A solution of 1.08 g (4.82 mmol) of 2-dimethylamino-5-fluoro-6-methoxybenzo[b]thiophene (Part B) in 15 mL of chlorobenzene was treated with 0.99 g (5.31 mmol) of 4-nitrobenzoyl chloride. The reaction was stirred at room temperature for 17 h and was diluted with 100 mL of EtOAc. The solution was washed sequentially with 2 N aqueous NaOH (2×50 mL), H2O (50 mL) and brine (50 mL), then dried over Na2SO4, and filtered. Evaporation of the solvent in vacuo afforded 2.1 g of a dark solid which was purified by flash chromatography (SiO2; gradient of 10% then 20% then 40% EtOAc in hexanes) to give 0.27 g of starting material and 1.25 g (3.34 mmol; 93% based on consumed starting material) of the title compound.
