Synthesis of chiral 1,2-diamine immobilized on polystyrene and its application to asymmetric hydrogenation of aromatic ketones

A novel chiral 1,2-diamine monomer (S,S)-12 has been synthesized and copolymerized with styrene to give cross-linked polymer. After deprotection of the tert-butoxycarbonyl groups, polymer-supported chiral 1,2-diamine (S,S)-P was obtained. The primary 1,2-diamine moieties on the polymer have been allowed to form the complex with RuCl2/(S)-BINAP. The polymeric chiral complex was used as a catalyst of asymmetric hydrogenation of aromatic ketones to yield the corresponding secondary alcohols in quantitative conversion with high level of enantioselectivity. The polymeric catalyst was recycled several times without any loss of the catalytic activity.