1H NMR (400 MHz, CDCl3): δ 7.98 (d, J = 8.2 Hz, 4H), 7.33 (t, J = 6.4 Hz, 4H), 7.31 (s, 1H), 2.56 (s, 3H), 2.53 (s, 3H), 2.47 (s, 3H). 13C NMR (100 MHz, CDCl3): δ 180.5, 153.4, 150.2, 145.5, 140.3, 133.3, 129.8, 126.7, 126.0, 125.9, 125.0, 123.9, 117.6, 18.1, 15.2, 14.8. HRMS (EI): calcd for C20H18O2S3: 386.0469; found, 386.0473.