1H NMR (400 MHz, CDCl3) δ 7.84 (d, J = 8.4 Hz, 2H), 7.29 (d, J = 8.3 Hz, 2H), 5.93 (s, 1H), 5.66 (s, 1H), 3.53 (s, 2H), 2.13 (s, 3H); 13C NMR (100 MHz, CDCl3) δ 195.4, 152.2, 143.7, 135.7, 131.4, 125.9, 120.2, 35.3, 30.6 (d, J = 180.8 Hz), 15.5. HRMS (EI): calcd for C12H11F3O2S: 276.0432; found: 276.0431.