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To a stirred solution of tert-butyl-4-(4-fluoro-2-(trifluoromethyl)phenyl)piperazine-1-carboxylate (6.8 g, 19.5 mmol) in anhydrous dichloromethane (90 mL) was added TFA (45 mL) dropwise at 0° C. The reaction mixture was stirred at 0° C. for 15 minutes then the cooling bath was removed and it was allowed to stir at room temperature for 2 hours. Reaction was complete as determined by TLC. Most of TFA was azeotropped with dichloroethane. The residue was then diluted with dichloromethane and washed with saturated Na2CO3 (aq.). Organic layer was dried over MgSO4. Solvent evaporation afforded 1-(4-fluoro-2-(trifluoromethyl)phenyl)piperazine in 79.9% yield (3.86 g) as light brown oil. 1H NMR (400 MHz, CHLOROFORM-D) δ ppm 2.78-2.90 (m, 4H) 2.96-3.04 (m, 4H) 7.18-7.25 (m, 1H) 7.29-7.42 (m, 2H).

1. customthe cooling bath was removed
2. stirringto stir at room temperature for 2 hours
3. customReaction
4. washwashed with saturated Na2CO3 (aq.)
5. dry with materialOrganic layer was dried over MgSO4
6. customSolvent evaporation