1H-Pyrrolo(2,3-b)pyridine → 3-Fluoro-5-nitrobenzoyl chloride

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Reaction Steps

3-fluoro-5-nitrobenzoic acid (2.90 g, 10.8 mmol) was dissolved in thionyl chloride (20.0 mL) and the reaction was heated to reflux overnight. The reaction was cooled and was concentrated to provide a white solid which was dried under vacuum overnight. Compound 2 (512 mg, 4.33 mmol) was dissolved in methylene chloride (10.0 mL), under an atmosphere of argon and aluminum trichloride (2.85 g, 21.4 mmol) was added. The reaction was stirred at room temperature for 1 hour. The 3-fluoro-5-nitrobenzoyl chloride formed above was dissolved in methylene chloride (10.0 mL) and was added to the reaction. The reaction was stirred at room temperature overnight. The reaction was quenched with methanol and concentrated under reduced pressure. The resulting solid was extracted with ethyl acetate and saturated sodium bicarbonate. The organic portion was dried with anhydrous magnesium sulfate, adsorbed onto silica and purified by silica gel flash chromatography with 40%-50% ethyl acetate:hexanes. The appropriate fractions were combined and concentrated to provide compound 295 as a white solid characterized by MS and 1H-NMR (139 mg, LRMS (ESI) [M+H+]+=286.1).

Provenance & Evidence