Ruthenium-Catalyzed Selective Addition of Carboxylic Acids to Alkynes.A Novel Synthesis of Enol Esters

Article abstract of DOI:10.1021/jo00387a024

Carboxylic acids react with alkynes in the presence of a catalytic amount of bis(ν⁵-cyclooctadienyl)ruthenium/trialkylphosphine/maleic anhydride in toluene at 60-80 deg.C to give enol esters having a terminal methylene group in good to excellent yields with high regioselectivity.The deuterium distributions in the products of the reaction of acetic acid-d with 1-hexyne and ethyl propargyl carbonate were examined.Kinetic measurments revealed that the rate has first-order dependence on carboxylic acid, alkyne, and the initial concentration of the ruthenium catalyst.