[CH3:1][CH:2]1[CH2:6][CH2:5][O:4][C:3]1=O.S(Cl)(Cl)=O.[CH2:12]([N:19]1[CH2:24][CH2:23][N:22]([NH2:25])[CH2:21][CH2:20]1)[C:13]1[CH:18]=[CH:17][CH:16]=[CH:15][CH:14]=1.[H-].[Na+]>C1COCC1.[Cl-].[Zn+2].[Cl-]>[CH2:12]([N:19]1[CH2:20][CH2:21][N:22]([N:25]2[CH2:5][CH2:6][CH:2]([CH3:1])[C:3]2=[O:4])[CH2:23][CH2:24]1)[C:13]1[CH:14]=[CH:15][CH:16]=[CH:17][CH:18]=1A mixture of 3-methyldihydrofuran-2(3H)-one (2.0 g), thionyl chloride (1.5 ml) and zinc chloride (10 mg) was stirred at 80° C. for 15 hours. The mixture was cooled to room temperature, and the reaction mixture was added dropwise to a solution of 4-benzylpiperazin-1-amine (3.8 g) in THF (50 mL) at 0° C., followed by stirring at 0° C. for 2 hours. Sodium hydride (60% in oil; 2.4 g) was added thereto and the mixture was stirred at room temperature for 15 hours. Ice was added thereto, and then the reaction mixture was concentrated under reduced pressure. The residue was diluted with water, and extracted with dichloromethane. The extract was dried over anhydrous sodium sulfate, and the solvent was distilled off under reduced pressure. The residue obtained was purified by basic silica gel column chromatography (ethyl acetate/hexane=1/5) to obtain the title compound (2.0 g, 37%) as a yellow oil.
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