Reaction of Trimethylsilyl Enol Ethers with 2-Mercaptoethanol

Abstract

We wish to report that the acid catalyzed reaction of trimethylsilyl enol ethers with 2-mercaptoethanol gives hemithio ketals in moderate to good yield (eq 1).¹ The reaction is analogous to the recently reported reaction of trimethylsilyl enol ethers with diols.² The reaction is exothermic and rapid, requiring from 10 to 30 minutes for completion. A number of organic solvents were employed with essentially no change in t the results.³ The intermediate carbonium ion, I, is proposed to account for this reaction. The results of the reaction are shown in Table I.