Highly Selective Photoinduced Dimerization of Alkyl Pyruvates Catalyzed by Cobaloxime

Article abstract of DOI:10.1021/jo00243a022

Alkyl pyruvates with an electron-withdrawing group, an α-methyl group, and a group that can react with hydridocobaloxime were dimerized selectively to dialkyl 4-hydroxy-4-methyl-2-oxopentanedioates in the presence of a catalytic amount of benzyl(pyridine)cobaloxime under irradiation by a tungsten lamp.Hydridocobaloxime is the active species produced by the reaction of photoactivated benzylcobaloxime and alkyl pyruvate in the initiation step.The hydridocobaloxime induced the dimerization reaction catalytically via the insertion of enol pyruvate into the Co-H bond of the hydridocobaloxime to give an intermediate alkylcobaloxime, which, in the catalytic cycle, reacted with the second alkyl pyruvate.