Patent ID: 8653255

Claim:
A process for producing an aldehyde derivative of a reducing terminal sialic acid of a starting material having a sialic acid at a non-reducing terminal, which process comprises: a) a selective oxidation step to oxidise the non-reducing terminal sialic acid unit at the 7,8 vicinal diol group to form a 7-aldehyde; b) a reduction step to reduce the 7-aldehyde group of the non-reducing terminal sialic acid to a corresponding alcohol, wherein the reduction step additionally reduces the reducing terminal sialic acid to effect ring opening of the reducing terminal sialic acid whereby a vicinal diol group is formed; c) an oxidation step which oxidises the reducing terminal unit but does not oxidise the moiety produced in the oxidation and reduction reactions of the non-reducing terminal unit; and d) a conjugation step to conjugate the reducing terminal sialic acid to a substrate.