Abstract: Disclosed is a method of preparation of 6-azido-2,4-diacetamido-2,4,6-trideoxy-D-mannose. This method includes the chemical reaction of compound of formula X: Wherein: R1 can be a C1 to C6 alkyl including methyl, ethyl, isopropyl; aryl including phenyl; each of these groups being substituted or not; and R2 can be a C1 to C6 alkyl including methyl, ethyl, isopropyl, tert-butyl, isobutyl; each of these groups being substituted or not; with a deprotecting reagent including a Lewis or Brönsted acid in a polar aprotic solvent, thereby obtaining a free C-1 OH group. The method can also start with the preparation from commercially available D-galactose pentaacetate, D-galactose tetraacetate or tetraacetyl D-galactosyl trichloroacetimidate. The step of deprotecting the anomeric position avoids the use of cerium and allows the easy purification of 6-azido-2,4-diacetamido-2,4,6-trideoxy-D-mannose.