Asymmetric catalytic sulfoxidation by a novel VIV8 cluster catalyst in the presence of serum albumin: a simple and green oxidation system

A novel VIV8 cluster formulated as [V8O12(OH)4(CH3O)4(DAC)4]·7CH3OH (1) (DAC = 1,2-diaminocyclohexane) has been constructed successfully. Enantioselective oxidation of a series of alkyl aryl sulfides catalyzed by 1 is tested in an aqueous medium in the presence of serum albumin. The catalytic procedure is found to be simple and environmentally friendly. The influences of the parameters such as concentration of catalyst and oxidant, pH, and reaction time on the thioanisole as models are investigated. Under optimum conditions, 1 exhibits high conversion (up to 99%), excellent chemoselectivity (≥90% in all cases) and moderate enantioselectivity (up to 75% ee). After binding with serum albumin, the catalytic activity of 1 is promoted. The bovine serum albumin (BSA) and pig serum albumin (PSA) molecules have a more positive effect on the catalytic activity.