Epoxidation of glycals with oxone–acetone–tetrabutylammonium hydrogen sulfate: a convenient access to simple β- d-glycosides and to α- d-mannosamine and d-talosamine donors

Abstract

The addition of a phase transfer catalyst during the epoxidation of perbenzylated glycals with oxone–acetone under biphasic conditions allows their complete epoxidation. The epoxides were readily transformed into methyl 1,2- trans-β- d-glycosides or 1,2- trans-β- d-glycopyranosyl azides ( d- gluco and- d- galacto configurations) bearing a free hydroxyl group at the 2-position. These glycosyl azides were converted to alkyl 1,2- trans-2-acetamido-2-deoxy-α- d-pyranosides or alkyl 2-allyloxycarbonylamino-2-deoxy-α- d-pyranosides ( d- manno and d- talo configurations) by a Staudinger reaction and a double inversion of configuration at C-1 and C-2.