反应详情

(2-Carboxyethyl)triphenylphosphonium bromide (150 g, 361 mmol) was suspended in tetrahydrofuran (500 mL) and 2,4-dimethylbenzaldehyde (55.4 mL, 397 mmol) was added thereto. A solution of potassium t-butoxide (81.1 g, 722 mmol) in tetrahydrofuran (300 mL) was added thereto under nitrogen atmosphere over 10 minutes and the mixture was stirred under ice-cooling for 3 hours. Water was added to the reaction mixture to stop the reaction and the temperature of the liquid was returned to room temperature. The mixture was concentrated under reduced pressure, a 8N aqueous sodium hydroxide solution was added thereto to bring pH to 11 and ether was added thereto to separate it. A 12N aqueous hydrochloric acid solution was added to an aqueous phase to bring pH to 2 and ethyl acetate was added thereto to separate it. The thus obtained organic phase was separated, washed with water and a saturated aqueous NaCl solution and dried over anhydrous magnesium sulfate. After filtration, the solvent was evaporated under reduced pressure and the residue was purified by silica gel chromatography (hexane:ethyl acetate, 10:1-6:1) to obtain 4-(2,4-dimethylphenyl)-3-butenoic acid (37.0 g, yield: 54%). 10% Palladium-carbon (7.96 g, 50% hydrous) was added to a solution of the obtained 4-(2,4-dimethylphenyl)-3-butenoic acid (37.0 g, 195 mmol) in methanol (400 mL) and the mixture was stirred at room temperature under a hydrogen atmosphere for 3 hours. After the palladium-carbon in the reaction mixture was Celite-filtered, the filtrate was evaporated under reduced pressure. The residue was purified by silica gel chromatography (hexane:ethyl acetate, 10:1) to obtain the title compound (64.4 g, yield: 84%).

1. temperaturecooling for 3 hours
2. customthe reaction
3. customwas returned to room temperature
4. concentrationThe mixture was concentrated under reduced pressure
5. additiona 8N aqueous sodium hydroxide solution was added
6. additionwas added
7. customto separate it
8. additionA 12N aqueous hydrochloric acid solution was added to an aqueous phase
9. additionwas added
10. customto separate it
11. customThe thus obtained organic phase was separated
12. washwashed with water
13. dry with materiala saturated aqueous NaCl solution and dried over anhydrous magnesium sulfate
14. filtrationAfter filtration
15. customthe solvent was evaporated under reduced pressure
16. customthe residue was purified by silica gel chromatography (hexane:ethyl acetate, 10:1-6:1)