Enol Ester Synthesis via Cobalt-Catalyzed Regio- and Stereoselective Addition of Carboxylic Acids to Alkynes.

A cobalt-catalyzed highly regio- and stereoselective hydro-oxycarbonylation of alkynes is reported. Both terminal and internal alkynes can react with carboxylic acids to afford enol esters in high yields. The catalyst generated from Co(BF4)2, tridentate phosphine ligand L5, and zinc in situ exhibits much higher reactivity than the corresponding cobalt/diphosphine complex.