Highly Chemo- and Enantioselective Hydrogenation of Linear α,β-Unsaturated Ketones

Highly chemo- and enantioselective hydrogenations of linear β,β-disubstituted enones (see scheme) have been accomplished by using iridium complexes 1 a–i bearing chiral sulfoximine-type P,N-ligands. The catalyst system preferentially hydrogenates the CC double bonds giving saturated ketones as the major products. Substrates with bulky substituents at the β-position give the best enantioselectivities. Thus, enones with isopropyl and cyclohexyl substituents afford ketones with 97 % ee (at >95 % conversion).