Sodium hydride → Ethyl 4-chloro-1-methyl-6-(2-nitrophenoxy)-2-indolecarboxylate

After 0.42 g (1.64 mmol) of ethyl 4-chloro-6-hydroxy-1-methyl-2-indolecarboxylate was added to a suspension of 0.066 g (1.64 mmol) of 60% sodium hydride and 5 ml of dimethylformamide, the suspension was stirred at room temperature until the mixture became an almost transparent solution. Then 0.35 g (2.49 mmol) of 1-fluoro-2-nitrobenzene was added to the solution at room temperature followed by stirring for 5 hours at the same temperature. The reaction mixture was poured onto ice water. The resulting mixture was then extracted three times with ethyl acetate. The combined extracts were washed with water. After drying over anhydrous magnesium sulfate, the solvent was distilled off under reduced pressure and the residue was isolated and purified by silica gel column chromatography to give 0.53 g (94.3%) of ethyl 4-chloro-1-methyl-6-(2-nitrophenoxy)-2-indolecarboxylate.