An efficient and selective method for preparing glycosyl sulfoxides by oxidizing glycosyl sulfides with OXONE or t-BuOOH on SiO2.

Silica gel adsorbed with OXONE or t-BuOOH was used as a mild oxidant to selectively oxidize glycosyl sulfides to corresponding sulfoxides in good yields and without sulfones formation. This method was also found compatible with various other functional groups in the glycosides.