Ru-Hydrogenation of Bulky Ketones with a Tridentate Ligand

摘要

Current asymmetric hydrogena-tion catalysts for ketones typically involve[RuCl_2(diphos)(diamine)] systems, related to earli-er catalysts developed by Noyori. While highly ef-fective for most substrate classes, severe limita-tions are encountered with sterically encumberedketones. To overcome this problem, the authorshave synthesized complex 1, possessing a triden-tate P^N^NH_2-type ligand which is thought toprovide a more open coordination environment.With this system, various bulky ketone substratesare reduced in excellent yields and moderate tohigh enantioselectivities under hydrogenation ortransfer hydrogenation parameters.