(
ꢆ
)-7,8-Dihydroxy-4-(3,4,5-trimethoxyphenyl)-3,4-dihydrocoumarin (14). White solid, mp 221–223ꢀC, yield 52.6%.
IR (KBr, ꢇ, cm–1): 3471 (OH), 1751 (CO), 1597, 1512, 1466, 1311, 1246, 1122, and 1007. H NMR (400 MHz, CDCl3, ꢁ,
ppm, J/Hz): 3.03 (2H, m, H-3), 3.78 (6H, s, 2 ꢅ OCH3), 3.82 (3H, s, OCH3), 4.22 (2H, dd, J = 6 and 7.6), 6.33 (2H, s, H-2ꢄ and
H-6ꢄ), 6.45 and 6.67 (each H, d, J = 8.8, H-5 and H-6). 13C NMR (100 MHz, CD3COCD3, ꢁ): 37.3, 40.7, 56.2, 60.9, 104.5,
111.3, 117.6, 119.0, 131.1, 136.0, 139.3, 144.3, 153.6, 166.7. MS m/z (%): 346 [M]+, 328 [M – H2O]+, 313 [M – CH3 – H2O]+,
273, 257, 243, 229, 181, 115.
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(ꢆ)-7,8-Dihydroxy-4-(4-methoxyphenyl)-3,4-dihydrocoumarin (15). White solid, mp 166–168ꢀC, yield 62.2%.
IR (KBr, ꢇ, cm–1): 3413 (OH), 1751 (CO), 1612, 1514, 1311, 1284, 1247, 1180, 1144, and 1007. 1H NMR (400 MHz, CDCl3, ꢁ):
3.01 (2H, m, H-3), 3.78 (3H, s, OCH3), 4.24 (1H, t, J = 6.8, H-4), 6.39 (2H, 2 ꢅ d, J = 8.4, H-5 and H-6), 6.85 and 7.04 (4H,
2 ꢅ d, J = 8.8, H-2ꢄ, H-6ꢄ, H-3ꢄ, and H-5ꢄ). 13C NMR (100 MHz, CD3COCD3, ꢁ): 37.9, 40.2, 55.4, 111.7, 114.9, 114.9, 118.5,
119.1, 129.3, 133.8, 134.5, 141.2, 146.3, 159.6, 167.9. MS m/z (%): 286 [M]+, 268 [M – H2O]+, 243, 229, 200, 115.
(ꢆ)-6-Hydroxy-4-(3,4-dimethoxyphenyl)-3,4-dihydrocoumarin (16). White solid, mp 168–170ꢀC, yield 62.3%.
IR (KBr, ꢇ, cm–1): 3273 (OH), 1714 (CO), 1521, 1487, 1247, 1244, and 1186. 1H NMR (400 MHz, CDCl3, ꢁ, ppm, J/Hz):
3.0 (2H, m, H-3), 3.79 and 3.82 (each 3H, s, OCH3), 4.17 (1H, dd, J = 6 and 8.4, H-4), 6.41 (1H, d, J = 2.8, H-2ꢄ), 6.63 (1H, d,
J = 2.4, H-5), 6.68 (1H, dd, J = 2 and 8, H-7), 6.72 (1H, dd, J = 2.8 and 8.8, H-6ꢄ), 6.79 (1H, d, J = 8, H-8), 6.96 (1H, d, J = 8.8,
H-5ꢄ). 13C NMR (100 MHz, CDCl3, ꢁ): 36.9, 40.4, 55.9, 110.6, 111.6, 114.5, 115.3, 118.0, 119.9, 127.4, 132.3, 145.4, 148.5,
149.4, 152.5, 168.2. MS m/z (%): 300 [M]+, 282 [M – H2O]+, 267 [M – CH3 – H2O]+, 257, 243, 227, 151, 115.
(ꢆ)-6-Hydroxy-4-(3,4,5-trimethoxyphenyl)-3,4-dihydrocoumarin (17). White solid, mp 174–176ꢀC, yield 71.4%.
IR (KBr, ꢇ, cm–1): 3421 (OH), 1757 (CO), 1504, 1454, 1232, 1195, and 1122. 1H NMR (400 MHz, CDCl3, ꢁ, ppm, J/Hz): 2.98
(2H, m, H-3), 3.77 and 3.80 (9H, 2s, 6H and 3H each, 3 ꢅ OCH3), 4.17 (1H, t, J = 6.4, H-4), 6.33 (2H, s, H-2ꢄ and H-6ꢄ), 6.55
(1H, dd, J = 2.4 and 8.6, H-6), 6.64 (1H, d, J = 2.4, H-8), 6.85 (1H, d, J = 8.6, H-5). 13C NMR (100 MHz, CDCl3, ꢁ): 36.8, 41.0,
56.1, 60.8, 104.6, 114.5, 115.5, 118.0, 126.9, 135.7, 137.2, 145.3, 152.6, 153.6, 168.1. MS m/z (%): 330 [M]+, 312 [M – H2O]+,
297 [M – H2O – CH3]+, 257, 213, 181, 128.
(ꢆ)-6-Hydroxy-4-(4-methoxyphenyl)-3,4-dihydrocoumarin (18). White solid, mp 170–172ꢀC, yield 52.2%.
