3-Fluoro-4-nitrophenol (75 g, 0.48 mol) was dissolved in acetone (700 mL) and cooled in an ice water bath. Subsequently, 1,8-diazabicyclo[5,4,0]undec-7-ene (145 g, 0.96 mol) was added slowly over about 1 hour and the reaction was held for 5 minutes. Next, iodomethane (135 g, 0.96 mol) was added dropwise over 10 min. The reaction mixture was stirred at room temperature for 16 hours. After that, 1,8-diazabicyclo[5,4,0]undec-7-ene (73 g, 0.48 mol) and iodomethane (68 g, 0.48 mol) were added and the mixture was heated to 50 °C and maintained for 1 hour. After completion of the reaction, the solid insoluble material was removed by filtration and the filtrate was concentrated and mixed with ethyl acetate and 1 M hydrochloric acid. The organic layer was washed sequentially with hydrochloric acid and aqueous sodium bicarbonate, concentrated and precipitated as a solid by stirring in a hexane solution of 1% ethyl acetate. Finally, the product 3-fluoro-4-nitroanisole (72 g, 88% yield) was collected and air dried.
