Studies on the synthesis of two tetrasaccharides and the reactivity difference between them

Studies on the reactivity of two synthetic tetrasaccharides as glycosyl acceptors showed that condensation of the methyl α-glycoside with a disaccharide donor afforded a hexasaccharide, but condensation of the methyl β-glycoside with the disaccharide did not yield the corresponding hexasaccharide under the same conditions. A combination of theoretical results and 2D NMR indicated that the reactivity difference between the methyl α-glycoside and the methyl β-glycoside was determined mainly by steric effects.