Acetic Acid → 1-Cyclopropylmethyl-4-[4-pyridin-2-yl-2-(3,3,5,5-tetramethylcyclohexyl)phenyl]piperazine

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Reaction Steps

To a mixture of 1-[4-pyridin-2-yl-2-(3,3,5,5-tetramethylcyclohexyl)phenyl]piperazine (10 mg, 0.026 mmol) produced in Example (10b), cyclopropanecarbaldehyde (0.004 mL, 0.054 mmol) and tetrahydrofuran (2 mL) were added sodium triacetoxyborohydride (14 mg, 0.066 mmol) and acetic acid (0.002 mL, 0.035 mmol) in that order, followed by stirring for 40 minutes at room temperature. Ethyl acetate, saturated aqueous sodium hydrogencarbonate and water were added to the reaction mixture and extraction was performed with ethyl acetate. The separated organic layer was concentrated by blowing nitrogen. The resultant residue was purified by NH silica gel column chromatography (ethyl acetate/hexane) to give 1-cyclopropylmethyl-4-[4-pyridin-2-yl-2-(3,3,5,5-tetramethylcyclohexyl)phenyl]piperazine. This compound was dissolved in dichloromethane, and a 4N solution of hydrogen chloride in ethyl acetate was added. The solution was concentrated by blowing nitrogen gas, and diethyl ether was added to the obtained residue to produce a solid. After triturating the solid by sonication, the supernatant diethyl ether solution was removed. The solid residue was dried by blowing nitrogen, to give 3 mg of the title compound as a light yellow solid.

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