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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.

A highly efficient and selective synthesis of (1E)- or (1Z)-1,2-dihalo-1,4-dienes viaPd-catalyzed coupling of haloalkynes and allylic halides is described. The (1E)-1,2-dihalo-1,4-dienes were generated in good yields with excellent stereoselectivities (1E/1Zup to >98/2), while (1Z)-1,2-dihalo-1,4-dienes were produced in excellent yields and stereoselectivities (1Z/1Eup to >98/2) by simply adding stoichiometric lithium halides. [ABSTRACT FROM AUTHOR]