To a mixture of 4-bromo-6-fluoro-1H-indole (2 g) in DMF (5 ml) was added sodium hydride (60% in mineral oil) (0.448 g). The reaction was stirred at 20° C. for 10 min. 4-Nitrobenzenesulfonyl chloride (2.278 g) was added and the reaction was stirred at 20° C. for 1 h. The mixture was poured onto water (100 ml), and extracted with DCM (50 ml) which was separated by hydrophobic frit. Purification by silica (2×100 g) on Flashmaster II using a gradient of DCM and cyclohexane gave the title compound as a pale yellow solid, 1.54 g.
