SYNTHESIS OF UNSYMMETRICAL TREHALOSE ANALOGS BY SILVER TRIFLUOROMETHANESULFONATE PROMOTED GLYCOSYLATIONS

The coupling of benzoylated glucosyl bromides with 2,3,4,6-tetra-O-ben zylated gluco, manno or galacto-pyranoses promoted by silver triflate is described, and the compositions of the crude reaction mixtures, det ermined by C-13 NMR spectroscopy, are presented. Unsymmetrical trehalo se derivatives can be synthesized by such couplings. However, the inhe rent formation of dimerization products of the reactants reduces the v ersatility of the reactions. The synthesis of alpha-D-glucopyranosyl a lpha-L-glucopyranoside and alpha-D-glucopyranosyl beta-L-glucopyranosi de is also described.