[CH2:1]([O:3][C:4](=[O:11])[C:5](=O)[CH2:6][C:7](=O)[CH3:8])[CH3:2].Cl.[CH3:13][O:14][C:15]1[CH:20]=[CH:19][C:18]([NH:21][NH2:22])=[CH:17][CH:16]=1>C(O)C.O>[CH2:1]([O:3][C:4]([C:5]1[N:21]([C:18]2[CH:19]=[CH:20][C:15]([O:14][CH3:13])=[CH:16][CH:17]=2)[N:22]=[C:7]([CH3:8])[CH:6]=1)=[O:11])[CH3:2]Ethyl-2,4-dioxovalerate (0.555 g, 3.5 mmol) and 4-methoxyphenylhydrazine hydrochloride (0.67 g, 3.8 mmol) were mixed in ethanol and heated to 80° C. overnight. The reaction was cooled, diluted with water and extracted with EtOAc. Organic layers were combined and washed with water, 10% HCl, sat. NaHCO3, dried over MgSO4 and concentrated under reduced pressure. The residue was purified on silica gel (20% EtOAc in hexanes to 30% EtOAc in hexanes). Two regioisomers were isolated, the title regioisomer being the more polar (yield 492 mg). LC-MS (C14H16N2O3 calculated 260) m/z 261 (M+H).
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