[CH3:1][O:2][C:3]1[C:17]([O:18][CH3:19])=[CH:16][CH:15]=[CH:14][C:4]=1[CH2:5][CH:6]1[NH:11][C:10](=O)[CH2:9][NH:8][C:7]1=O.COCCOC.[H-].[Al+3].[Li+].[H-].[H-].[H-]>O1CCCC1>[CH3:1][O:2][C:3]1[C:17]([O:18][CH3:19])=[CH:16][CH:15]=[CH:14][C:4]=1[CH2:5][CH:6]1[CH2:7][NH:8][CH2:9][CH2:10][NH:11]1A suspension of 3-(2,3-dimethoxybenzyl)-2,5-piperazinedione (1.26 g) in a mixed solvent of tetrahydrofuran (50 ml) and 1,2-dimethoxyethane (50 ml) was heated at 60° C. with stirring and lithium aluminum hydride (0.905 g) was added thereto portionwise carefully. After the reaction mixture was heated at 70° C. with stirring for 3 hours, lithium aluminum hydride (0.20 g) and tetrahydrofuran (30 ml) were added thereto again and the suspension was stirred at the same temperature for 12 hours. After being cooled with ice-water, the mixture was quenched by sequential addition of water (1.3 ml), 15% aqueous sodium hydroxide (1.3 ml), water (3.8 ml) and the whole was stirred at room temperature for 2 hours. The resulting insoluble materials were removed by filtration and the filtrate was dried over sodium sulfate, and evaporated under reduced pressure to give light yellowish oil of 2-(2,3-dimethoxybenzyl)piperazine (0.97 g).
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