Toluene → 4-(2-Chloro-4-methylphenyl)piperazine-1-carboxylic acid tert-butyl ester

참여 물질

반응 단계

A mixture of 4-bromo-3-chlorotoluene (2.1 g), Boc-piperazine (1.9 g), palladium acetate (112 mg), rac-2,2′-bis(diphenylphosphino)-1,1′-binaphthyl (312 mg), sodium tert-butoxide (1.4 g) and toluene (20 mL) was refluxed for 5 hr. After cooling, water was added to the reaction mixture, and the mixture was extracted with ethyl acetate. The organic layer was washed with saturated brine, and the solvent was evaporated. The residue was purified by column chromatography (chloroform) to give 4-(2-chloro-4-methylphenyl)piperazine-1-carboxylic acid tert-butyl ester (3.1 g). To a mixture of 4-(2-chloro-4-methylphenyl)piperazine-1-carboxylic acid tert-butyl ester (932 mg), 2,4,6-trivinylcyclotriboroxane pyridine complex (1 g), palladium acetate (74 mg), 2-dicyclohexylphosphino-2′,6′-dimethoxybiphenyl (271 mg) and potassium fluoride (697 mg) was added tetrahydrofuran (4 mL), and the mixture was refluxed for 8 hr. After cooling, water was added to the reaction mixture, and the mixture was extracted with ethyl acetate. The organic layer was washed with saturated brine, and the solvent was evaporated. The residue was purified by column chromatography (chloroform) to give 4-(4-methyl-2-vinylphenyl)piperazine-1-carboxylic acid tert-butyl ester (0.9 g). 4-(4-Methyl-2-vinylphenyl)piperazine-1-carboxylic acid tert-butyl ester (0.9 g) was dissolve in chloroform (2 mL), 4N hydrogen chloride/ethyl acetate (1 mL) was added, and the mixture was stirred at room temperature for 3 hr. 1N aqueous sodium hydroxide solution (8 mL) was added, and the mixture was extracted with chloroform. The organic layer was washed with saturated brine, and the solvent was evaporated to give 1-(4-methyl-2-vinylphenyl)piperazine (606 mg). 1-(4-Methyl-2-vinylphenyl)piperazine (606 mg) was dissolved in tetrahydrofuran (8 mL), 4-iodobenzoyl chloride (1.1 g) and 1N aqueous sodium hydroxide solution (4 mL) were added, and the mixture was stirred at room temperature overnight. The mixture was extracted with ethyl acetate, washed with saturated brine, and the solvent was evaporated. The residue was purified by column chromatography (chloroform) to give the title compound (1 g).

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