1H NMR (400 MHz, CDCl3) δ 8.72 (s, 1H), 8.04 (s, 1H), 7.83 (d, J = 4.5 Hz, 1H), 7.48 (s, 1H), 7.37 (d, J = 4.7 Hz, 1H), 7.26 (s, 1H), 7.12 (s, 1H).13C{1H} NMR (101 MHz, CDCl3) δ 170.41, 156.78, 140.48, 137.82, 137.41, 136.69, 135.39, 132.33, 128.64, 127.85, 126.03, 125.24. HRMS (ESI) (M+H)+ Calcd. for C12H8NO2S2: 261.9992, Found: 261.9992.