A new method of oligosaccharide synthesis: rhamnobioses

Article abstract of DOI:10.1016/0008-6215(84)85377-X

A semi-synthetic approach to (1->2)-α- and (1->3)-α-linked rhamnobioses is presented.The method involves condensation of benzyl 2-O- or 3-O-benzoyl-4-O-benzyl-α-L-rhamnopyranoside (5) with 1-O-acetyl-2,3,6-trideoxy-α,β-DL-glycero-hex-2-enopyranos-4-ulose(6), isolation of the L-L and D-L forms of the resulting disaccharide derivatives, reduction of the carbonyl groups to give α-erythro unsaturated products, and cis-hydroxylation to form the rhamnobiose derivatives.Removal of the protecting groups then gave α-L-Rhap-(1->2)-L-Rhap, α-L-Rhap-(1->3)-L-Rhap, and the corresponding D-L stereoisomers.The (1)H- and (13)C-n.m.r. data are of diagnostic value in differentiating the stereoisomers. 1-(2-Furyl)ethanol was resolved into its enantiomers, and the (+)-form was converted into (+)-6 which in turn was condensed with 5.The structure of the products indicated that (+)-1-(2-furyl)ethanol has the R configuration.