反应详情

To a mixture of 3-oxopiperazine-1-carboxylic acid tert-butyl ester (5 g), 1-bromo-2,4-dimethylbenzene (3.4 mL), potassium carbonate (10.6 g) and copper (I) iodide (952 mg) were added toluene (25 mL) and N,N′-dimethylethylenediamine (1.1 mL), and the mixture was refluxed for 8 hr. After cooling, water was added to the reaction mixture, and the mixture was extracted with chloroform. The organic layer was washed with saturated brine, and the solvent was evaporated. The residue was purified by column chromatography (chloroform:methanol) to give 4-(2,4-dimethylphenyl)-3-oxopiperazine-1-carboxylic acid tert-butyl ester. The obtained 4-(2,4-dimethylphenyl)-3-oxopiperazine-1-carboxylic acid tert-butyl ester was dissolved in chloroform (10 mL), 4N hydrogen chloride/ethyl acetate (10 mL) was added, and the mixture was stirred at room temperature for 3 hr. The precipitate was collected by filtration to give 1-(2,4-dimethylphenyl)piperazin-2-one hydrochloride (3 g).

1. filtrationThe precipitate was collected by filtration