Cu-catalyzed hydrofluoroacetylation of alkynes or alkynyl carboxylic acids leading highly stereoselectively to fluoroacetylated alkenes

A copper-catalyzed hydrofluoroacetylation of arylacetylenes or alkynyl carboxylic acids with bromofluoro-acetates was developed. The reaction shows excellent stereoselectivity to afford fluoroacetylated alkenes in good to excellent yields with a broad substrate scope. A preliminary mechanism study suggested that a radical pathway was involved in the reaction and (phenylethynyl) copper might be the key intermediate for the reaction. B(2)pin(2) also plays an indispensable role in this novel hydrofluoroacetylation reaction.