Simultaneous 2-O-deacetylation and 4-amination of peracetylated Neu5Ac: application to the synthesis of (4→4)-piperazine derivatives linked sialic acid dimers
A simultaneous stereoselective 2-O-deacetylation and 4-amination reaction of peracetylated Neu5Ac 1 has been established with cyclic secondary amines, such as 1-N-Boc-piperazine. Four C2-symmetric and two asymmetric sialic acid dimers with (4→4)-piperazine derivatives linked were synthesized. They may serve as precursors of unnatural polysialic acids.