An Exceptionally Simple Chemical Synthesis ofO‐Glycosylatedd‐Glucosamine Derivatives by Heyns Rearrangement of the CorrespondingO‐Glycosyl Fructoses

Abstract

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.

The design and synthesis of an α-Gal trisaccharide epitope that provides a highly specific anti-Gal immune response

“…The starting material N -acetyllactosamine 18 was prepared using the method of Wrodnigg et al 28,29 Peracetylation of 18 followed by reaction with TMSOTf gave the oxazoline intermediate 20 , which was then coupled to azido-ethanol, 2-(2-azidoethoxy)ethanol or 2-[2-(2-azidoethoxy)ethoxy]ethanol under acidic conditions to yield compounds 21 − 23 (Scheme 2). 30 Subsequent deacetylation followed by α1,3GalT-mediated appendage of galactose gave the α(1,3)-linked trisaccharides 24 and 25 .…”

The Amadori rearrangement as glycoconjugation method: Synthesis of non-natural C-glycosyl type glycoconjugates

“…This indicates that the Amadori rearrangement is a valuable tool in the repertoire of ligation methods, with the advantage that no protecting-group manipulations are necessary in the carbohydrate moiety and the reaction can be carried out in aqueous environment offering obvious advantages in glycobiology. In preliminary studies, several disaccharidic structures, such as cellobiose, lactose and N -DTPM-2-aminodeoxylactose [33], were successfully converted to the respective C -glycosyl type glycoconjugates by this method. Optimisation of yields is currently under progress [34].…”