No abstract

Carbohydrates Carbohydrates U 0500 An Exceptionally Simple Chemical Synthesis of O-Glycosylated D-Glucosamine Derivatives by Heyns Rearrangement of the Corresponding O-GlycosylFructoses. -The tremendous practicability of the Heyns rearrangement is exemplified in the syntheses of two new N-protected derivatives of D-lactosamine (VI) and D-nigerosamine (IX) from the corresponding commercially available glycosylated ketoses, lactulose (I) and turanose (VII), respectively. -(STUETZ, A. E.; DEKANY, G.; EDER, B.; ILLASZEWICZ, C.; WRODNIGG*, T. M.; J.

2-N-Acetyl-4-O-(b-D-galactopyranosyl)-D-glucosamine (N-acetyl-D-lactosamine), a very important building block of biologically relevant oligosaccharides such as sialyl Lewis x , is easily accessible via the Heyns rearrangement of the corresponding Oglycosylated ketohexose, D-lactulose. This approach can also be extended to other glucosamine derivatives employing suitable O-glycosylated ketoses many of which are commercially available. For example, nigerosamine (3-O-a-D-glucopyranosyl-Dglucosamine) was prepared from turanose (3-O-a-D-glucopyranosyl-D-fructose). In combination with a recently introduced vinylogous amide type N-protecting group, [1,3-dimethyl-2, 4, 6 (1H, 3H, 5H)-trioxopyrimidine-5-ylidene] methyl (DTPM), this access is clearly superior to other routes and eminently suitable for scaling up.

A range of partially protected ketoses was O-galactosylated with ␤-galactosidase from Aspergillus oryzae employing (4-nitro)phenyl ␤-D-galactopyranoside as the donor. This enzyme also accepted free D-tagatose as a substrate.

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