Efficient dehydrative sialylation of C-4-aminated sialyl-hemiketal donors with Ph2SO/Tf2O.

An efficient approach to the dehydrative sialylation of various substrates with C-4-aminated sialyl-hemiketal donors by using the reagent combination of diphenyl sulfoxide and triflic anhydride is reported. By using a C-4-hindered non-nucleophilic amine auxiliary, excellent yields and high alpha-stereoselectivities were obtained for coupling with a wide range of primary and secondary acceptors.