Use of Phenyl 2-α-Selenoglycosides of N-Acetylneuraminic Acid as a Glycosyl Donor for the Glycosylation Reactions

Phenyl 2-α-selenoglycosides of Neu5Ac 2 were successfully prepared from the corresponding peracetylated chloro derivative of Neu5Ac 1 and phenylselenol in the presence of N,N-di-isopropylethylamine in excellent yields. The reaction of 2 with various alcohols was effectively catalyzed by NIS/TfOH or DMTST to produce a variety of glycosides in moderate yields. Selective activation of 2 over phenyl 2-α-thioglycoside of Neu5Ac 6 with AgOTf/K2CO3 was also achieved.