Synthesis of a useful lauryl thioglycoside of sialic acid and its application

An efficient synthesis of a useful thioglycosyl donor 2 was accomplished directly from known peracetylated sialic acid methyl ester and 1-dodecanethiol (lauryl mercaptan) in the presence of BF3–OEt2. The reactivities of the lauryl glycosides for glycosidation by means of TMSOTf as a convenient promoter were investigated, and the lauryl thioglycoside showed satisfactory activities. Further transformation of the lauryl glycoside was also attempted to give a 5-azide analogue 14 of the sialic acid, which was also reacted with a secondary alcohol in the presence of TMSOTf to give known glycoside 15 in high yield.