N,N-Diacetylsialyl chloride--a novel readily accessible sialyl donor in reactions with neutral and charged nucleophiles in the absence of a promoter.

N,N-Diacetylneuraminic acid glycosyl chloride was prepared for the first time and made to react with various nucleophiles to give the corresponding alpha-glycosyl phosphate, beta-glycosyl dibenzyl phosphate, alpha-glycosyl azide, alpha-phenyl thioglycoside and alpha-glycosyl xanthate in 65-82% yields and high stereoselectivity while its reactions with simple alcohols were not stereoselective. The new sialyl donor made possible the first stereoselective synthesis of sialic acid glycosyl phosphate with alpha-configuration and highly efficient synthesis of beta-configured sialic acid glycosyl dibenzyl phosphate.