A facile synthesis of Neu5Ac2en derivatives from the glycosides of N-acetylneuraminic acid

In a one-pot reaction, acetolysis of some functionalised methyl glycosides of N-acetylneuraminic acid (Neu5Ac) methyl ester provides a direct and effi cient entry into the corresponding 2,3-unsaturated (Neu5Ac2en) derivatives. Other glycosides of Neu5Ac, such as benzyl and 2-(trimethylsilyl)ethyl gly cosides, like their methyl counterpart, are also transformed into the 2,3-u nsaturated analogues. This reaction has also been applied to the synthesis of some novel 4-bis-substituted-Neu5Ac2en derivatives, which in turn has le d to the synthesis of the C-4 homologue of the per-acetylated methyl ester of Neu5Ac2en, compound 10.