Regioselective difluoroallylation of alkylidene malonates with trifluoromethyl alkenes: synthesis of gem-difluoro-1,5-dienes and their [2 + 2] photocycloaddition

Abstract

We herein report a base-controlled α- or γ-difluoroallylation of alkylidene malonates with trifluoromethyl alkenes, providing various gem-difluoro-1,5-dienes with excellent regioselectivity. Upon irradiation with visible light in the presence of fac-Ir(ppy)₃, the intramolecular crossed [2 + 2] photocycloaddition of gem-difluoro-1,5-dienes leads to the formation of highly substituted bicyclo[2.1.1]hexanes in good to excellent yields via an energy transfer pathway.