1H NMR (400 MHz, DMSO-D6) δ 12.14 (s, 1H, COOH), 9.56 (s, 1H, H-11), 7.49 (d, J = 15.9 Hz, 1H, H-7), 7.28 (d, J = 2.0 Hz, 1H, H-2), 7.08 (dd, J = 8.3, 2.0 Hz, 1H, H-5), 6.79 (d, J = 8.1 Hz, 1H, H-6), 6.37 (d, J = 15.9 Hz, 1H, H-8), 3.81 (s, 3H, OCH3-12). 13C NMR (100 MHz, DMSO-D6) δ 168.08 (C-9), 149.13 (C-3), 147.96 (C-4), 144.59 (C-7), 125.82 (C-1), 122.91 (C-6), 115.67 (C-5), 115.55 (C-8), 111.14 (C-2), 55.71 (C-12).
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