Abstract Ethyl methylsulfinylthioacetate undergoes Pummerer rearrangement with thionyl chloride, trifluoroacetic anhydride or with acetic anhydride-trifluoroacetic anhydride mixture, but not with acetic anhydride alone. These reactivities are compared to those for methyl methylsulfinylacetate and ω-methylsulfinylacetophenone and interpreted in terms of the difference in stability of the intermediate sulfinyl carbonium ions.
