Palladium-catalyzed acyldemetallation and carbonylation reactions of organomercurials for the synthesis of unsymmetrical ketones

Abstract

The palladium-catalyzed acyldemetallation reactions of organomercurials (R 2Hg or AlkHgI) provide a mild, selective, and general method for the synthesis of unsymmetrical heterocyclic ketones. High yields of ketones (RCOR′) were obtained along with small amounts of homocoupling products (R 2). The reaction is accelerated by a nucleophilic catalyst with both organic groups of R 2Hg taking part in the reaction. The selectivity of the reaction towards the ketone can be increased by carrying out the reaction with a suitable combination of reactants under vacuum. The palladium-catalyzed carbonylation of organomercurials in the presence of ArI is another route to unsymmetrical ketones. The AlkHgIArI system undergoes carbonylation in the presence of palladium complex and excess of iodide ion under mild conditions to give high yields of unsymmetrical ketones. The selectivity and rate of the reaction depend upon the nature of the catalyst, solvent, and the concentration of iodide ion.