IR (KBr, ꢇ, cm–1): 3320 (OH), 1732 (CO), 1510, 1456, 1309, 1252, 1194, 1155, and 831. 1H NMR (400 MHz, CDCl3, ꢁ, ppm,
J/Hz): 2.96 (2H, m, H-3), 3.75 (3H, s, OCH3), 4.19 (1H, dd, J = 6.0 and 8.4, H-4), 6.38 (1H, d, J = 2.4, H-5), 6.71 (1H, dd,
J = 3.2 and 8.8, H-7), 6.85 (2H, dd, J = 2 and 6.0, H-2ꢄ and H-6ꢄ), 6.96 (1H, dd, J = 8.8, H-5), 7.05 (2H, dd, J = 2 and 6.0, H-3ꢄ and
H-5ꢄ). 13C NMR (100 MHz, CDCl3, ꢁ): 37.0, 39.9, 55.3, 76.7, 77.0, 77.2, 77.3, 114.5, 114.6, 114.7, 115.3, 118.0, 127.5, 128.7,
131.9, 145.5, 152.3, 159.0, 168.2. MS m/z (%): 270 [M]+, 252 [M – H2O]+, 227 [M – H2O – CH3]+, 213, 197, 128.
(ꢆ)-7-Methoxy-4-(4-methoxyphenyl)-3,4-dihydrocoumarin (19). White solid, mp 136–137ꢀC, yield 52.1%.
IR (KBr, ꢇ, cm–1): 2937, 1761 (CO), 1510, 1252, 1124, 1030, and 831. 1H NMR (400 MHz, CD3COCD3, ꢁ, ppm, J/Hz): 3.03
(2H, m, H-3), 3.76 and 3.81 (6H, 2s, 3H and 3H each, 2 ꢅ OCH3), 4.37 (1H, t, J = 6.4, H-4), 6.66 (1H, d, J = 2.4, H-8), 6.69
(1H, dd, J = 2.4 and 8.4, H-6), 6.89 and 7.11 (each 2H, d, H-2ꢄ, H-3ꢄ, H-5ꢄ, H-6ꢄ), 6.95 (1H, d, J = 8.4, H-5). 13C NMR
(100 MHz, CDCl3, ꢁ): 37.4, 39.2, 55.2, 55.4, 102.4, 110.6, 114.3, 117.9, 128.4, 128.7, 132.6, 152.3, 158.8, 159.8, 167.7.
MS m/z (%): 284 [M]+, 256 [M – CO]+, 241 [M – CO – CH3]+, 227, 211, 128. The physical/spectral data of the compound
matched well with those reported earlier [5, 14].
(ꢆ)-7-Methoxy-4-(3,4,5-trimethoxyphenyl)-3,4-dihydrocoumarin (20). White solid, mp 131–133ꢀC, yield 57.2%.
IR (KBr, ꢇ, cm–1): 3456, 1761 (CO), 1593, 1506, 1460, 1130. 1H NMR (400 MHz, CDCl3, ꢁ, ppm, J/Hz): 3.00 (2H, m, H-3),
3.78, 3.79, and 3.81 (12H, 3s, 6H, 3H, and 3H each, 4 ꢅ OCH3), 4.19 (1H, t, J = 7.6, H-4), 6.33 (1H, s, H-2ꢄ and H-6ꢄ), 6.64
(1H, dd, J = 2.4 and 8.4, H-6), 6.66 (1H, d, H-8), 6.89 (1H, d, J = 8.4, H-5). 13C NMR (100 MHz, CDCl3, ꢁ): 37.4, 40.5, 55.5,
56.1, 60.8, 102.5, 104.4, 110.8, 117.4, 128.9, 136.4, 137.3, 152.4, 153.6, 160.0, 167.6. MS m/z (%): 344 [M]+, 329 [M –
CH3]+, 311 [M – CO – CH3] +, 271, 220, 177, 121, 77. The physical/spectral data of the compound matched well with those
reported earlier [5, 14].
Synthesis of 4-Arylcoumarins 23, 24, 25, 26. A solution of the appropriate phenol (11 mmol) and the appropriate
arylpropargyl acid (10 mmol) in 10 mLCF3COOH was stirred at room temperature for 4–8 h. The reaction mixture was poured
onto ice water, extracted with ethyl acetate (2 ꢅ 150 mL), washed with water (150 mL), and dried. The solvent was removed
under reduced pressure to obtain the crude product, which was then purified by chromatography on silica gel.
7-Hydroxy-4-(3,4-dimethoxyphenyl)coumarin (23). White solid, mp 233–234ꢀC, yield 56.4%. IR (KBr, ꢇ, cm–1):
3194 (OH), 1695 (CO), 1624, 1599, 1518, 1263, and 1140. 1H NMR (400 MHz, CD3COCD3, ꢁ, ppm, J/Hz): 3.90 and 3.94
(6H, s, 3H and 3H, 2 ꢅ OCH3), 6.20 (1H, s, H-3), 6.74 (1H, s, J = 2.4 and 8, H-6ꢄ), 6.91 (1H, s, J = 2.4, H-2ꢄ), 6.97 (1H, d, J = 8,
H-5ꢄ), 6.98 (1H, d, J = 2, H-8), 7.02 (1H, dd, J = 2 and 8.8, H-6ꢄ), 7.45 (1H, d, J = 8.8, H-5ꢄ). 13C NMR (100 MHz, CD3COCD3,
20