4-Piperidinecarboxylic acid → 1-Acetyl-4-(2-hydroxy-5-methoxybenzoyl)piperidine

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Reaction Steps

To a stirred mixture of 60.0 g of isonipecotic acid and 290 ml of 1,2-dichloromethane, at 40°, was added dropwise, 27 ml of thionyl chloride, dissolved in 27 ml of dichloroethane. After 50% of the thionyl chloride had been added, the temperature was raised to 65°. After complete addition of the thionyl chloride, the reaction mixture was stirred at 65° for 1 hr. The reaction mixture was cooled to 20° and 48.6 g of 1,4-dimethoxybenzene was added, followed by the slow addition of 93.6 g of aluminum chloride. The solution was heated under reflux for 4 hrs, the dichloroethane was decanted from the insoluble complex, and concentrated hydrochloric acid was added. The acid hydrolysate was added to the dichloroethane solution and the mixture was extracted three times with chloroform. The organic extract was washed with water, dried over anhydrous magnesium sulfate and the solvent was removed in vacuo to give an oil. The oil was scratched with a glass rod until crystallization was effected. The solid was collected to yield 87.0 g of product. Recrystallization twice from isopropyl ether gave an analytically pure product, mp, 93°-94°.

Provenance & Evidence