Synthesis of β-d-Galf-(1−3)-d-GlcNAc by the Trichloroacetamidate Method and of β-d-Galf-(1−6)-d-GlcNAc by SnCl4-Promoted Glycosylation

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Abstract
In a continuation of our studies on the characterization of the glycoproteins of T. cruzi new galactofuranosyl disaccharides were synthesized. β-d-Galf-(1−3)-d-GlcNAc (1) was prepared by employing the trichloroacetamidate procedure for the glycosylation step. The mild conditions of this reaction are appropriate for condensation of 2,3,5,6-tetra-O-benzoyl-β-d-galactofuranosyl trichloroacetamidate (6) with acid-labile benzyl 2-acetamido-4,6-O-benzylidene-2-deoxy-α-d-glucopyranoside (3). On the other hand, tin(IV) chloride promoted condensation of benzyl 2-acetamido-3-O-benzoyl-2-deoxy-α-d-glucopyranoside (11) with penta-O-benzoyl-α,β-d-galactofuranose (4) gave the derivative of β-d-Galf-(1−6)-d-GlcNAc (2) in 78% yield.