Visible-light-promoted defluorinative ring-opening gem-difluoroallylation of cycloalkanols using 1-trifluoromethyl alkenes

Abstract

Herein, we describe a photocatalytic defluorinative ring-opening gem-difluoroallylation of cycloalkanols for the synthesis of gem-difluoroalkenes bearing a distal carbonyl group. The reaction proceeds with the generation of alkoxy radicals via a photoredox-enabled proton-coupled electron transfer process. Subsequently, alkoxyl radical-triggered C–C bond cleavage, followed by defluorinative coupling of the resulting remote carbonyl-containing alkyl radicals with 1-trifluoromethyl alkenes, provides the gem-difluoroalkene products in a redox-neutral radical polar crossover manifold. The synthetic applications of the resulting products were demonstrated by intramolecular S_NV reactions via O- or C-cyclization of enolate intermediates, cyclopropanation and fluoro-hydroxylation.