Enyne synthesis through a modified Sonogashira cross-coupling reaction catalyzed by cyclopalladated complexes

A series of conjugated enynes were successfully synthesized by the palladacycle-catalyzed modified Sonogashira cross-coupling reaction of β-bromostyrene and terminal alkynes. The reaction proceeds smoothly in DMSO at 40 °C to give the corresponding products in moderate to excellent yields. This catalytic system is tolerant to a broad range of functional groups on the substrates. Moreover, the products were furnished as specific E isomers. We also found that the product of the reaction between (E)-β-bromostyrene and 2-methyl-3-butyn-2-ol is diarylated enyne in the presence of excess Cs2CO3.