Synthesis of (Z)-β-Chloro-enamides via a Base-Promoted trans-Hydroamidation of Alkynyl Chlorides Using 1,1-Dichloroalkenes as Precursor

An efficient and general base-promoted reaction of 1,1-dichloroalkenes with secondary sulfonamides and amides for the synthesis of (Z)-β-chloro-enamides has been described. This reaction exhibits functional group tolerance under simple and mild conditions. Mechanistic study indicated that a stereoselective trans-hydroamidation of alkynyl chlorides generated in situ from 1,1-dichloroalkenes was the key step.