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In a two-necked round-bottomed flask equipped with an argon inlet, 4.0 g (28.8 mmol) of ethyl pyrrole-2-carboxylate was dissolved in 100 mL of 1,2-dichloroethane. Subsequently, 8.0 g of anhydrous aluminum trichloride was slowly added. Next, 4.4 mL (62 mmol) of acetyl chloride dissolved in 50 mL of 1,2-dichloroethane was added dropwise over 15 minutes. The reaction mixture was stirred at room temperature for 1 hour and then carefully poured into 200 g of crushed ice for hydrolysis. The mixture was transferred to a separatory funnel and the organic phase was separated. The aqueous phase was extracted with dichloromethane (2 × 200 mL) and the combined organic phases were washed sequentially with saturated aqueous sodium bicarbonate (1 × 100 mL) and deionized water (1 × 100 mL). The organic phase was dried over anhydrous magnesium sulfate and concentrated under reduced pressure to remove the solvent. Purification by silica gel column chromatography (eluent: dichloromethane solution containing 1% methanol) afforded 4.0 g (76% yield) of the target product ethyl 4-acetyl-1H-pyrrole-2-carboxylate as a light brown powder.

[1] Heterocycles, 1988, vol. 27, # 8, p. 1855 - 1860
[2] Chemical and Pharmaceutical Bulletin, 1996, vol. 44, # 1, p. 48 - 54
[3] Patent: US2003/229131, 2003, A1. Location in patent: Page 24