Efficient Synthesis of 2-OH Thioglycosides from Glycals Based on the Reduction of Aryl Disulfides by NaBH 4 .

An improved method to efficiently synthesize 2-OH thioaryl glycosides starting from corresponding per-protected glycals was developed, where 1,2-anhydro sugars were prepared by the oxidation of glycals with oxone, followed by reaction of crude crystalline 1,2-anhydro sugars with NaBH 4 and aryl disulfides. This method has been further used in a one-pot reaction to synthesize glycosyl donors having both "armed" and "NGP (neighboring group participation)" effects.