S-(Trifluoromethyl)benzothioate (TFBT) has been developed as an inexpensive, bench-stable, and user-friendly trifluoromethylthiolation reagent, which can be easily synthesized by using KF as the only fluorine source.
Under the protection of nitrogen, potassium
fluoride (23.2 g, 400 mmol, 4.0 equiv), 18-c-6 (31.8 g, 120 mmol,
1.2 equiv) and acetonitrile (200 mL) were added to a dry Schlenk
tube. After cooling to 15°C, thiophosgene (9.2 mL, 120 mmol,
1.2 equiv) was added, and the mixture was vigorously stirred for
4 h. Then, the temperature was cooled to 30°C and benzoyl
chloride (11.6 mL, 100 mmol, 1.0 equiv) added. After stirring for
another 2 h, the reaction was quenched by water, raised to room
temperature, and extracted with ether (3×100 mL). The organic
phases were combined, washed with water and saturated brine,
and dried with anhydrous Na2SO4. After filtration, the solution was
concentrated by evaporation and the residue was distilled under
reduced pressure (8 Torr, 70–80°C) to provide Benzenecarbothioic acid, S-(trifluoromethyl) ester as a yellow liquid
(12.6 g, 61%).
