5,7-Dihydrox -4'-methoxyisoflavone synthesis

15485-66-2

68-12-2

491-80-5

The general procedure for the synthesis of 5,7-dihydroxy-3-(4-methoxyphenyl)-4H-benzopyran-4-one from 2-(4-methoxyphenyl)-1-(2,4,6-trihydroxyphenyl)ethanone and N,N-dimethylformamide was carried out as follows: ethyl ether boron trifluoride (3 mL, 24 mmol) was added dropwise to 3 mL anhydrous N,N-dimethylformamide containing 8 mmol of 2-(4-methoxyphenyl)-1-(2,4,6-trihydroxyphenyl)ethanone (2,4,6-trihydroxyphenyl)acetonide, under the conditions of cooling in ice bath and vigorous stirring. 2-(4-methoxyphenyl)-1-(2,4,6-trihydroxyphenyl)ethanone to 3 mL of anhydrous N,N-dimethylformamide. After stopping the cooling, trichlorophosphorus (0.9 mL, 9.6 mmol) was added slowly and dropwise. After all components were mixed well, the reaction mixture was stirred at 60-70°C for 2 hours. After completion of the reaction, the mixture was poured into acidified water and the precipitate was filtered out. The crude product was purified by column chromatography using hexane and ethyl acetate (8:2, v/v) as eluents to afford the target compound 5,7-dihydroxy-3-(4-methoxyphenyl)-4H-benzopyran-4-one (a) in 61% yield with a melting point of 212-214 °C. Elemental analysis (C16H12O5) Calculated values: C, 67.60; H, 4.25; O, 28.14; measured values: C, 67.57; H, 4.27; O, 28.15.1H NMR (DMSO-d6, 400 MHz): δ 12.94 (s, 1H, 5-OH), 10.92 (s, 1H, 7-OH), 8.38 ( s, 1H, 2-H), 7.50 (d, J = 8.0 Hz, 2H, Ar-H), 7.0 (d, J = 8.0 Hz, 2H, Ar-H), 6.40 (s, 1H, Ar-H), 5.77 (s, 1H, Ar-H), 3.79 (s, 3H, OCH3).13C NMR (DMSO-d6, 100 MHz): δ 180.0, 164.3, 161.9, 159.17, 157.5, 154.2, 130.1, 122.9, 121.9, 113.7, 104.4, 99.0, 93.6, 55.1. ESI-MS: m/z 285 [M + H]+. FT-IR (KBr, cm-1): 3312 (O-H), 3007 (C-H aromatic), 3007 (C-H aromatic), 3007 (C-H aromatic). 3007 (C-H aromatic), 2950 (C-H aliphatic), 1642 (C=O).