Pyridine → Tert-butyl 4-(4-acetoxybenzoyl)piperazine-1-carboxylate

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Reaction Steps

p-Acetoxybenzoic acid (11 g, 61.1 mmol) was dissolved in methylene chloride (100 ml), to which DMF (3 drops) and thionyl chloride (5.54 ml, 76.3 mmol) were added, and the mixture was heated under reflux for 2 hours. The mixture was cooled in an ice-bath, to which a solution of tert-butyl piperazine-1-carboxylate (10.3 g, 55.5 mmol) and pyridine (12 ml, 0.15 mol) in methylene chloride (100 ml) was added dropwise, and the mixture was stirred at room temperature for 2 hours. The reaction mixture was diluted with methylene chloride, and the mixture was washed with water, 10% hydrochloric acid, saturated sodium hydrogencarbonate aqueous solution and brine, dried over magnesium sulfate, and then filtered. The filtrate was concentrated under reduced pressure. The residue was purified by silica gel column chromatography (methylene chloride/ethyl acetate=20/1) to afford tert-butyl 4-(4-acetoxybenzoyl)piperazine-1-carboxylate (18.5 g, yield 87%) as a colorless crystalline powder.

Provenance & Evidence