Regioselective glycosylation of fully unprotected sugars by means of molecular recognition using arylboronic acid

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The methodology is adapted to molecular recognition of sugar structures with arylboronic acids, which from 5-membered boronates from 1,2-cis-dihydroxy groups, or 6-membered boronates from 1,3-dihydroxy groups. As expected glycosylation occurs on the left hydroxy group free from the boronate formation, and then the boronates are removed in situ by aqueous workup to yield various disaccharides in one-pot process.Various hexoses. eg., D-glucose, D-galactose, D-mannose were glycosylated, after boronate formation, with phenyl per-O-benzoyl-1-thio-β-D-glucopyranoside, -β-D-galactopyranoside and -α-D-mannopyranoside in the presence of promoters (NIS-TMSOTf) to furnish corresponding disaccharides ; glycosyl-β(1→6)-D-glucose, -β(1→6)-D-galactose, -βα(1,1)-D-mannoside in good yields.This method would be of significance with respect to regio- and stereoselecyive glycosylation, which might contribute to simple, one-pot preparation of various oligosaccharides of biological interest.