[NH:1]1[CH2:6][CH2:5][NH:4][CH:3]([C:7]([OH:9])=[O:8])[CH:2]1[C:10]([OH:12])=[O:11].[Br:13][C:14]1[CH:22]=[CH:21][C:17]([C:18](Cl)=[O:19])=[CH:16][CH:15]=1.CCC1(C2C=CC(N)=CC=2)C(=O)NC(=O)CC1.C([O-])(=O)C.C1C=C2C(C(O)(O)C(=O)C2=CC=1)=O>[OH-].[Na+].C(O)(=O)C>[Br:13][C:14]1[CH:22]=[CH:21][C:17]([C:18]([N:1]2[CH2:6][CH2:5][NH:4][CH:3]([C:7]([OH:9])=[O:8])[CH:2]2[C:10]([OH:12])=[O:11])=[O:19])=[CH:16][CH:15]=1##STR11## To an ice cold solution of piperazine-2,3-dicarboxylic acid (1.74 g/0.01 mole) in aqueous sodium hydroxide (1.2 g/20 ml) was added 4-bromobenzoyl chloride (2.2 g/0.01 mole) over 30 min. The resulting solution was stirred at 0° for 2 h, then allowed to warm to room temperature overnight. The solution was applied to a column of Dowex AG-1-acetate resin and the ninhydrin positive fractions of the 3M acetic acid eluate were combined and evaporated to dryness. Recrystallization of the residue from a 50% aqueous ethanol solution yielded 4-(4-bromobenzoyl)-piperazine-2,3-dicarboxylic acid (800 mg) as a white solid m.p., 218°-20°.
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