Prearranged Glycosides, Part 10. Intramolecular Glycosylation with Cellobiosyl, Lactosyl, and Maltosyl Donors
摘要:
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-alpha-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 alpha-(1-->)-linked trisaccharides 9. No influence of the donor moiety on the diastereoselectivity of the intramolecular glycosylation was observed.
Prearranged Glycosides, Part 10. Intramolecular Glycosylation with Cellobiosyl, Lactosyl, and Maltosyl Donors
摘要:
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-alpha-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 alpha-(1-->)-linked trisaccharides 9. No influence of the donor moiety on the diastereoselectivity of the intramolecular glycosylation was observed.
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-alpha-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 alpha-(1-->)-linked trisaccharides 9. No influence of the donor moiety on the diastereoselectivity of the intramolecular glycosylation was observed.