[C:1]([O:8][CH3:9])(=[O:7])[CH2:2][CH2:3][C:4]([O-])=[O:5].C1N=CN(C(N2C=NC=C2)=O)C=1.O/[N:23]=[C:24](\[NH2:32])/[CH2:25][C:26]1[CH:31]=[CH:30][CH:29]=[CH:28][CH:27]=1>CN(C=O)C>[CH2:25]([C:24]1[N:32]=[C:4]([CH2:3][CH2:2][C:1]([O:8][CH3:9])=[O:7])[O:5][N:23]=1)[C:26]1[CH:31]=[CH:30][CH:29]=[CH:28][CH:27]=1Butanedioic acid, monomethyl ester (4.0 g, 30.3 mmole) and CDI (5.40 g, 33.3 mmole) were dissolved in anhydrous DMF (15 ml) and stirred at room temperature for 3 hours. (1Z)-N′-hydroxy-2-phenylethanimidamide (5.0 g, 33.3 mmole) was added to above solution and the mixture was stirred at 90° C. for 20 hours. The reaction mixture was concentrated and the residue was diluted with water and EtOAc. The organic layer was washed with water and brine, dried over Na2SO4, filtered and concentrated. The residue was purified by flash chromatography (elution with 1:3 ethyl acetate:hexane) to give the desired product as light yellowish oil (5.2 g, 70% yield). LCMS calculated for C13H15N2O3 (M+H): 247.1. found: 247.1.
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