Synthesis of tetrasaccharide related to the repeating unit of the O-antigen from Shigella boydii type 5 in the form of its tert-butyl ester and 2-(trimethylsilyl)ethyl glycoside

摘要

Starting from D-mannose,D-glucose and L-rhamnose,two disaccharide blocks ethyl 2,3,4-tri-O-benzyl-alpha-L-rhamnopyranosyl-( 1->3)-2-0-benzy 1-4,6-O-benzy lidene-1 -thio-alpha-D-mannopyranoside and tert-buty 1 2-O-benzy 1-4,6-O-benzylidene-beta-D-mannopyranosyl-(l->4)-[2-(trimethylsilyl)ethyl 2,3-di-O-benzyl-beta-D-glucopyranosid]uronate have been synthesized.Schmidt's inverse addition technique of trichloroacetimidate is utilized for the construction of a disaccharide with a beta-mannosidic linkage in good yield.Coupling of this two disaccharides give the desired tetrasaccharide derivative,tert-butyl 2,3,4-tri-O-benzyl-alpha-L-rhamnopyranosyl-(l->3)-2-O-benzyl-4,6-O-benzylidene-beta-D-mannopyranosyl-(1->3)-2-O-benzyl-4,6-O-benzylidene-beta-D-mannopyranosyl-(l->4)-[2-(trimethylsilyl)ethyl 2,3-di-O-benzyl-beta-D-glucopyranosid]-uronate,which is related to the repeating unit of Shigella boydii type 5.The tetrasaccharide can be coupled with a suitable protein for the preparation of a synthetic vaccine.