7295-85-4

896121-49-6

154-23-4

The general procedure for the synthesis of (2R,3S)-2-(3,4-dihydroxyphenyl)benzopyran-3,5,7-triol from 5,7-bis(benzyloxy)-2-(3,4-bis(benzyloxy)phenyl)benzodihydropyran-3-ol was carried out as follows: to a stirred 1:1 (v/v) ethyl acetate and methanol solution of 5,7-bis(benzyloxy)-2-(3,4-bis(benzyloxy)phenyl)benzodihydropyran-3-ol (0.24 mmol) at room temperature was added 10% Pd/C catalyst (0.24 mmol) in a mixed solution of ethyl acetate and methanol. alcohol (0.180 g, 0.24 mmol) was added to a slurry of 10% Pd/C catalyst (0.020 g) in a 1:1 (v/v) mixed solution of ethyl acetate and methanol (8 ml). The reaction mixture was stirred at room temperature for 1 hour, then warmed to 50-55 °C and stirred at this temperature overnight. Upon completion of the reaction, the catalyst was removed by diatomaceous earth filtration and the filtrate was concentrated on a rotary evaporator to give a light brown viscous crude product. The crude product was purified by silica gel column chromatography using 4% methanol/dichloromethane as eluent to afford the off-white powdery target product (2R,3S)-2-(3,4-dihydroxyphenyl)benzopyran-3,5,7-triol (0.045 g, 65% yield). The product was confirmed by ESIMS analysis, m/z: 291 [M+H]+.