反应详情

In 208 ml of conc. hydrochloric acid, 99.63 g of 3-(1-acetyl-4-piperidinyl)propionic acid was suspended; the suspension was stirred under refluxing conditions for six hours. The reaction mixture was then concentrated to half under reduced pressure and allowed to stand at 0° C. overnight. The crystalline precipitate was collected by filtration and washed with cold ethanol. After drying, 77.9 g of 3-(4-piperidinyl)propionic acid was obtained. Of this product, 77.5 g was dissolved in a mixture of 360 ml of dichloromethane and 400 ml of 3N sodium hydroxide aqueous solution. To the mixture, 34 ml of methyl chlorocarbonate was added dropwise at 0° C., and stirred at room temperature for five hours. After the pH of the aqueous layer was adjusted to 8 by addition of a 50% sodium hydroxide aqueous solution, the organic layer was separated and dried over anhydrous sodium sulfate. The solvent was then evaporated under reduced pressure. To the residue, isopropyl ether-hexane was added to yield 76.5 g of the title compound as colorless crystals having a melting point of 88°-90° C.

1. concentrationThe reaction mixture was then concentrated to half under reduced pressure
2. waitto stand at 0° C. overnight
3. filtrationThe crystalline precipitate was collected by filtration
4. washwashed with cold ethanol
5. customAfter drying