Activation of bis(trimethylsilyl) peroxide and tert-butyl hydroperoxide with oxo and peroxo complexes of vanadium, molybdenum, and tungsten for the sulfoxidation of thianthrene 5-oxide

Bis(trimethylsilyl) peroxide (BTSP) and tert-butyl hydroperoxide (tBuODH) were activated by various oxo and peroxo complexes of molybdenum, tungsten, and vanadium as catalysts for the sulfoxidation of thianthrene 5-oxide (SSO). A screening of a number of phosphane oxide and amine oxide ligands revealed that BTSP was most efficiently activated by the [MoO5(OPtBu(3))] complex. The best results for tBuOOH as oxygen source were achieved with the vanadates [VO(OR)(3)] (R=tBu, iPr). Comparative selectivity and rate data for the stoichiometric and catalytic sulfoxidations of SSO mediated by the MoO(5)L complex (L=OPtBu(3), OPnOct(3), ONnBu(3), ONnOct(3)) suggest that the bisperoxo metal complex is the active oxygen transfer species.