Systematic VCD studies of N-acetylneuraminic acid (Neu5Ac), a recognition-related unique carbohydrate, were performed for the first time. Two pairs of anomeric isomers regarding a quaternary C2 asymmetric carbon of Neu5Ac derivatives were synthesized. VCD spectral patterns around the ester carbonyl region, as well as other Mid-IR regions, would be practical markers to distinguish the C2 stereochemistry.