[NH2:1][C:2]1[C:6]([C:7]([O:9][CH2:10][CH3:11])=[O:8])=[CH:5][N:4]([CH3:12])[N:3]=1.C([Li])CCC.F[C:19]1[CH:24]=[CH:23][C:22]([F:25])=[CH:21][C:20]=1[N+:26]([O-:28])=[O:27].Cl>O1CCCC1>[F:25][C:22]1[CH:23]=[CH:24][C:19]([NH:1][C:2]2[C:6]([C:7]([O:9][CH2:10][CH3:11])=[O:8])=[CH:5][N:4]([CH3:12])[N:3]=2)=[C:20]([N+:26]([O-:28])=[O:27])[CH:21]=1A solution of ethyl 3-amino-1-methylpyrazole-4-carboxylate (Helv. Chim. Acta (1959) 42 349)(17 g) in dry tetrahydrofuran (250 ml) was stirred under nitrogen at -10° C. n-Butyl lithium (75 ml of 1.84 molar solution in hexane) was added at -10° to -15° C. The mixture was stirred at -15° C. for 10 minutes and a solution of 2,5-difluoronitrobenzene (16 g) in dry tetrahydrofuran (50 ml) was added at -15° to -10° C. The solution was warmed to room temperature and stirred for 1 hour. The ink-blue solution was poured into 500 ml of a 1:1 mixture of hydrochloric acid (2M) and ice-brine, extracted with chloroform (3×250 ml), washed with water (2×250 ml), dried with magnesium sulphate and evaporated to dryness. The brick-red residue was crystallised from ethanol (800 ml) to give the title compound having a m.p. of 162° C.
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