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 alpha-glycoside with a disaccharide donor afforded a hexasaccharide, but condensation of the methyl beta-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 alpha-glycoside and the methyl beta-glycoside was determined mainly by steric effects.