[F:1][C:2]1[CH:7]=[CH:6][C:5]([CH3:8])=[C:4]([N+:9]([O-:11])=[O:10])[CH:3]=1.[N+:12]([O-])([OH:14])=[O:13]>S(=O)(=O)(O)O>[F:1][C:2]1[CH:7]=[C:6]([N+:12]([O-:14])=[O:13])[C:5]([CH3:8])=[C:4]([N+:9]([O-:11])=[O:10])[CH:3]=1Fuming sulphuric acid (105 mL) was added dropwise to 4-fluoro-1-methyl-2-nitrobenzene (30 g, 0.194 mol) at −5° C. 0° C. and a mixture of fuming sulphuric acid (54 mL) and fuming nitric acid (18 mL) was added dropwise to it at −5° C. 0° C. over the period of 3 h. After complete addition, the reaction mixture was stirred for 3 hours at ambient temperature. TLC showed complete conversion of starting material to the product. The reaction mixture was poured into ice and extracted with dichloromethane. The combined organic layers was washed with water (600 mL), sat. sodium bicarbonate (600 mL) and brine (600 mL). It was dried over anhydrous magnesium sulfate and concentrated under reduced pressure to give the crude product, which was purified by silica gel column chromatography (PE: EA=20:1) to afford the title compound.
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