“…(E)-3-(6-Methoxy-4-oxo-4H-1-benzopyran-3-yl)acrylic acid ( 4c ). Yield = 81%; R f = 0.72 [ethyl acetate]; IR (neat) ν max : 3696, 3679, 3655, 3634, 3346, 3064, 2970, 2866, 2844, 2362, 2342, 2165, 2074, 2050, 1695, 1646, 1611, 1564, 1547, 1484, 1454, 1436, 1421, 1395, 1374, 1343, 1320, 1296, 1212, 1197, 1159, 1055, 1031, 1014, 941, 867, 830, 791, 726, 678 and 610 cm −1 ; UV/vis (MeOH) λ: 245 nm; 1 H NMR (400 MHz, DMSO): δ 12.37 (s, 1H, -COOH), 8.83 (s, 1H, H-2), 7.65 (d, J = 9.1 Hz, 1H, H-8), 7.47–7.40 (m, 3H, H-2′, H-7 and H-5), 7.10 (d, J = 15.9 Hz, 1H, H-1′), 3.86 (s, 3H, -OCH 3 ); 13 C NMR (101 MHz, DMSO): δ 174.96 (C-4 C=O), 167.81 (C-3′ C=O), 159.51 (C-2), 156.97 (C-6), 149.86 (C-8a), 136.02 (C-2′), 124.24 (C-4a), 123.53 (C-3), 121.11 (C-7), 120.14 (C-8), 117.31 (C-1′), 105.22 (C-5), 55.79 (OCH 3 ); HRMS (ESI-TOF) ( m / z ) C 13 H 10 O 5 calculated, 247.061, found 247.215 [M + H] + ; calculated, 269.043, found, 269.211 [M + Na] + ; and calculated, 285.017, found, 285.195 [M + K] + [ 48 ].…”