Triethylamine → 1-Benzhydryl-4-(2,4-dimethoxycinnamoyl)piperazine hydrochloride

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Reaction Steps

In 100 ml of chloroform was suspended 25 g (120 millimoles) of 2,4-dimethoxycinnamic acid. At room temperature, 44 ml (about 600 millimoles) of thionyl chloride was added dropwise. The mixture was stirred at room temperature for 1.5 hours, and the excess of thionyl chloride and chloroform were distilled off. The residue was diluted with 200 ml of chloroform, and added dropwise at room temperature to 300 ml of of a chloroform solution of 30.2 g (120 millimoles) of benzhydrylpiperazine and 24.3 g (240 millimoles) of triethylamine. The mixture was stirred at room temperature for 3 hours, and then a 10% aqueous solution of sodium bicarbonate was added. The mixture was shaken and the organic layer was separated, washed with water, and dried over anhydrous magnesium sulfate. The solvent was distilled off under reduced pressure. The resulting oily product was diluted with 200 ml of ethanol, and 15 ml of concentrated hydrochloric acid was added. The crystals precipitated were collected by filtration. Recrystallization from hydrous methanol gave 22.7 g (yield 39.5%) of 1-benzhydryl-4-(2,4-dimethoxycinnamoyl)piperazine hydrochloride as pale yellow crystals.

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