Metal-free synthesis of <i>gem</i>-difluorinated heterocycles from enaminones and difluorocarbene precursors

Abstract

A cascade strategy to synthesise <i>gem</i>-difluorinated 2<i>H</i>-furans from reactions of BrCF₂CO₂Et with enaminones has been described. The reactions tolerate a wide variety of functional groups under metal-free conditions. An active aminocyclopropane is proposed to be a key intermediate through the cyclopropanation of difluorocarbene with enaminones, which further triggers a regioselective C-C bond cleavage <i>in situ</i> to afford the corresponding <i>gem</i>-difluorinated 2<i>H</i>-furans.