Rhenium-Catalyzed Regio- and Stereoselective Synthesis of γ-Thio-α,β-unsaturated Ketones via Insertion of Terminal Alkynes into the C-S Bond

The reaction of alpha-thioketones and alkynes in the presence of a rhenium catalyst, [HRe(CO)(4)](n), gave gamma-thio-alpha,beta-unsaturated ketones in excellent yields. The alkynes were inserted into the carbon-sulfur bond of the alpha-thioketones, and isomerization of a double bond provided the products with high regio- and stereoselectivities. This reaction also proceeded in an intramolecular fashion.