ISSN:
1434-193X
Keywords:
Carbohydrates
;
Cyclitols
;
Carbohydrate mimics
;
Disaccharides, 5a′-carba-
;
5a′-Carbalactoside
;
N-Acetyl-5a′-carbalactosaminide
;
Chemistry
;
General Chemistry
Source:
Wiley InterScience Backfile Collection 1832-2000
Topics:
Chemistry and Pharmacology
Notes:
Construction of the ether-linked methyl 5a′-carba-β-lactoside (3) and N-acetyl-5a′-carba-β-lactosaminide (4) were carried out starting from the coupling products 15 and 16, readily obtained by coupling between 1,2-anhydro-4,6-O-benzylidene-5a-carba-D-mannopyranose (7) and the oxide anions generated from methyl 2,3,6-tri-O-benzyl-β-D-glucopyranoside (8) and methyl 2-acetamido-3,6-di-O-benzyl-2-deoxy-β-D-glucopyranoside (10), respectively. Their 5a-carba-α-D-mannopyranose moieties were transformed into those of 5a-carba-β-D-galactopyranose by a sequence of reaction: Oxidation of the 2′-OH group, epimerization of the C-1′ with DBU, selective reduction of the carbonyl group, and epimerization of the C-4′ via oxidation and then reduction of 4′-OH or SN2 reaction of the 4′-mesylate with an acetate anion. Reaction of 1,2-anhydro-6-O-benzyl-3,4-O-isopropylidene-5a-carba-α-D-galactopyranose (6), initially expected as the potential donor, with these oxide anions did not give any ether-linked products, rather resulting in elimination reaction of 7. However, coupling of the epoxide 6 with methyl 2-acetamido-4-amino-2,4-dideoxy-β-D-glucopyranosides (19) easily gave rise to imino-linked 5a′-carbadisaccharide derivative 38, which, after deprotection, gave the imino-linked congener 5. On the other hand, two biologically interkesting carbadisaccharides including methyl N,N′-diacetyl-5a′-carbachitobioside (45) were obtained from the versatile intermediate 24.
Type of Medium:
Electronic Resource
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