1H NMR (400 MHz, CDCl3) δ 7.48-7.43 (m, 2H), 6.89 (d, J = 8.2 Hz, 1H), 5.82 (s, 1H), 5.61 (s, 1H), 3.95 (s, 3H), 3.94 (s, 3H), 3.54 (s, 2H), 2.12 (s, 3H); 13C NMR (100 MHz, CDCl3) δ 195.7, 153.2, 149.0, 143.8, 130.0, 124.7, 123.6, 111.6, 109.7, 56.0, 55.9, 35.9, 15.5. HRMS (EI): calcd for C13H16O3S: 252.0820; found: 252.0817.