by a gram‐scale synthesis in 76% yield.