Synthesis of stereo-defined 1,1,4,4-tetrahalo- and 1,1,4,4-mixed-tetrahalo-1,3-butadienes

Stereo-defined 1,1,4,4-tetrahalo- and 1,1,4,4-mixed-tetrahalo-1,3-butadienes were obtained in excellent yields via desilylation–halogenation of their corresponding 1,4-bis(trimethylsilyl)-1,4-dihalo-1,3-dienes, which could be readily prepared from the zirconocene-mediated high-yield and high-regioselective cyclo-dimerization of 1-trimethylsilyl-1-alkynes followed by halogenation. These poly-functionalized gem-dihalodienes are potentially useful building blocks.