The 6-O-trityl derivative of 2,3:5,6:3',4'-O-isopropylidenelactose dimethyl acetal (1) was converted through an oxidation/oximation/reduction sequence involving the free 2-OH group of the D-galactose moiety into the protected disaccharide 5 in up to 75% yield. The complete deprotection of 5 produced the disaccharide 4-O-(2-acetamido-2-deoxy-beta-D-talopyranosy)-D-glucose glucose (7a). The oxime LiAlH4 reduction step produced some unexpected side-products, the most abundant of which, the dimethyl acetal 9, deriving from cleavage of the D-glucose moiety, was formed only when the reaction was conducted in refluxing THF, but not when Et2O was used as the solvent.
Stereoselective synthesis of 4-O-(2-acetamido-2-deoxy-beta-D-talopyranosyl)-D-glucose derivatives from lactose
CATELANI, GIORGIO;D'ANDREA, FELICIA;
2000-01-01
Abstract
The 6-O-trityl derivative of 2,3:5,6:3',4'-O-isopropylidenelactose dimethyl acetal (1) was converted through an oxidation/oximation/reduction sequence involving the free 2-OH group of the D-galactose moiety into the protected disaccharide 5 in up to 75% yield. The complete deprotection of 5 produced the disaccharide 4-O-(2-acetamido-2-deoxy-beta-D-talopyranosy)-D-glucose glucose (7a). The oxime LiAlH4 reduction step produced some unexpected side-products, the most abundant of which, the dimethyl acetal 9, deriving from cleavage of the D-glucose moiety, was formed only when the reaction was conducted in refluxing THF, but not when Et2O was used as the solvent.I documenti in IRIS sono protetti da copyright e tutti i diritti sono riservati, salvo diversa indicazione.