Chemoselective catalytic reduction of conjugated α,β-unsaturated ketones to saturated ketones via a hydroboration/protodeboronation strategy

A novel copper-catalyzed chemoselective reduction of a carbon-carbon double or triple bond to a carbon-carbon single bond in alpha,beta-unsaturated ketones is developed. This reaction proceeds under hydrogen gas or stoichiometric metal hydride free conditions. Saturated ketones were obtained in good to excellent yields with a broad substrate scope. Mechanistic studies reveal that the two hydrogen atoms come from H2O in the system. Thus this reaction represents a highly efficient, and remarkably chemo-selective strategy.