N-Acetyl-5-N,4-O-oxazolidinone-Protected Sialyl Sulfoxide: An α-Selective Sialyl Donor with Tf2O/(Tol)2SO in Dichloromethane


  • Tf=CF3SO2, Tol=p-CH3C6H4.


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Sweet as sugar: Sialyl sulfoxide protected by N-acetyl-5-N,4-O-oxazolidinone was readily prepared, and its coupling to various sugar acceptors was investigated. When the reaction was promoted by Tf2O/(Tol)2SO, efficient and highly α-selective sialylation yielded α(2,6), α(2,3), and α(2,4) glycosidic linkages between sialic acid and glucose/glacotose.