Highly r-Selective Synthesis of Sialyl Spirohydantoins by Regiospecific
Domino Condensation/OfN Acyl Migration/N-Sialylation
of Carbodiimides with Peracetylated Sialic Acid

Dengyou Zhang, Deju Ye, Enguang Feng, Jinfang Wang, Jianmei Shi, Hualiang Jiang, and Hong Liu

A novel and efficient process for the synthesis of R-sialyl spirohydantoin analogues via one-pot
sequential reaction involving various carbodiimides and peracetylated Neu5Ac is reported. BF3 3 Et2O
mediating intramolecular N-sialylation with excellent R-selectivity is first demonstrated.