New rearrangement reactions of α-phenylsulphinylacrylate derivatives

Abstract

It is shown that α-phenylsuiphinylacrylate derivatives undergo three modes of rearrangement reactions induced selectively by the agent used. On treatment with an acidic reagent (hot dioxan–dilute sulphuric acid or acetic anhydride) a vinylogous-type Pummerer rearrangement takes place to produce the γ-hydroxylated or -acetoxylated phenylthio-derivatives, while under basic condition (pyridine–water or –acetic anhydride) a sequential prototropic shift and allylic sulphoxide-sulphenate rearrangement occurs regioselectively to give the sulphur-free γ-hydroxy or -acetoxy acrylates. When a highly nucleophilic agent (acetyl chloride, trifluoroacetic anhydride, or thionyl chloride) is used, the αβ-difunctionalised α-phenylthio-ester derivatives are formed through the third mode of rearrangement, an additive-type Pummerer reaction.