Facile access to gem-difluorocyclopropanes via an N-heterocyclic carbene-catalyzed radical relay/cyclization strategy

Abstract

N-Heterocyclic carbene catalyzed difluorocyclopropanation of alkenes with aldehydes and CF₂Br₂ for a facile and efficacious synthesis of a new class of functionalized gem-difluorocyclopropanes bearing acyl groups has been developed. The reaction involves a cascade three-component radical relay/intramolecular cyclization process. This protocol features metal- and photocatalyst-free reaction conditions, readily accessible starting materials, good functional group tolerance, and easy scalability. Moreover, this strategy is appealing to pharmaceutical chemistry because it is potentially useful in constructing and modifying bioactive molecules via late-stage functionalization.