Chiral dioxomolybdenum(VI) and oxovanadium(V) complexes anchored on modified USY-zeolite and mesoporous MCM-41 as solid selective catalysts for oxidation of sulfides to sulfoxides or sulfones

Heterogenisation of new dioxomolybdenum and oxovanadium complexes bearing a trietoxysilyl group on modified ultra stable Y zeolite and mesoporous all-silica MCM-41 through covalent bonding to support is reported. All catalysts, homogeneous and heterogenised, are active and highly selective in the oxidation of alkyl phenyl sulfides to sulfoxides using TBHP or H2O2 as final oxidants. The corresponding sulfones were obtained in quantitative yield when 2.5 equivalents of oxidant were used. The heterogenised catalysts have shown a comparable activity respect to the corresponding homogeneous ones. Lifetime of heterogenised catalysts has been examined by repeated use of the complexes leading similar rates and yields of sulfoxide, without appreciable loss of metal over several runs, when molybdenum complexes were used as catalysts. (C) 2003 Elsevier B.V. All rights reserved.