Synthesis of cis-1,2-Dihaloalkenes Featuring Palladium-Catalyzed Coupling of Haloalkynes and α,β-Unsaturated Carbonyls.

A highly regio- and stereoselective method for the synthesis of cis-1,2-dihaloalkenes through Pd-catalyzed coupling of haloalkynes and α,β-unsaturated carbonyls has been reported. Excellent stereoselectivities (Z/E up to >98:2) were observed in most cases. This method was subsequently applied to synthesize the functionalized conjugated enyne via the mono-Sonogashira coupling reaction of cis-1-chloro-2-iodoalkene.