α,α-二羰(酯)基烯酮二硫代缩醛化合物的碱性分解反应

Studies on the Basic Assisted Decomposition ofα,α-Dioxo(Ester)Ketene Dithioacetals

在乙硫醇钾或醇钠（钾）作用下，α，α－二羰（酯）基烯酮二硫代缩醛（１）可能经由逆Ｃｌａｉｓｅｎ缩合历程生成相应的β，β－双烷硫基丙烯酸酯或α－羰基烯酮二硫代缩醛类化合物（２）。以醇钠（钾）为碱时，２的产率较低．用乙硫醇钾为碱时，２的产率可达６６％以上；本实验为化合物２的合成提供了一条简单、有效的途径．

A facile method for the synthesis of β,β-dialkylthioacrylate is described in this paper. The title compounds 1 prepared easily in nearly quantitive yields from corresponding β-dicarbonyl substrates were decomposed to give compounds 2,assisted by either potassium ethylthioate or sodium(potassium)alkoxide.As shown by the experiments,the former base is very effective, the yields of 2 reach to the range of 66%─98%.The decomposition was proposed to proceed via the Contra-Claisen condensation process in mechanism. This route is common, convenient and is the first example for the synthesis of the compounds 2 with different thioacetal groups in high yields.