A Remarkable Influence of a Trifluoromethyl Group on the Reactions of β‐Mercaptoalcohols with Fluorinated α‐Bromoenones

Abstract

Isomeric fluorinated α‐bromoenones react with dinucleophilic β‐mercaptoalcohols in CH2Cl2 at room temperature in the presence of Et3N in a multistep process. Depending on the position of the CF3 group, different O,S‐heterocycles or non‐cyclic products were obtained. With 3‐bromo‐1,1,1‐trifluorobut‐3‐en‐2‐ones derivatives of 1,4‐oxathianes were formed, but isomeric 2‐bromo‐4,4,4‐trifluorobut‐2‐en‐1‐ones yielded 1,3‐oxathiolanes or non‐cyclic sulfides. The thia‐Michael addition is proposed as the initial step of the reaction, and the final heterocyclization is governed by the location of the CF3 group.