[C:1]([NH:4][NH2:5])(=[O:3])[CH3:2].C(N(CC)CC)C.Cl[C:14](=[O:20])[C:15]([O:17][CH2:18][CH3:19])=[O:16].C(OCC)(=O)C>C(Cl)Cl>[C:1]([NH:4][NH:5][C:14](=[O:20])[C:15]([O:17][CH2:18][CH3:19])=[O:16])(=[O:3])[CH3:2]To a solution of acetohydrazide (36.0 g, 486 mmol) in CH2Cl2 (250 mL) stirring at 0° C. under N2, was added triethylamine (250 mL, 1.46 mol) followed by ethyl chlorooxoacetate (65.0 mL, 584 mmol) over 1 h. The reaction mixture was stirred at rt for 8 h at which time ethyl acetate was added and the salts were removed by filtration. The filtrate was concentrated in vacuo and the residue purified by column chromatography using a gradient of 5-15% EtOAc/hexane to afford the product as an off-white solid (40.0 g, 47%). 1H NMR (300 MHz, CDCl3): δ 9.85 (1H, bs), 9.29 (1H, bs), 4.35 (2H, q, J=7 Hz), 2.10 (3H, s), 1.36 (3H, t, J=7 Hz). MS (M+H): 175.0.
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