Two convenient methods for the one-pot synthesis of chloroacetyl and S-acetylmercaptoacetyl N-glycosides from glycosyl azides have been developed. Both methods involve a mild reduction of the azido group using n-Bu3-P and 1,3-propanedithiol as reducing reagents, respectively.
A conceptually novel strategy has been developed for the synthesis of N-(β-glycosyl)asparagine precursors in good yield by the alkylation of ethylnitroacetateusing six per-O-acetylated N-(β-glycosyl)iodoacetamides derived from mono- and disaccharides. The use of a chiral organocatalyst, N-(9-anthracenylmethyl)cinchoninium chloride (10 mol %), resulted in diastereoselective alkylation up to 64% de
A method for the chemoselective reduction of glycopyranosyl azides using SnCl4 and tin metal as the reducing agent followed by in situ chloroacetylation of the synthesized glycopyranosyl amine was developed. This reaction is applicable to diversely functionalized glycopyranosyl azides for the synthesis of glycopyranosyl chloroacetamides. (C) 2013 Elsevier Ltd. All rights reserved.
Synthesis of ClusterN-Glycosides Based on aβ-Cyclodextrin Core
作者:Juan J. García-López、Francisco Santoyo-González、Antonio Vargas-Berenguel、Juan J. Giménez-Martínez
A convenient method for the synthesis of beta-D-gluco-, beta-D-galacto-, 2-acetamido-2-deoxy-beta-D-gluco- and alpha-D-mannopyranosylamine clusters based on cyclomaltoheptaose (beta-cyclodextrin) is presented. The synthesis involves: 1) the one-pot synthesis of the acetylated chloroacetyl N-glycoside derivatives of D-glucose, D-galactose, 2-acetamido-2-deoxy-D-glucose and D-mannose from the corresponding glycosyl azides, 2) conversion of the chloroacetyl N-glycosides into their isothiouronium derivatives, then 3) attachment of the N-glycosides onto heptakis(6-deoxy-6-iodo) and heptakis(6-chloroacetamido-6-deoxy) beta-cyclodextrin by means of nucleophilic displacement with caesiurn carbonate in dimethylformamide, and 4) de-O-acetylation of beta-cyclodextrin derivatives. The chloroacetyl N-glycoside derivatives were easily prepared by mild reduction of the azide function by one of two methods: a) by the Staudinger reaction, with nBu(3)P, and b) with 1,3-propanedithiol, as reducing reagents.