Synthesis of the complete series of mono acetates of N-acetyl-D-neuraminic acid

The short syntheses of each of the mono-acetates of N-acetyl-D-neuraminic acid are reported. These are important molecules for studying the mechanism and function of enzymes which utilise Neu5Ac as a substrate. However, until now these molecules were not available as pure compounds and instead had to be studied as mixtures. Neu4,5Ac(2) and Neu5,8Ac(2) were synthesised from a common precursor in 2 and 4 steps respectively, while Neu2,4Ac(2) and Neu5,7Ac(2) were synthesised in 3 and 4 steps respectively from another common precursor. Both precursors could be easily prepared in 3 steps from Neu5Ac itself. Importantly, no scrambling of the anomeric stereochemistry was detected throughout the course of these syntheses.