[摘要]:An efficient synthesis of a(2,9) trisialic acid has been achieved via one-pot glycosylation and polymer-assisted deprotection. The synthesis involves chemo- and regioselective a-sialylation of ethylthiosialoside with the S-benzoxazolyl (S-Box) sialyl donor. Use of a pre-linker to link an activated ester and a vinyl ether via a carbon chain enables polymer-assisted deprotection of the protected trisialic acids.