Sodium Hydroxide → ethyl 3-bromo-4-chloro-5-methyl-1H-pyrrole-2-carboxylate

Ethyl 4-chloro-5-methyl-1H-pyrrole-2-carboxylate (Intermediate 7, 300 mg, 1.6 mmol) was dissolved in dry dichloromethane (10 ml), N-bromosuccinimide (285 mg, 1.6 mmol) was added at 0° C. and resulting mixture was stirred at room temperature over night. The mixture was poured into cold sodium hydroxide aqueous solution (2M) (20 ml), extracted with diethyl ether (2×20 ml). The organic phase was then washed with water (20 ml) and brine (20 ml), dried over anhydrous sodium sulfate, concentrated and purified by column chromatography (hexanes/ethyl acetate, gradient) to give the desired product as a yellowish solid. (424 mg).