18761-31-4

77123-61-6

18761-31-4

Step 1c. Synthesis of 5-nitrobenzofuran (Compound 104): a mixture of (2-fluoro-5-nitrophenyl)ethynyltrimethylsilane (Compound 103, 7.30 g, 30.8 mmol), sodium acetate (10.1 g, 123 mmol), and N,N-dimethylformamide (70 mL) was stirred and reacted for 16 hours at 100 °C. After completion of the reaction, the precipitate was collected by filtration and washed with N,N-dimethylformamide. The filtrates were combined and the solvent was removed by evaporation to give the crude product. The crude product was purified by short silica gel column chromatography (eluent: ethyl acetate/petroleum ether=1/10) to afford the title compound 104 as a brown solid (3.0 g, 60% yield).