New Synthetic Route for the Preparation of 4-Phenylthio-4-butanolide Derivatives by the Use of the Pummerer Rearrangement

The Pummerer rearrangement reaction of 2- or 3-substituted 4-(phenylsulfinyl) butyric acids in the presence of an excess amount of acetic anhydride and a catalytic amount of p-toluenesulfonic acid in refluxing toluene for 1 h afforded 2- or 3-substituted 4-phenylthio-4-butanolide (17a–f). Thermolysis in pyridine of 4-phenylsulfinyl 4-butanolides, which were prepared by oxidation of 17a–f, afforded 2- or 3-substituted 2- or 3-buten-4-olides.