Platinum Metals Rev., 2002, 46, (4), 180
Recyclable Ruthenium-BINAP Catalysts
Ryoji Noyori has been involved in asymmetric homogeneous hydrogenation for over thirty years. His work in this important area has resulted in catalysts with high selectivity and wide application (T. J. Colacot, Platinum Metals Rev., 2002, 46, (2), 82–83). Among catalysts he has helped to develop is Ru-BINAP, (BINAP = 2, 2’ bis(diphenylphosphino)-1, 1'-binaphthyl) which, as Ru(II)-BINAP dihalide complexes, provides a versatile general asymmetric hydrogenation of functionalised ketones.
Now, scientists from China have synthesised dendritic Ru-BINAP catalysts that are peripherally alkyl-functionalised (G.-J. Deng, Q.-H. Fan, X.-M. Chen, D.-S. Liu and A. S. C. Chan, Chem. Commun., 2002, (15), 1570-1571). These catalysts can be used for asymmetric hydrogenation in an ethanol/hexane reaction medium. Acids: 2-arylacrylic, 2-phenyl-acrylic and 2-[p -(2-methylpropyl)phenyl]acrylic used for model reactions had high catalytic activity and enantioselectivity. Phase separation was induced by adding a small amount of water. The hexane catalyst-containing layer can be removed for reuse.