Catalytic Domino Reaction of Ketones/Aldehydes with Me3SiCF2Br for the Synthesis of α-Fluoroenones/α-Fluoroenals

A unique domino reaction of enolizable carbonyl compounds with Me3SiCF2Br to construct a-fluoroenones and a-fluoroenals is described to undergo the in situ formation of difluorocarbene and silyl enol ether, difluorocyclopropanation, desilylation, ring-opening, and defluorination sequence. In this tandem reaction, Me3SiCF2Br acts as not only the difluorocarbene source but also the TMS transfer agent as well as internal bromide and fluoride anion catalyst. It allows the transformations to occur smoothly under only a catalytic amount of n-Bu4NBr as initiator.