ABSTRACT
Highly chemoselective catalytic hydrogenation of carbonyl functionality has been developed, using a novel class of catalysts that function with a mechanism-based selectivity for the reduction of polar unsaturation. Using hydrogen as the reductant, these catalysts provide essentially complete selectivity for hydrogenation of ketones, even in the presence of other functionality normally more reactive toward catalytic hydrogenation and hydrogenolysis. In contrast to most homogeneous and heterogeneous hydrogenation catalysts, this system utilizes a base metal, copper, and exploits the unique properties of the copper(I) oxidation state, where standard mechanisms for catalytic hydrogenation do not operate. In this contribution, the optimization of catalyst formulation for the reduction of ketones is discussed, revealing a surprisingly subtle interplay of steric and electronic influences on catalyst structure and function.
