Ru(II)-Chiral (1R,2S)-(+)-cis-1-amino-2-indanol immobilized over SBA-15 for asymmetric transfer hydrogenation reaction of prochiral ketones

Mesoporous SBA-15 (Santa Barbara University at California) has been synthesized and functionalized with (4-chloromethyl)phenyltriethoxysilane, there after the surface silanols groups were passivated by dimethoxydimethylsilane (MeO2Me2Si) [Bz-SBA-15]. Further (1R,2S)-(+)-cis-1-amino-2-indanol [AIL] has been immobilized over functionalized SBA-15 (BzAIL-SBA-15). The heterogeneous catalysts were synthesized by complexation of BzAIL-SBA-15 by [RuCl2(benzene)](2) and [RuCl2(p-cymene)](2) in 2-propanol at reflux condition designated as Ru-Bn-BzAIL-SBA-15 (Ru-1) and Ru-Cy-BzAIL-SBA-15 (Ru-2). The synthesized materials have been characterized by small angle X-ray diffraction spectroscopy (SAXS), N-2 adsorption-desorption isotherms, Fourier Transformed-Infra-red (FT-IR) spectroscopy, Transmission Electron Microscopy (TEM), intensively Coupled plasma atomic emission spectroscopy (ICP-AES), Diffuse reflectance UV-vis and C-13 CP MAS NMR analysis. Further the synthesized and characterized materials (Ru-1 and Ru-2) have been successfully applied in the asymmetric transfer hydrogenation (ATH) reaction of simple prochiral ketones, which gave a yield of 56% and 18% and enantiomeric excess (ee) values of 62% and 77% for Ru-1 and Ru-2, respectively, after 1 h for acetophenone. The reusability studies showed approximately the same enantiomeric excess value at lower conversions. (c) 2008 Elsevier B.V. All rights reserved.