Mechanistic insights into the palladium-induced domino reaction leading to ketones from benzyl beta-ketoesters: first characterization of the enol as an intermediate.

The monitoring by UV spectroscopy of the Pd-catalyzed hydrogenolysis in acetonitrile of 2-methyl-2-benzyloxycarbonyl-1-indanone and 2-methyl-2-benzyloxycarbonyl-1-tetralone showed the successive formation of corresponding beta-ketoacids and enols to deliver finally the ketones. Some factors which influence the stability of the intermediates are determined. In contrast to the above benzyl beta-ketoesters, the enol was not detected from benzyl (2-methylinden-3-yl) carbonate.