1H NMR (400 MHz, CDCl3) 1H NMR (400 MHz, CDCl3) δ 8.07 (d, J = 8.0 Hz, 2H), 8.03 (d, J = 8.1 Hz, 2H), 7.95 (d, J= 8.0 Hz, 2H), 7.33 (s, 1H), 7.04-6.97 (m, 4H), 3.91 (s, 3H), 3.88 (s, 3H), 2.45(s, 3H). 13C NMR (100 MHz, CDCl3) δ 180.3, 163.3, 160.2, 154.0, 150.2, 132.4, 131.7, 129.9, 128.1, 124.1, 114.3, 114.1, 113.8, 55.6, 55.4, 18.3. HRMS (EI): calcd for C20H18O4S: 354.0926; found, 354.0928