Water → methyl 5-bromo-2-formyl-1H-pyrrole-3-carboxylate

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Reaction Conditions

Reaction Steps

POCl3 (Aldrich; 0.531 mL, 5.70 mmol) was added (dropwise, over 1 min) to DMF (1.32 mL, 17.10 mmol) under argon at 0° C., and the resulting solution was stirred at 0° C. for 15 min. This solution was then added (dropwise, over 1 min) to a dark-brown solution of methyl 5-bromo-1H-pyrrole-3-carboxylate (581 mg, 2.85 mmol) in ACN (6.0 mL) at 23° C., and the resulting solution was stirred under argon at 50° C. for 3 h. The reaction mixture was then poured into 10:1 water/sat. aq. NaHCO3 (50 mL) and extracted with DCM (3×50 mL). The combined extracts were dried over Na2SO4, filtered, and concentrated onto silica gel. Chromatographic purification (silica gel, 0-30% EtOAc/hexanes) furnished methyl 5-bromo-2-formyl-1H-pyrrole-3-carboxylate (245 mg, 1.05 mmol, 37% yield) as a white solid. 1H NMR (400 MHz, CDCl3) δ ppm 10.09 (1H, s), 9.56 (1H, br. s.), 6.72 (1H, d, J=2.7 Hz), 3.90 (3H, s). m/z (ESI, +ve) 231.9/234.1 (M+H)+.

Provenance & Evidence