Palladium-Catalyzed Arylthiolation of Alkynes Enabled by Surmounting Competitive Dimerization of Alkynes.

By overcoming the unwanted catalytic dimerization of terminal alkynes, palladium-catalyzed carbothiolation of alkynes with heteroaryl sulfides has been accomplished to provide the corresponding β-heteroaryl alkenyl sulfides with high regio- and stereoselectivity. The key for the preferential arylthiolation is the use of arylsulfanyl segments, instead of alkylsulfanyl, for smooth C(heteroaryl)-SR1 bond cleavage and/or of alkylacetylenes that are reluctant to undergo the dimerization. The reaction proceeds under mild and neutral conditions, with various functionalities being thus tolerated.