4-Formylbenzoic acid → 4-(4-Cyclopropyl-piperazine-1-carbonyl)-benzaldehyde

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Reaction Conditions

Reaction Steps

A mixture of 4-formyl-benzoic acid (54.4 g), toluene (500 mL), DMF (3.6 mL), and thionyl chloride (30.4 mL) was heated at 60° C. for 2 h and then was cooled to 5° C. In a separate flask, a 5° C. mixture of NaOH (50.7 g), water (550 mL), and toluene (150 mL) was treated with 1-cyclopropyl-piperazine dihydrochloride (70.0 g) in portions while the temperature was maintained below 10° C. After the addition was complete, the mixture was cooled to 5° C. and treated with the crude acyl chloride solution prepared as above at a rate such that the temperature did not exceed 10° C. After the addition was complete, the mixture was allowed to warm to room temperature and was stirred overnight. The biphasic mixture was basified to pH˜10 with 1 N NaOH (300 mL). The layers were separated and the aqueous layer was extracted with toluene (100 mL×2). The combined organic layers were washed with brine (200 mL), dried (Na2SO4), and concentrated to yield the title compound as pale yellow viscous oil.

Provenance & Evidence