Step 1: Dissolve 4,6-dichloropyrimidine (2.00 g, 13.4 mmol) and N-BOC-piperazine (3.00 g, 16.1 mmol) in 60 mL of 2-propanol and add triethylamine (4.7 mL, 33.6 mmol). The reaction mixture was heated to reflux for 2 hours. After the reaction was completed, the mixture was concentrated under reduced pressure. Dichloromethane was added to the residue and the organic layer was washed with water. The aqueous layer was back-extracted with dichloromethane and all organic layers were combined and dried over anhydrous sodium sulfate. The dried organic layer was concentrated under reduced pressure, and the crude product obtained was purified by silica gel column chromatography (eluent ratio of ethyl acetate:hexane=1:2) to afford tert-butyl 4-(6-chloropyrimidin-2-yl)piperazine-1-carboxylate (3.80 g, 95% yield) as a white solid.
