Synthesis, NMR and conformational studies of branched oligosaccharides. 3. Synthesis of 2,3-di-O-glycosylated methyl α-L-rhamnopyranoside derivatives

N. E. Nifant'ev, G. M. Lipkind, A. S. Shashkov, N. K. Kochetkov

N. D. Zelinsky Institute of Organic Chemistry, Academy of Sciences of the USSR, Moscow

Abstract: Within a programme of spectral (NMR) and conformational studies of 2,3-di-O-glyco-sylated derivatives of α-L-rhamnopyranose, a series of branched oligosaccharides (I)(XII) was synthesized.

X-(1-2)
       \
       α-L-Rhap-OMe  (I) - (XII)
      /
Y-(1-3)

          X          Y
       --------------------
(I)    α-D-Manp   α-L-Rhap
(II)   α-D-Manp   β-D-Glcp
(III)  α-D-Manp   β-L-Fucp
(IV)   β-D-Glcp   α-D-Manp
(V)    β-D-Glcp   α-D-Manp
(VI)   β-D-Glcp   β-L-Fucp
(VII)  α-L-Fucp   β-L-Fucp
(VIII) α-L-Fucp   α-D-Manp
(IX)   α-L-Fucp   β-D-Glcp
(X)    β-L-Fucp   α-L-Rhap
(XI)   β-L-Fucp   α-D-Manp
(XII)  β-L-Fucp   β-D-Glcp

The preparation was carried out using stereoselective glycosylation of (13)-linked disaccharidic glycosyl-acceptors and appropriately substituted methyl 2-O-(β-L-fu-copyranosyl)-α-L-rhamnopyranoside. In the synthesis of compounds (VII)(IX) the α-L-fucopyranosyl residue was stereoselectively introduced using benzobromofucose and per-O-acetylated 1-thiofucoside.

Russian Journal of Bioorganic Chemistry 1991, 17 (9):1229-1250

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