[C:1](Cl)(=[O:5])C(Cl)=O.[C:7]1([C@H:13]([N:15]2[C:19](=[O:20])[CH2:18][C@@H:17]([C:21]([OH:23])=O)[CH2:16]2)[CH3:14])[CH:12]=[CH:11][CH:10]=[CH:9][CH:8]=1.[CH2:24]([N:26](CC)CC)C>CN(C)C=O.ClCCl>[CH3:24][N:26]([O:5][CH3:1])[C:21]([C@@H:17]1[CH2:18][C:19](=[O:20])[N:15]([C@@H:13]([C:7]2[CH:8]=[CH:9][CH:10]=[CH:11][CH:12]=2)[CH3:14])[CH2:16]1)=[O:23]Under ice-cooling, oxalyl chloride (6.54 ml, 0.075 mol) and dimethylformamide (3 drops) were added to dichloromethane solution (200 ml) of 1-[1-(R)-phenylethyl]-5-oxopyrrolidine-3-(R)-carboxylic acid (11.66 g, 0.05 mol) and stirred overnight at room temperature. After evaporation of the solvent under a reduced pressure, toluene (100 ml) was added and the solvent was again evaporated under a reduced pressure. The residue was mixed with dichloromethane (200 ml) and N,O-methylhydroxylamine hydrochloride (5.47 g, 0.055 mol), and a dichloromethane solution (50 ml) of triethylamine (17.4 ml, 0.125 mol) was added dropwise to the mixture which was stirred under ice-cooling, spending 15 minutes. This was stirred at ice-cooling for 30 minutes and then stirred at room temperature for 3 hours. The reaction solution was washed with 10% citric acid aqueous solution (100 ml), water (100 ml) and saturated sodium bicarbonate aqueous solution (100 ml) in that order and then dried over anhydrous sodium sulfate. The solvent was evaporated under a reduced pressure and the resulting residue was applied to a silica gel column chromatography. By eluting with a chloroform:methanol system of from (50:1) to (20:1), 11.32 g (82%) of the title compound was obtained as a brown oil.
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