Hydrogenation of Hindered Ketones Catalyzed by a Silica-Supported Compact Phosphine−Rh System

A heterogeneous mono(phosphine)−Rh catalyst system silica-SMAP−Rh(OMe)(cod), where silica-SMAP stands for a caged, compact trialkylphosphine (SMAP) supported on silica gel, showed broad applicability toward the hydrogenation of hindered ketones. Doubly α-branched ketones such as diisopropyl ketone was hydrogenated under nearly atmospheric conditions. Di-tert-butyl ketone could be hydrogenated under more forcing conditions.