Cl[C:2]1[CH:7]=[C:6]([Cl:8])[N:5]=[CH:4][N:3]=1.[N:9]1([C:15]([O:17][C:18]([CH3:21])([CH3:20])[CH3:19])=[O:16])[CH2:14][CH2:13][NH:12][CH2:11][CH2:10]1.C(N(CC)CC)C>CC(O)C>[Cl:8][C:6]1[N:5]=[C:4]([N:12]2[CH2:11][CH2:10][N:9]([C:15]([O:17][C:18]([CH3:21])([CH3:20])[CH3:19])=[O:16])[CH2:14][CH2:13]2)[N:3]=[CH:2][CH:7]=1To a solution (60 ml) of 4,6-dichloropyrimidine (2.00 g, 13.4 mmol) and tert-butyl piperazine-1-carboxylate (3.00 g, 16.1 mmol) in 2-propanol was added triethylamine (4.7 ml, 33.6 mmol), and the mixture was heated under reflux for 2 hrs. The mixture was concentrated under reduced pressure, dichloromethane was added to the residue, and the mixture was washed with water. The aqueous layer was extracted with dichloromethane, and the combined organic layer was dried over anhydrous sodium sulfate, and concentrated under reduced pressure. The residue was purified by silica gel column chromatography (ethyl acetate:hexane=1:2) to give tert-butyl 4-(6-chloropyrimidin-2-yl)piperazine-1-carboxylate (3.80 g, yield 95%) as a white solid.
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