[NH:1]1[CH2:5][CH2:4][CH:3]([OH:6])[CH2:2]1.[F:7][C:8]1[CH:9]=[C:10]([N+:15]([O-:17])=[O:16])[CH:11]=[CH:12][C:13]=1F.C(=O)([O-])[O-].[K+].[K+]>CN(C)C=O>[F:7][C:8]1[CH:9]=[C:10]([N+:15]([O-:17])=[O:16])[CH:11]=[CH:12][C:13]=1[N:1]1[CH2:5][CH2:4][CH:3]([OH:6])[CH2:2]1To a solution of 3-pyrrolidinol (1.82 g) and 3,4-difluoronitrobenzene (3.0 g) in dimethylformamide (30 ml) was added potassium carbonate (3.94 g). The mixture was stirred at room temperature overnight and then filtered followed by washing with dichloromethane. The filtrate combined was concentrated under reduced pressure. The residue obtained was chromatographed over a silica gel column eluting with ethyl acetate/hexane with increasing in the content of ethyl acetate (50% to 60%). The appropriate fractions were pooled and concentrated under reduced pressure to give the title compound (4.83 g); 1H NMR (CD3OD, 270 MHz), δ 0.85 (2H, m), 2.25-2.57 (4H, m), 3.26 (1H, m), 5.47 (1H, t, J=8.6 Hz), 6.62 (1H, dd, J=2.4, 14.0 Hz), 6.69 (1H, dd, J=2.4, 8.6 Hz).
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