“…1 H NMR [(CD3)2SO]: H 12.21 (br, 1H, NH), 7.58 (d, J 8.5 Hz, 1H, H-7), 7.54 (dd, J 8.6, 1.2 Hz, 1H, H-6), 7.41 (br s, 1H, H-4), 4.76 (t, J 5.4 Hz, 1H, CHO2), 4.37 (t, J 5.4 Hz, 2H, CH2N), 3.30 (s, 6H, 2 x CH3O). 13 A solution of 5 (0.306 g, 1 mmol) in a mixture of water (5 g) and conc. H2SO4 (45 g) was heated at 100 °C for 30 min and poured into ice-water.…”