Sialic acid derivatization procedures

Azido-NeuAc (3) was synthesized from commercial NeuAc in an efficient two-step procedure in 65% overall yield. 9-Azido-NeuAc (3) was easily derivatized to afford 9-substituted sialic acid analogs that are of great... 

Terminal sialic acids are released in a good yield under mild acidic conditions like formic acid, pH 2 (1 h, 70 X), 0.1 N H2SO4 or 0.1 N HCl (1 h, 80 "C) (Schauer 1978). These conditions do not lead to N-deacylation however, 0-deacylation occurs to an extent of about 50%. Mild acid hydrolysis has frequently been chosen to release N,0-acylneuraminic acids from biological materials for identification by g.l.c./m.s. Derivatization procedures are presented in sections II. 3 and II.4. For g.l.c./m.s., see section III.2. Quantitative g.l.c. procedures after pertrimethyl-silylation (section II.4) have been worked out by Casals-Stenzel et al (1975). Because of partial 0-deacylation during hydrolysis and subsequent isolation, quantitative analysis of the various N,0-acylneuraminic acids present in native biological material is still a serious problem. The nonavailability of pure N,0-acylneuraminic acids as standard compounds makes it also difficult to determine reliable molar adjustment factors for g.l.c. analysis. 

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