Chlorosuccinimide → 2-Chloro-6H-thieno[2,3-b]pyrrole-5-carboxylic acid ethyl ester

Participants

Reaction Steps

Using a modified procedure by R. M. Kellogg et al. (J. Org. Chem., 33: 2902-290 (1968)), to a 0° C. solution of 6H-thieno[2,3-b]pyrrole-5-carboxylic acid ethyl ester (Eras, J.; Galvez, C.; Garcia, F., J. Heterocycl. Chem., 21: 215-217 (1984); 1.45 g, 7.44 mmol) in acetic acid (15 mL) and CHCl3 (15 mL) was added N-chlorosuccinimide (1.04 g, 7.81 mmol) over 2 h. The reaction mixture was slowly allowed to warm to room temperature over several hours, stirred overnight, concentrated to remove the chloroform, diluted with water, basified with 5 N NaOH, and extracted with ethyl acetate. The combined organic phases were washed with saturated aqueous NaHCO3, dried over MgSO4, and concentrated. The product was purified by chromatron chromatography (radial) using 90:10 hexanes/diethyl ether and then then then the product obtained was recrystallized using hexanes/diethyl ether (90:10). Last, the product of the recrystallization was further purified by flash column chromatography using 90:10 petroleum ether/isopropyl ether. The resulting product was obtained as a white solid (824 mg, 48%).

Provenance & Evidence