Enantioselective hydrogenation of alpha-aryloxy alpha,beta-unsaturated acids. Asymmetric synthesis of alpha-aryloxycarboxylic acids

reaction: see text] A facile preparation of chiral alpha-aryloxy carboxylic acids via asymmetric hydrogenation of the corresponding unsaturated acids has been discovered. A number of catalysts have been identified that give high product enantioselectivity, and the scope of the reaction has been examined with respect to substitution on the aromatic ring and olefin.