Hydrogen Bromide → 2-fluoro-N-(2-oxo-1H-pyridin-4-yl)-4-(trifluoromethyl)benzamide

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Reaction Conditions

Reaction Steps

To 2-fluoro-N-(2-methoxy-4-pyridyl)-4-(trifluoromethyl)benzamide (1.00 g, 3.18 mmol) in acetic acid (6.0 mL) was added HBr (33% in acetic acid) (3.9 mL of 33% w/v, 15.91 mmol) and the mixture stirred at 100° C. for 6 hours. Additional HBr (2 mL, 33% in acetic acid) was added and the mixture was stirred at room temperature overnight. The mixture was then heated at 100° C. for 2 hours before it was cooled to room temperature. The mixture was partitioned between ethyl acetate and water. The layers were separated and the aqueous layer was extracted with ethyl acetate (3×). The combined organics were washed with water and brine (2×), dried over sodium sulfate, filtered and concentrated under reduced pressure. The solid was slurried in methyl-tert-butyl ether and filtered to give 2-fluoro-N-(2-oxo-1H-pyridin-4-yl)-4-(trifluoromethyl)benzamide (19) (731 mg, 76%). ESI-MS m/z calc. 301.05, found 301.3 (M+1)+; Retention time: 1.35 minutes (3 minute run). 1H NMR (400 MHz, DMSO-d6) δ 11.33 (s, 1H), 10.70 (s, 1H), 7.96-7.85 (m, 2H), 7.75 (d, J=8.2 Hz, 1H), 7.35 (d, J=7.2 Hz, 1H), 6.81 (d, J=1.9 Hz, 1H), 6.41 (dd, J=7.2, 2.1 Hz, 1H) ppm.

Provenance & Evidence