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Free keywords:
O-glycoside synthesis; LiClO4 solvent mixtures; glycosyl phosphates; glycosyl fluorides; glycosyl imidates;
Abstract:
O-Glycosides of pivaloyl-protected glucose can be synthesized under neutral conditions in moderate yields by employing the pivaloylated beta-glucosyl fluoride 2d and the respective beta-benzyl phosphate 2e as glycosyl donors and 1 M solutions of LiClO4 in CH2Cl2 or CHCl3 as reaction media, acetyl-protected alpha- or beta-configured glucosyl trichloroacetimidates la and Ib were converted into the orthoesters 6 which were isolated in moderate to high yields. Under these conditions, acetyl-protected glycosyl phosphates, acetyl- or pivaloyl-protected glycosyl bromides and O-pivaloylated glycosyl trichloroacetimidates were not converted to the desired O-glycosides.
