Block synthesis of tetra- and hexasaccharides (beta-D-glycero-D-manno-Hep p-(1-->4)-[alpha-l-Rha p-(1-->3)-beta-D-glycero-D-manno-Hep p-(1-->4)]n-alpha-L-Rha p-OMe (n = 1 and 2)) corresponding to multiple repeat units of the glycan from the surface-layer glycoprotein from Bacillus thermoaerophilus.
A fully stereocontrolled block synthesis of the title tetra- and hexasaccharides has been achieved taking advantage of the ability of the 4,6-O-benzylidene acetal to control the stereochemistry of the beta-D-glycero-D-mannoheptopyranoside unit and of a 2,3-O-diphenylmethylene acetal to install the alpha-L-rhamnopyranosidic linkages. Comparison of the spectral data for the hexasaccharide with that of the natural isolate confirms the structure of this very unusual and structurally challenging glycan.
Crich
David
D
Chemistry Department, Wayne State University, 5101 Cass Avenue, Detroit, Michigan 48202, USA. dcrich@chem.wayne.edu
Li
Ming
M
D001407:Bacillus / Q000737:chemistry*; D002236:Carbohydrate Conformation; D002240:Carbohydrate Sequence; D006023:Glycoproteins / Q000737:chemistry*; D008969:Molecular Sequence Data; D009844:Oligosaccharides / Q000138:chemical synthesis* / Q000737:chemistry; D011134:Polysaccharides / Q000737:chemistry*
D006023:Glycoproteins; D009844:Oligosaccharides; D011134:Polysaccharides