Abstract Syntheses of N -acetyl- d -neuraminic acidderivatives 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