Why Is Direct Glycosylation with <i>N</i>-Acetylglucosamine Donors Such a Poor Reaction and What Can Be Done about It?
作者:Mikkel H. S. Marqvorsen、Martin J. Pedersen、Michelle R. Rasmussen、Steffan K. Kristensen、Rasmus Dahl-Lassen、Henrik H. Jensen
DOI:10.1021/acs.joc.6b02305
日期:2017.1.6
chemical glycosylation is challenging since direct reactions are low yielding. This issue, generally agreed upon to be caused by an intermediate 1,2-oxazoline, is often bypassed by introducing extra synthetic steps to avoid the presence of the NHAc functional group during glycosylation. The present paper describes new fundamental mechanistic insights into the inherent challenges of performing direct glycosylation
An efficient conversion of N-acetyl-d-glucosamine to N-acetyl-d-galactosamine and derivatives
作者:Jianhao Feng、Chang-Chun Ling
DOI:10.1016/j.carres.2010.09.008
日期:2010.11
2-Acetamido-2-deoxy-D-galactose (D-GalNAc) is an important monosaccharide widely distributed in nature. However, unlike its 4-epimer, the 2-acetamido-2-deoxy-D-glucose (D-GlcNAc), D-GalNAc is very expensive to obtain from commercial sources. Herein we report an efficient transformation that allows for the conversion of D-GlcNAc to a D-GalNAc derivative 7 in three steps and in 58.4-75% overall yields. The process was carried out on a greater than 20-g scale without the need of chromatography. The versatility of compound 7 was demonstrated by the synthesis of several useful monosaccharides and thiodisaccharides containing a D-GalNAc residue. (C) 2010 Elsevier Ltd. All rights reserved.
Use of N-Pivaloyl Imidazole as Protective Reagent for Sugars
作者:Francisco Santoyo-González、Clara Uriel、José A. Calvo-Asín
DOI:10.1055/s-1998-2224
日期:1998.12
A Direct Method for β-Selective Glycosylation with an N-Acetylglucosamine Donor Armed by a 4-O-TBDMS Protecting Group
作者:Hidenori Tanaka、Yu Hamaya、Hiyoshizo Kotsuki
DOI:10.3390/molecules22030429
日期:——
A new direct method for β-selectiveglycosylation with an N-acetylglucosamine (GlcNAc) donor was developed. This substrate, which can be readily prepared from commercially available GlcNAc in two steps, contains a 4-O-tert-butyldimethylsilyl (TBDMS) protecting group as a key component. We found that this functionality could have a favorable effect on the reactivity of the GlcNAc donor. Glycosylation
Formation of β-Configured Thioglycosides of<scp>d</scp>-Glucosamine and<scp>d</scp>-Galactosamine and Synthesis of Protected Human Milk Oligosaccharides
作者:Kamilla Pedersen、Louise G. Christensen、Henrik H. Jensen
DOI:10.1021/acs.joc.3c01267
日期:2023.9.1
on the stereoselective multigram scale preparation of cyclohexyl- and phenyl thioglycosides of 2-azido-2-deoxy-β-d-gluco- and galactopyranosides from d-N-acetylglucosamine using a catalytic and solvent-free method. Two of the prepared building blocks were used as key intermediates for the synthesis of human milk oligosaccharides LNT and LNnT in their protected form.