First example of the synthesis of bis(2-hydroxyethyl)dithioacetals from nitrobenzaldehydes and mercaptoethanol in the presence of methylchlorosilanes

Abstract

Aldehydes are known to readily convert into the corresponding 1,3-oxathiolanes and 1,3-oxathianes reacting with 1,2and 1,3-mercaptoalkanols in the presence of acid catalysts: scandium trifl ate [1], boron trifl uoride [2], p-toluenesulfonic acid [3], vanadium hydrogen sulfate [4], polyphosphoric acid on silica gel [5], etc. [6–8]. We formerly obtained open-chain dithioand diselenoacetals of thiophenecarbaldehydes with the use of trimethylchlorosilane [9–11]. In this study we discovered an uncommon formation of bis(2-hydroxyethyl)dithioacetals in the reaction of nitrobenzaldehydes with 2 equiv of 2-mercaptoethanol under the action of trimethylchlorosilane Me3SiCl. The process was carried out at room temperature by stirring the reagents in the 5–6-fold molar excess of Me3SiCl.