[Synthesis]
Compound 1 (CAS: 119249-30-8, 150 mg, 0.25 mmol) was dissolved in a mixture of methanol (20 mL) and 30% ammonia (5 mL) under stirring conditions. The reaction mixture was stirred continuously for 12 hours at room temperature. Upon completion of the reaction, the solvent was removed by distillation under reduced pressure. The resulting residue was purified by silica gel column chromatography using ethyl acetate/methanol (3:1, v/v) as eluent to afford the target product 5-hydroxy-2-(4-hydroxyphenyl)-7-(((2S,3R,4S,5S,6R)-3,4,5-trihydroxy-6-(hydroxymethyl)tetrahydro-2H-pyran-2-yl)oxy)-4H-benzopyran-4-one , a yellow solid (78 mg, 72% yield). The melting point of the product was 234-236°C (literature value: 238-239°C). The infrared spectrum (KBr pressed sheet, cm^-1 ) showed characteristic absorption peaks: 3440, 2918, 1615, 1563, 1452, 1346, 1273, 1245, 1146, 1103, 1072, 1024, 895. the NMR hydrogen spectrum (400 MHz, DMSO-d6) δ: 12.97 (s, 1H, OH-5), 10.48 (s, 1H, OH-5), 10.47 (s, 1H). 10.48 (s, 1H, OH-4'), 7.96 (d, J = 8.8 Hz, 2H, H-2', H-6'), 6.94 (d, J = 8.8 Hz, 2H, H-3', H-5'), 6.87 (s, 1H, H-3), 6.83 (d, J = 1.6 Hz, 1H, H-8), 6.45 (d, J = 1.6 Hz, 1H, H-6), 6.45 (d, J = 1.6 Hz, 1H, H-8), 6.45 (d, J = 1.6 Hz, 1.6 Hz, 1.6 Hz), 6.85 (d, J = 1.6 Hz, 1.6 Hz, 1.6 Hz, 1.6 Hz, 1.6 Hz). 1H, H-6), 5.42 (d, J = 8.0 Hz, 1H, H-1), 5.15 (s, 1H, OH-2), 5.08 (s, 1H, OH-3), 5.06 (s, 1H, OH-4), 4.63 (s, 1H, OH-6), 3.72-3.70 (m, 1H, H-2), 3.49-3.18 (m, 5H H-3,4,5,6). NMR carbon spectrum (100 MHz, DMSO-d6) δ: 60.6, 69.6, 73.1, 76.5, 77.2, 94.8, 99.6, 99.9, 103.1, 105.4, 116.0, 121.1, 128.6, 156.9, 161.1, 161.4, 163.0, 164.3, 180.1. The calculated value of [M + Na]+ C21H20O10Na by high resolution mass spectrometry (HRMS) was 455.3665 and the measured value was 455.3649. |