Revised synthesis of the pentasaccharide related to the repeating unit of the O-antigen from Shigella dysenteriae type-4 in the form of its methyl ester 2-(trimethylsilyl)ethyl glycoside

摘要

A revised and simplified method has been developed for the synthesis of the pentasaccharide,related to the repeating unit of the OMICRON-antigen from Shigella dysenteriae type-4.The disaccharide donor 10 and the trisaccharide acceptor 8 with two hydroxyl groups are first synthesized which are then allowed to react in the presence on NIS and TfOH to give a pentasaccharide derivative from which,removal of protecting groups affords the desired repeating unit,namely methyl alpha-L-fucopyranosyl-(l->3)-2-acetamido-2-deoxy-alpha-D-glucopyranosyl-(l->3)-2-acetamido-2-deoxy-4-OMICRON-(alpha-L-fucopyranosyl)-alpha-D-glucopyranosyl-(l->4)-[2-(trimethylsilyl)ethyl P-D-glucopyranosid] uronate 15.