C(OC(=O)[N:7]([CH2:17][C:18]1[CH:23]=[CH:22][C:21]([F:24])=[CH:20][CH:19]=1)[C:8]1[CH:9]=[N:10][CH:11]=[CH:12][C:13]=1[N+:14]([O-])=O)(C)(C)C.[CH3:26][C:27]([Mg]Br)=[CH:28][CH3:29].[Cl-:32].[NH4+]>O1CCCC1>[ClH:32].[F:24][C:21]1[CH:20]=[CH:19][C:18]([CH2:17][NH:7][C:8]2[C:13]3[NH:14][C:28]([CH3:29])=[C:27]([CH3:26])[C:12]=3[CH:11]=[N:10][CH:9]=2)=[CH:23][CH:22]=1(4-Fluorobenzyl)-(4-nitropyridin-3-yl)-carbamic acid tert-butyl ester (5.1 g) prepared in Step 2 was dissolved in anhydrous tetrahydrofuran (100 ml) under a nitrogen atmosphere. 1-Methyl-1-propenyl magnesium bromide (0.5M in tetrahydrofuran solution, 55.0 ml, 65.2 mmol) was added at −78° C. to the solution, which was then stirred for 5 hours at −20° C. 20 ml of 20% ammonium chloride solution was added to the reaction mixture, which was then extracted with ethyl acetate (200 ml) twice. The separated organic layer was dried on anhydrous magnesium sulfate and concentrated under reduced pressure. The resulting residue was purified with silica gel column chromatography (ethyl acetate/methanol=10/1 (v/v)), dissolved in 1 ml of ethyl acetate and then saturated with hydrochloric acid gas. The resulting precipitate was filtered to give the titled compound as a pale yellow solid (2.1 g, 35.0%).
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