反应详情

Cyclopentanol (7.7 ml, 85 mmol) and triphenylphosphine (28 g, 107 mmol) were added to a solution of (4-hydroxy-3-methyoxy-phenyl)-acetic acid methyl ester (14 g, 71 mmol) in tetrahydrofuran (280 ml) under nitrogen at 0° C. Diethylazodicarboxylate (15.7 ml, 100 mmol) was then added dropwise and the reaction was allowed to warm to room temperature and stirred for 44 hours. The solvent was removed under reduced pressure, pentane (200 ml) was added and the suspension was filtered. The filtrate was concentrated under reduced pressure and purified by flash column chromatography on silica gel eluting with a solvent gradient of cyclohexane:ethyl acetate (90:10 changing to 85:15, by volume) to give (4-cyclopentyloxy-3-methoxy-phenyl)-acetic acid methyl ester (12.4 g) as a colourless oil. 1H NMR (400 MHz, CD3OD): δ=6.79-6.85 (2H, m), 6.73-6.79 (1H, d), 4.73-4.79 (1H, brs), 3.79 (3H, s), 3.64 (3H, s), 3.53 (2H, s), 1.74-1.89 (6H, m), 1.56-1.67 (2H, m) ppm. LRMS (electrospray): m/z [M+Na]+ 287. Anal. Found C, 68.01; H, 7.74. C15H20O4 requires C, 68.16; H, 7.63%.

1. customThe solvent was removed under reduced pressure, pentane (200 ml)
2. additionwas added
3. filtrationthe suspension was filtered
4. concentrationThe filtrate was concentrated under reduced pressure
5. custompurified by flash column chromatography on silica gel eluting with a solvent gradient of cyclohexane:ethyl acetate (90:10 changing to 85:15, by volume)