Cesium carbonate → 3-((3-Bromo-2-methylphenylamino)methyl)benzo[b]thiophene-2-carboxylic Acid

Participants

Reaction Conditions

Reaction Steps

A 250-mL single-neck round-bottomed flask equipped with a magnetic stirrer and reflux condenser was purged with nitrogen and charged with 103a (2.26 g, 7.92 mmol), 3-bromo-2-methylaniline (1.77 g, 9.51 mmol) and acetonitrile (50 mL). Cesium carbonate (7.75 g, 23.8 mmol) was added, and the mixture was stirred at 50° C. for 14 h. After this time, the reaction mixture was concentrated under reduced pressure and the resulting residue was dissolved in THF (15 mL), methanol (15 mL) and water (15 mL) and treated with lithium hydroxide monohydrate (1.30 g, 31.0 mmol). After stirring at room temperature for 14 h, the solvent was removed under reduced pressure and the resulting residue was acidified with 2 M hydrochloric acid to pH 5. The resulting mixture was extracted with ethyl acetate (3×30 mL), and the organic extracts were combined and dried over sodium sulfate, filtered and concentrated under reduced pressure. The resulting residue was purified by flash chromatography to afford 103b in 59% yield (1.70 g) as a white solid: mp 120-121° C.; 1H NMR (500 MHz, DMSO-d6) d 8.30 (d, 1H, J=12.5 Hz), 7.98 (d, 1H, J=12.5 Hz), 7.46 (m, 2H), 6.77 (m, 3H), 4.97 (s, 2H), 2.15 (s, 3H); MS (ESI+) m/z 378.9 (M+H).

Provenance & Evidence