Rhenium-Catalyzed Regio- and Stereoselective Addition of Two Carbon Units to Terminal Alkynes via Carbon–Carbon Bond Cleavage of β-Keto Sulfones

Treatment of β-keto sulfones with terminal alkynes gave unsaturated δ-keto sulfones in good to excellent yields under rhenium catalysis. In this reaction, the insertion of the alkynes into the nonstrained carbon–carbon single bond between the α- and β-positions of the β-keto sulfones proceeded smoothly, and (Z)-isomers were produced with high regio- and stereoselectivities.