Palladium-catalyzed direct alkynylation of N-vinylacetamides

A direct ethynylation reaction between N-vinylacetamides and (bromoethynyl)triisopropylsilane catalyzed by palladium is reported. A broad scope of cyclic N-vinylacetamide derivatives was tolerated and the corresponding products could be obtained in acceptable yields. This work provides a general tool for the synthesis of conjugated enyne products using palladium(II) acetate as catalyst. The mild reaction conditions and reasonable results should make this method a useful synthetic protocol. Unfortunately, other bromo-substituted alkynes are found to be unreactive and could not afford the desired products under the current reaction conditions.