Synthesis of partially O-acetylated N-acetylneuraminic acid using regioselective silyl exchange technology

Abstract

Postglycosylation acetylation of sialic acid imparts unique roles to sialoglycoconjugates in mammalian immune response making structural and functional understanding of these analogues important. Five partially O-acetylated Neu5Ac analogues have been synthesized. Reaction of per-O-silylated Neu5Ac ester with AcOH and Ac2O in pyridine promotes regioselective silyl ether/acetate exchange in the following order: C4 (2°) > C9 (1°) > C8 (2°) > C2 (anomeric). Subsequent hydrogenolysis affords the corresponding sialic acid analogues as useful chemical biology tools.