Glycosylation by sugar 1,2-O-(1-cyanobenzylidene) derivatives: influence of glycosyl-donor structure and promoter.
3,4,6-Tri-O-acetyl-1,2-O-(1-cyanobenzylidene)-alpha-D-galactopy ranoses with differently substituted aromatic nuclei have been synthesised and used as glycosyl donors in reactions with the acceptors methyl 2,3,4-tri-O-acetyl-6-O-trityl-beta-D-galactopyranoside (11) and methyl 2,4,6-tri-O-acetyl-3-O-trityl-beta-D-galactopyranoside (12). The glycosylation of 11 gave only beta products. The effeciency and stereoselectivity of the glycosylations of 12 depend on the nature of the substituent in the aromatic ring. The stereoselectivity for the formation of 1,2-trans-glycosidic bonds was the highest with the p-methoxy-benzylidene derivative with triphenylmethylium triflate as the promoter.
Kochetkov
N K
NK
N.D. Zelinsky Institute of Organic Chemistry, Russian Academy of Sciences, Moscow.
Betaneli
V I
VI
Kryazhevskikh
I A
IA
Ott AYa
D001597:Benzylidene Compounds; D002236:Carbohydrate Conformation; D002240:Carbohydrate Sequence; D002241:Carbohydrates; D004187:Disaccharides / Q000138:chemical synthesis* / Q000737:chemistry; D006031:Glycosylation; D007202:Indicators and Reagents; D009682:Magnetic Resonance Spectroscopy; D008969:Molecular Sequence Data; D009570:Nitriles; D009904:Optical Rotation
D001597:Benzylidene Compounds; D002241:Carbohydrates; D004187:Disaccharides; D007202:Indicators and Reagents; D009570:Nitriles