According to Scheme 5 Step 3: Picolinoyl chloride hydrochloride (3.68 mmol, 656 mg) and Et3N (7.37 mmol, 1.03 mL) were added to a solution of tert-butyl 4-(4-amino-2-chlorophenyl)piperazine-1-carboxylate (2.46 mmol, 766 mg) in DCM (40 mL) at 0° C. The reaction mixture was stirred at room temperature for 1 hour. The organic phase was washed with a saturated solution of NaHCO3. The aqueous phase was extracted with AcOEt. The organic phase was washed with brine, was dried over Na2SO4, was filtered and was concentrated under reduced pressure to afford tert-butyl 4-(2-chloro-4-(picolinamido)phenyl)piperazine-1-carboxylate (2.46 mmol, 1.02 g, 100%).
