C([N:4]1[CH2:9][C:8](=[O:10])[NH:7][C:6](=[CH:11][C:12]2[CH:17]=[CH:16][C:15]([C:18]([F:21])([F:20])[F:19])=[C:14]([O:22][CH3:23])[CH:13]=2)[C:5]1=[O:24])(=O)C>O1CCCC1.[C].[Pd]>[CH3:23][O:22][C:14]1[CH:13]=[C:12]([CH:17]=[CH:16][C:15]=1[C:18]([F:21])([F:20])[F:19])[CH2:11][CH:6]1[NH:7][C:8](=[O:10])[CH2:9][NH:4][C:5]1=[O:24]A solution of 1-acetyl-3-[[3-methoxy-4-(trifluoromethyl)phenyl]methylene]piperazine-2,5-dione (1.8 g) in tetrahydrofuran (50 ml) was hydrogenated over 10% palladium-carbon (50% wet, 180 mg) for 5 hours at atmospheric pressure. After removal of the catalyst by filtration, the filtrate was added hydrazine monohydrate (395 mg). The mixture was stirred for 1.5 hours at room temperature and concentrated under reduced pressure. The residue was triturated with isopropyl ether (12 ml) and the precipitates were collected by filtration, and washed with isopropyl ether to give 3-[3-methoxy-4-(trifluoromethyl)benzyl]piperazine-2,5-dione (1.29 g) as a powder.
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