Chiral vanadyl salen catalyst immobilized on mesoporous silica as support for asymmetric oxidation of sulfides to sulfoxides

Abstract

cThe chiral vanadyl salen complexwas immobilized intomesoporous silica by a covalent graftingmethod using 3-aminopropyltriethoxysilane as a reactive surface modifier. The formation and integrity of the complex have been confirmed by FT-IR, UV-vis and BET measurements and the complex was tested in the asymmetric oxidation of sulfide to sulfoxide using H2O2 as oxidant. The immobilized complex showed better catalytic activity than the neat complex, while the neat complex has deactivated in the reaction. The combination of the heterogenized catalyst, H2O2 and CH2Cl2 as solvent offers a selective catalytic system for oxidation of sulfide to sulfoxide with a low but significant enantioselectivity in the range of 8-10% ee. In addition, the heterogenized catalyst could be easily separated from the products and reused. © The Author(s) 2010.