Mechanism of the palladium-catalyzed intramolecular hydroalkylation of 7-octene-2,4-dione.

Cyclization of (E)-7,8-dideuterio-7-octene-2,4-dione [(E)-1-7,8-d(2)] catalyzed by PdCl(2)(CH(3)CN)(2) (2) formed cis-2-acyl-3,4-dideuteriocyclohexanone (cis-3-3,4-d(2)) in 64% yield as the exclusive isotopomer. This experiment, in conjunction with additional deuterium labeling experiments, was in accord with a mechanism for the conversion of 1 to 3 catalyzed by 2 involving attack of the enol carbon atom on a palladium-complexed olefin followed by palladium migration and protonolysis from a palladium enolate complex.