alkoxycarbonylation

Alkoxycarbonylation is a chemical reaction in which an alkoxycarbonyl group (−COOR) is introduced into a substrate, typically across a carbon–carbon multiple bond, by the simultaneous incorporation of carbon monoxide (CO) and an alcohol. In practice, three components—the unsaturated substrate, CO, and the alcohol—combine in the presence of a transition-metal catalyst to give an alkyl ester.

Most developed variants use transition metals such as palladium, rhodium, cobalt, or nickel with suitable ligands. The reaction conditions usually include a CO atmosphere and a source of the alcohol, with promoters or Lewis acids sometimes employed to improve selectivity. Substrates include simple alkenes, conjugated dienes, and, less commonly, alkynes; products are the corresponding alkyl esters derived from the alcohol used.

Mechanistically, the process generally involves insertion of CO into a metal–alkyl or metal–acyl intermediate, followed by nucleophilic attack of the alcohol and reductive elimination to release the ester and regenerate the active catalyst. The outcome in terms of regioselectivity and stereochemistry depends on the substrate, catalyst, and reaction conditions.

Alkoxycarbonylation provides direct access to esters from inexpensive hydrocarbons and CO, complementing other carbonylation methods such as hydroformylation. It is used in the synthesis of monomers and specialty esters in organic and polymer chemistry, though the need for CO and sensitive catalysts can limit scalability and substrate scope.