2-Position-Selective Trifluoromethylthiolation of Six-Membered Heteroaromatic Compounds

The regioselective C-H trifluoromethylthiolation of six-membered heteroaromatic compounds via nucleophilic attack of a CF₃S source on the electrophilically activated six-membered heteroaromatic ring was developed. The reaction proceeds in good yield with good functional group tolerance, even on a gram-scale. The key to the successful regioselective transformation is the presence of an additive (2,4-dinitrobenzenesulfonyl chloride). The regioselective trifluoromethylthiolation of quinidine derivative is also demonstrated. Trifluoromethylthiolation, followed by S-oxidation, affords the corresponding sulfones.