¹H NMR (400 MHz, CDCl₃): δ 8.19 (d, J = 3.0 Hz, 1H), 7.75 (d, J = 4.5 Hz, 2H), 7.46 (d, J = 5.9 Hz, 1H), 7.38 (d, J = 3.1 Hz, 1H), 7.31-7.27 (m, 1H), 7.24 (t, J = 3.9 Hz, 1H), 2.48 (s, 4H). ¹³C NMR (100 MHz, CDCl₃): δ 172.2, 150.3, 149.6, 141.6, 137.6, 137.0, 134.3, 134.2, 133.9, 128.3, 127.8, 122.7, 117.6, 18.2. HRMS (EI): calcd for C₁₄H₁₀O₂S₃: 305.9843; found, 305.9839.