An efficient and selective palladium-catalysed oxidative dicarbonylation of alkynes to alkyl- or aryl-maleic esters

Terminal alkyne dicarbonylation can be readily effected under mild conditions by treating alkynes with carbon monoxide and alcohols or water at 25–80 °C in the presence of Pdl2, KI and air, with unprecedented catalytic efficiency. Dicarbonylated products are mainly maleic esters or acids and their ring-chain tautomers. The latter are formed to a large extent at room temperature. Reaction pathways are discussed.