摘要:
A method of α-selective glycosylation comprising forming a cyclic protective group having a silyl acetal structure over hydroxyl groups at the 4- and 6-positions in a hexose or higher saccharide structure, which is a monosaccharide or the reducing end of an oligosaccharide (i.e., disaccharide or higher) or a sugar chain, and effecting a glycosylation reaction between this saccharide structure and an alcoholic hydroxyl or thiol group to thereby give glycosides of saccharide structure containing an α-glycoside at a high ratio. According to the above constitution, highly selective α-glycosylation in a saccharide structure can be carried out by an easy and convenient method.
摘要:
An α-selective glycosylation process of a glycosylation reaction between a sugar structure of hexose or an aldose having a chain with six or more carbon atoms in the molecule, which is a monosaccharide or a reducing end of an oligosaccharide with two or more monosaccharide residues connected by glycosidic or a sugar chain and alcoholic hydroxyl group or thiol group, to obtain a sugar structure glycoside containing α-glycoside at a high ratio, under the ring-shaped formation of a protective group in a silyl acetal structure over hydroxyl groups at positions 4 and 6 in the sugar structure. By the process, highly selective α-glycosylation of sugar structure can be progressed in a simple and efficient manner.
摘要:
Provided is a method for preparing 3-O-benzyl-1,2-O-isopropylidene-α-L-idofuranose, which comprises: (1) protecting hydroxyl of 3-O-benzyl-1,2-O-isopropylidene-α-D-glucofuranose (III) by benzoyl and methylsulfonyl to obtain 6-O-benzoyl-3-O-benzyl-1,2-O-isopropylidene-5-O-methylsulfonyl-α-D-glucofuranose (V); (2) subjecting compound (V) to a cyclization reaction under an alkaline condition to obtain 5,6-epoxy-3-O-benzyl-1,2-O-isopropylidene-α-L-idofuranose (VI); and (3) subjecting compound (VI) to a ring-opening reaction to obtain 3-O-benzyl-1,2-O-isopropylidene-α-L-idofuranose.
摘要:
Process for the preparation of a mercaptal of an oligosaccharide which process comprises the step of reacting the oligosaccharide with a thiol in the presence of an aqueous halocarboxylic or halosulphonic acid.
摘要:
Provided is a method for preparing 3-O-benzyl-1,2-O-isopropylidene-±-L-idofuranose, which comprises: (1) protecting hydroxyl of 3-O-benzyl-1,2-O-isopropylidene-±-D-glucofuranose (III) by benzoyl and methylsulfonyl to obtain 6-O-benzoyl-3-O-benzyl-1,2-O-isopropylidene-5-O-methylsulfonyl-±-D-glucofuranose (V); (2) subjecting compound (V) to a cyclization reaction under an alkaline condition to obtain 5,6-epoxy-3-O-benzyl-1,2-O-isopropylidene-±-L-idofuranose (VI); and (3) subjecting compound (VI) to a ring-opening reaction to obtain 3-O-benzyl-1,2-O-isopropylidene-±-L-idofuranose.