Asymmetric transfer hydrogenation using recoverable ruthenium catalyst immobilized into magnetic mesoporous silica

Ru-TsDPEN (TsDPEN=N-(p-toluenesulfonyl)-1,2-diphenylethylenediamine) derived catalyst was firstly immobilized in the magnetic siliceous mesocellular foam material. This heterogeneous catalyst afforded high catalytic activities and ee values in the asymmetric transfer hydrogenation of imine in HCOOH-Et3N system and aromatic ketones in aqueous HCOONa. Furthermore, this heterogeneous catalyst showed an excellent durability and can be reused conveniently by external magnet for at least nine times without noticeable loss of ee values. (C) 2008 Published by Elsevier B.V.