Synthesis and crystal structure of methyl [formula omitted], the methyl α-glycoside of the terminal unit, and presumed antigenic determinant, of the O-specific polysaccharide of Vibrio cholerae O:1, serotype Ogawa

Abstract

Methyl 4- azido-4,6-dideoxy-3-O- benzyl-α- d- mannopyranoside and its analogous 3- O-(4-methoxybenzyl) derivative were methylated and the 2- O-methyl derivatives formed were converted into methyl 4- amino-4,6-dideoxy-2-O- methyl-α- d-mannopyranoside . Reaction of the latter with 3- deoxy- l -glycero- tetronolactone gave the methyl glycoside of 4,6- dideoxy-4-(3- deoxy- l -glycero- tetronamido)-2-O- methyl-α- d-mannopyranose , the monosaccharide that is reported to be the terminal moiety of the O-specific polysaccharide of Vibrio cholerae O:1, serotype Ogawa. The unit cell packing of the compound, which crystallized as a monohydrate, differs from that of the previously described crystalline compound lacking the 2- O-methyl group. The unmethylated sugar is the terminal moiety of the O-specific polysaccharide of Vibrio cholerae O:1, serotype Inaba. The crystal structure of methyl 4,6- dideoxy-2-O- methyl-4-trifluoroacetamido-α- d-mannopyranoside is also described.