Reductive Dephthalimidation: A Mild and Efficient Method for The N-Phthaumido Deprotection During Ougosaccharide Synthesis |
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Authors: | Falguni Dasgupta Per J. Garegg |
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Affiliation: | Department of Organic Chemistry, Arrhenius Laboratory , University of Stockholm , S-106 91, Stockholm, Sweden |
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Abstract: | Abstract Synthesis of biologically active oligosaccharides, haptens and their protein conjugates is a major area of interest because of their role in antigen-antibody interaction and receptor effects1. A number of these molecules contain α-or β-linked 2-acetamido-2-deoxy-D-glucosamine (GlcNAc) moieties. Most commonly, during the oligosaccharide synthesis, introduction of the β-glycosidically linked GlcNAc residue is achieved by either the oxazoline2 or the phthalimido method3. Of these, the latter is preferred because 2-N-phthalimido protected glycosamine units having a halogen or a thioalkyl group at C-1 have consistently proved to be more efficient donors than are the oxazolines. However, time and again, subsequent conversion of the N-phthalimido to amine by hydrazinolysis has proved inadequate. This has often resulted in a poor overall yield after an otherwise efficient synthesis. Recently it was shown that the phthalimido function could be removed under mild conditions from a number of amino acids4. We now report that this technique can be efficiently used for the deprotection of the phthalimido function in suitably protected carbohydrate compounds (2,3 and 5). |
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