Chemical synthesis of β-D-ManNAc containing pentasaccharide repeating unit of the exopolysaccharide from Lactobacillus rhamnosus BIM B-1039 in the form of its p-methoxyphenyl glycoside.

Total synthesis of the pentasaccharide repeating unit of the exopolysaccharide from Lactobacillus rhamnosus BIM B-1039 is accomplished by bis-glycosylation on a suitably protected trisaccharide di-ol. The stereochemically challenging β-D-ManNAc residue was introduced through a glucose derivative to ensure β-selectivity followed by inversion of the 2-OH position with azido group to form the desired mannosamine moiety. The use of the p -methoxyphenyl glycoside at the reducing end was triggered by the fact that its oxidative cleavage followed by the formation of the trichloroacetimidate derivative will open up the scope for further conjugation of suitable aglycon. [Display omitted] • Total chemical synthesis of the tetrasaccharide repeating unit of the O-antigent from Lactobacillus rhamnosus BIM B-1039. • Incorporation of challenging β-D-ManNAc unit in the oligosaccharide. • Potential vaccine designing. [ABSTRACT FROM AUTHOR]