ChemInform Abstract: Highly Efficient α‐C‐Sialylation Promoted by (p‐Tol)2SO/Tf2O with N‐Acetyl‐5‐N,4‐O‐oxazolidione Protected Thiosialoside as Donor.

Abstract

Based on a preactivation protocol with (p-Tol)2SO/Tf2O, a practical, straightforward, and high-yielding synthesis of α-sialyl C-glycosides was accomplished by coupling N-acetyl-5-N,4-O-oxazolidione protected thiosialoside with various trimethylsilyl enol ethers and allyltrimethylsilanes. High yields and excellent α-selectivities were obtained for the strong π-nucleophiles with large nucleophilicity values (N = 4.4–9.0), irrespective of whether silyl enol ethers, silyl ketene acetals or allyltrimethylsilanes were used for the electrophilic C-sialylation.