Synthesis of beta-D-Galp-(1 -> 3)-beta-D-Galp-(1 -> 6)-[beta-D-Galf-(1 -> 4)]-D-GlcNAc, a tetrasaccharide component of mucins of Trypanosoma cruzi

摘要

The synthesis of free beta-D-Galp-(1-->3)-beta-D-Galp-(1-->6)-[beta-D-Galf-(1-->4)]-D-G]cNAc and the corresponding alditol which has been previously isolated by reductive beta-elimination of Trypanosoma cruzi glycoproteins are described. A convergent route was envisioned by condensing an acceptor derivative of beta-D-Galf-(1-->4)-D-GlcNAc with a donor derivative of beta-D-Galp-(1-->3)-D-Galp. The trichloroacetimidate method, as well as SnCl4-promoted condensation were utilized for the introduction of the galactofuranosyl unit. On the other hand, the glycosyl-aldonolactone approach, followed by reduction of the lactone with diisoamylborane, and further isomerization to the galactopyranose configuration gave the donor derivative, which was condensed by the trichloroacetimidate method. Moreover, a synthon for the introduction of the beta-D-Galp-(1-->3)-D-Galf unit is described. (C) 2002 Elsevier Science Ltd. All rights reserved. [References: 22]