Heterogeneous asymmetric hydrogenation of aromatic ketones enhanced by silanols on highly monodispersed silica spheres

A triphenylphosphine-stabilized Ir/SiO2 catalyst modified by a chiral diamine was synthesized with four silica spheres as support for the asymmetric hydrogenation of aromatic ketones. The H-bond between substrate and silanols and the interaction between substrate and modifier commonly affected the steric configuration of asymmetric hydrogenation of aromatic ketones. With the silanols increasing, the activity of asymmetric hydrogenation significantly increased. This is the first report of heterogeneous asymmetric hydrogenation of aromatic ketones enhanced by silanols on highly monodispersed silica spheres with >99.9% ee and >99% conversion. (C) 2014 Elsevier B.V. All rights reserved.