A regio- and stereo-selective introduction of azide at C-4 of 2,3-unsaturated N-acetylneuraminic acids

The regio- and stereo-selective azidation of the peracetate methyl esters of 4-epi-Neu5Ac2en and 6-thio-4-epi-Neu5Ac2en has been achieved using Pd(0) chemistry in good yield (> 80%). These 4-epi-azido-4-deoxy-Neu5Ac2en derivatives provide interesting biological probes.