| Abstract
| - Activation of ester-protected glycosyl trichloroacetimidatedonors by perchloric acid immobilized on silica afforded 1,2-trans disaccharides in 60−90% yields. Applying this approach to one-pot sequential glycosylation resulted in efficient syntheses of the N-linked glycan trimannoside and LeXand LeA trisaccharides in very good yield (76%, 62%, and59% yields, respectively). Solution phase reactions were alsotranslated to a solid phase format; priming the top of astandard silica chromatography column with perchloric acidimmobilized on silica facilitated “on-column” glycosylationwith subsequent “in situ” purification of products. Couplingyields from this approach were comparable to those obtainedfrom the corresponding solution-phase disaccharide couplings. A series of glycosylated amino acids were alsosynthesized in high yield with use of the on-column approach.
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