Synthesis of a sialic acid dimer derivative, 2'alpha-O-benzyl Neu5Ac-alph-(2-->5)Neu5Gc.

The preparation of a disaccharide 2, Neu5Ac-alpha-(2-->5)Neu5Gc having a alpha-benzyl protecting group at the reducing end, by the coupling of the easily accessible building units 4 and 5 is described. Subsequent deprotection of the coupling adduct led to the isolation of the target compound 2 in high yield.