CN1C(=O)CCC1.Cl[C:9]1[CH:14]=[N:13][C:12]([Cl:15])=[CH:11][N:10]=1.[C:16]([O:20][C:21]([N:23]1[CH2:28][CH2:27][NH:26][CH2:25][CH2:24]1)=[O:22])([CH3:19])([CH3:18])[CH3:17].C(=O)([O-])[O-].[K+].[K+]>O>[Cl:15][C:12]1[CH:11]=[N:10][C:9]([N:26]2[CH2:25][CH2:24][N:23]([C:21]([O:20][C:16]([CH3:19])([CH3:18])[CH3:17])=[O:22])[CH2:28][CH2:27]2)=[CH:14][N:13]=1
To an NMP (7.5 ml) solution of 1.51 g of 2,5-dichloropyrazine were added 2.00 g of 1-(t-butoxycarbonyl)piperazine and 2.00 g of potassium carbonate, followed by 1 hour of stirring under heating at 100° C. The mixture was cooled to room temperature, and water was added thereto, followed by extraction with ethyl acetate. The organic layer was washed with water and brine and then dried over anhydrous magnesium sulfate, and thereafter, the solvent was evaporated. The residue was purified by silica gel column chromatography (chloroform-methanol) to obtain 2.73 g of 2-chloro-5-(4-t-butoxycarbonylpiperazin-1-yl)pyrazine. Using this compound, 2-chloro-5-{4-[6-(3,4-dimethoxyphenyl)pyridine-2-carbonyl]piperazin-1-yl}pyrazine was obtained in a similar manner to Example 14 as colorless crystals.
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