Reaction of 2-(2,2,2-Trifluoroethylidene)-1,3-dithiane 1-Oxide with Ketones under Pummerer Conditions and Its Application to the Synthesis of 3-Trifluoromethyl-Substituted Five-Membered Heteroarenes
Easy as pie: With the aid of triflic anhydride, the title reaction resulted in nucleophilic attack of the carbonyl oxygen atom onto the activated cationic sulfur center and subsequent [3,3]‐sigmatropic rearrangement (see scheme). The products are precursors of the difficult‐to‐synthesize five‐membered 3‐trifluoromethyl heteroarene compounds.