Reaction Steps
Synthetic details: To a solution of phenyl trifluoromethyl sulfoxide (5) (485 mg, 2.5 mmol) in dry 1,3-difluorobenzene (7.4 mL, 75 mmol) was added (CF3SO2)2O (2.10 mL, 12.5 mmol) at 0° C. The reaction mixture was stirred for 2 h at 0° C., and then at rt for another 20 h. The solvent was evaporated under reduced pressure and the residue was purified by column chromatography on silica gel using CH3CN—CH2Cl2 (1:4) as eluent. The product was obtained as a white crystal (770 mg, 70%), m. p. 78-9° C. (recrystallized from ethyl acetate/hexanes). IR (nujol): 3099 (s), 1600 (s), 1479 (s), 1450 (s), 1200 (s) (cm−1); 1H NMR (CDCl3): 8.26 (d, J2′3′=8.1 Hz, J4′3′=8.1 Hz, 3H), 7.90 (bd, J657.5 Hz, 1H), 7.75 (dd, J3′2′=7.8 Hz, J3′4′=7.8 Hz, 2H), 7.45 (dd, J56=8.1 Hz, J54F=7.8 Hz, 1H), 7.25 (dd, J32F=9.0 Hz, J34F=9.0 Hz, 1H); 19F NMR (CDCl3): −47.6 (s, 3F), −78.3 (s, 3F), −91.7 (s, 1F), −98.2 (s, 1F); 13C NMR (CDCl3): 168 (d, J=261 Hz), 163 (d, J=262), 138, 137, 133, 132, 126 (q, J=262), 123 (q, J=262 Hz), 120, 117, 115, 108 ppm; FAB+-MS [m/e (species, intensity)]: 291 ((C13H8F5S)+, 100), 222 ((C13H8F5S)+-CF3, 80.6), 145 ((C13H8F5S)+-C6H5-CF3, 15.0) ); Chemical analysis: Calculated for C14H8F8O3S2: C, 38.18; H, 1.83; F, 34.52. Found: C, 37.97; H, 1.88; F, 34.90.
