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Part A: 4-(4-bromophenyl)piperidine (960 mg, 4.0 mmol) was mixed with di-tert-butyl dicarbonate (960 mg, 4.4 mmol) in dichloromethane (DCM, 10 mL) at 0 °C. The reaction was completed by LC-MS analysis. After confirming the completion of the reaction by LC-MS analysis, additional dichloromethane (10 mL) was added to dilute the reaction mixture. Subsequently, the reaction mixture was washed with 1N HCl (10 mL) to remove unreacted feedstock and by-products. The organic phase was dried with anhydrous magnesium sulfate, filtered and concentrated. The crude product was purified by fast column chromatography using gradient elution (0 to 100% hexane/ethyl acetate) conditions to afford the target compound 1-N-Boc-4-(4-bromophenyl)piperidine (Compound 2) as a white solid (1.36 g, 100% yield). HPLC-MS analysis showed retention time t R = 2.50 min (UV detection wavelength 2*nm), the The mass calculated value was C16H22BrNO2[M+H]+ 339.1 and the actual observed LCMS m/z was 284.1 (M+H-tBu).

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