Prearranged Glycosides,Part 10. Intramolecular Glycosylation with Cellobiosyl,Lactosyl, and Maltosyl Donors |
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Authors: | Gregor Lemanski Thorsten Lindenberg Hassan Fakhrnabavi Thomas Ziegler |
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Affiliation: | 1. Department of Biomolecular Structure , Glaxo Research and Development Ltd., Glaxo Wellcome Medicines Research Centre , Gunnels Wood Road, Stevenage, Herts SG1 2NY, UK;2. Glycobiology Research Group, Glaxo Research and Development Ltd., Glaxo Wellcome Medicines Research Centre , Gunnels Wood Road, Stevenage, Herts SG1 2NY, UK |
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Abstract: | ABSTRACT Acetyl protected 1,2-O-(1-methoxyethylidene)-disaccharides 1 of maltose, cellobiose, and lactose, respectively were converted via the corresponding benzyl protected couterparts 2, the benzyl protected phenyl 2-O-acetyl- 3 and 2-O-unprotected 1-thio-glycoside disaccharides 4 into 2-O-succinoylated disaccharides 5. The latter were esterified with benzyl 2-O-benzoyl-4,6-di-O-benzylidene-α-D-glucopyranoside (6) to afford succinyl linked derivatives 7 the benzylidene groups of which were regioselectively opened to give prearranged glycoside trisaccharides 8. Intramolecular glycosylation of the latter with N-iodosuccinimide resulted in exclusive formation of the corresponding α-(1→4)-linked trisaccharides 9. No influence of the donor moiety on the diastereoselectivity of the intramolecular glycosylation was observed. |
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