[CH3:1][C:2]1[CH2:3][CH:4]([CH:9]2[CH2:14][CH2:13][N:12]([C:15]([O:17][CH2:18][C:19]3[CH:24]=[CH:23][CH:22]=[CH:21][CH:20]=3)=[O:16])[CH2:11][CH2:10]2)[C:5](=[O:8])[NH:6][N:7]=1>C(#N)C.[Cu](Cl)Cl>[CH3:1][C:2]1[CH:3]=[C:4]([CH:9]2[CH2:14][CH2:13][N:12]([C:15]([O:17][CH2:18][C:19]3[CH:20]=[CH:21][CH:22]=[CH:23][CH:24]=3)=[O:16])[CH2:11][CH2:10]2)[C:5](=[O:8])[NH:6][N:7]=1Copper(II) chloride (anhydrous; 2.02 g, 15.05 mmol) was added to a solution of benzyl 4-(6-methyl-3-oxo-2,3,4,5-tetrahydropyridazine-4-yl)piperidine-1-carboxylate (2.48 g, 7.53 mmol) in acetonitrile (26 mL). The reaction mixture was heated at 90° C. After 18 h, the mixture was cooled to ambient temperature and concentrated. The residue was diluted with dichloromethane and 1 N HCl. The mixture was extracted with dichloromethane (3×), and the combined organic extracts were dried over magnesium sulfate and concentrated. Purification by silica gel chromatography (100% dichloromethane→90% dichloromethane/methanol) to give the title compound (1.45 g). MS 328.2 (M+1).
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