Yoshiyasu Shitori

Synthesis of 9-O-acyl- and 4-O-acetyl-sialic acids☆

Various 9-O-acyl derivatives of N-acetyl- and N-glycoloyl-neuraminic acid, and O-(5-acetamido-3,5-dideoxy-D-glycero-alpha- and beta-D-galacto-2-nonulopyranosylonic acid)-(2----6)-O-beta-D-galactopyranosyl-(1----4)-D-glucopyranose were regioselectively synthesized by use of ortho esters. In addition, 5-acetamido-4-O-acetyl-D-glycero-D-galacto-2-nonulopyranosonic acid was prepared starting from the benzyl and methyl esters of N-acetylneuraminic acid.

Syntheses of 2-O-glycosyl derivatives of N-acetyl-d-neuraminic acid

Abstract Syntheses of N -acetyl- d -neuraminic acid derivatives are reported. Methyl 4,7,8,9-tetra- O -acetyl- N -acetyl-2-chloro-2-deoxy-β- d -neuraminate ( 3 ) was prepared directly from methyl N -acetyl-β- d -neuraminate ( 2 ) in good yield. Koenigs-Knorr reaction of 3 with an excess of methanol gave the methyl α-glycoside of methyl N -acetyl- d -neuraminate ( 4 ). 2,3- O -Isopropylidene- d -ribono-1,4-lactone, 2,3- O -isopropylideneuridine, and 5-fluoro-2,3- O -isopropylideneuridine reacted with 3 to give anomeric mixtures of methyl N -acteyl- d -neuraminate derivatives. The stereochemistry of these compounds was confirmed from n.m.r. and c.d. spectra, and measurements of the rate of hydrolysis of the glycosidic bond.