[NH:1]1[CH2:5][CH2:4][CH2:3][C:2]1=[O:6].[H-].[Na+].[F:9][C:10]1[CH:11]=[C:12]([N+:17]([O-:19])=[O:18])[CH:13]=[CH:14][C:15]=1F>CN(C=O)C>[F:9][C:10]1[CH:11]=[C:12]([N+:17]([O-:19])=[O:18])[CH:13]=[CH:14][C:15]=1[N:1]1[CH2:5][CH2:4][CH2:3][C:2]1=[O:6]To 468 mg (5.5 mmol) of 2-pyrrolidone (Fluka, Buchs, Switzerland) in 10 ml of DMF at 0° C. are added 240 mg (5.5 mmol) of 55% NaH in oil. The reaction mixture is stirred for 30 min at 0° C. and for 30 min at rt. After this time, 795 mg (5 mmol) of 3,4-difluoronitrobenzene (Aldrich, Buchs, Switzerland) are added and the reaction mixture is stirred for 1 h at rt. The reaction mixture is quenched with 1 M aqueous HCl and extracted with EtOAc (2×). The organic layers are washed with aqueous sat. NaHCO3 and with brine (3×), dried over MgSO4, filtered and evaporated. The residue is purified by flash chromatography on silica gel (hexane-EtOAc 5:1 to 1:3) to give the title compound as a solid. ES-MS: 225 (M+H)+; analytical HPLC: tret=2.99 minutes (Grad 1).
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