Nickel-catalyzed thioallylation of alkynes with allyl phenyl sulfides.

Allylic sulfides add to alkynes in the presence of nickel complexes efficiently to afford thio-1,4-dienes regio- and stereoselectively. Functional groups such as alkoxy, siloxy, hydroxy, carboalkoxy, chloro, and cyano groups are tolerated. A mechanism that involves a pi-allyl nickel intermediate is proposed on the basis of isolation of pi-allyl complexes and distribution of products in the reactions of alpha- or gamma-methylated allyl sulfide. [reaction: see text].