Methanol → Methyl 3-amino-2-fluorobenzoate

Participants

Reaction Steps

To a stirred solution of 3-amino-2-fluoro-benzoic acid (25 g, 161 mmol) in methanol (300 mL) was added thionyl chloride (30 mL, 403 mmol) dropewise at 0° C. Then the mixture solution was refluxed for 12 hours before cooling to room temperature. Then the reaction mixture was concentrated in vacuo and the residue was dissolved in ethyl acetate (500 mL), washed with saturated aqueous sodium bicarbonate solution (3×100 mL), dried over anhydrous sodium sulfate and concentrated in vacuo to afford 3-amino-2-fluoro-benzoic acid methyl ester (27.5 g, quant.) as a pale-white solid: LC/MS m/e calcd for C8H8FNO2 (M+H)+: 170.16, observed: 169.9. A mixture solution of 3-amino-2-fluoro-benzoic acid methyl ester (26 g, 153.8 mmol), 3-bromo-benzaldehyde (28.5 g, 153.8 mmol) and p-toluenesulfonic acid (590 mg, 3.2 mmol) in toluene (200 mL) was heated to reflux for 12 hours. Then the reaction mixture was cooled to room temperature. The solvent was removed in vacuo and the residue was washed with ether to afford 3-[(3-bromo-benzylidene)-amino]-2-fluoro-benzoic acid methyl ester (51.7 g, quant.) as a pale-white solid: MS calcd. for C15H11BrFlNO2 337.16, obsd. (ESI+) [(M+H)+] 336.0 & 338.0.

Provenance & Evidence