反应详情

温度

23 °C

O-iso-Butylhydroxylamine hydrochloride (380 mg, 3.0 mmol, 2.0 equiv) and 4-(dimethylamino)pyridine (740 mg, 6.0 mmol, 4.0 equiv) were sequentially added to a stirred suspension of 4-amino-3-chloro-6-(4-chloro-2-fluoro-3-methoxyphenyl)picolinic acid (prepared as in Balko et al., U.S. Pat. No. 7,314,849 B2; 500 mg, 1.5 mmol, 1.0 equiv) and 1-ethyl-3-(3-dimethylaminopropyl)-carbodiimide hydrochloride (1.2 g, 6.0 mmol, 4.0 equiv) in 1,2-dichloroethane (5.0 mL) at 23° C. The resulting tan suspension was stirred at 23° C. for 18 h. The reaction mixture was quenched with glacial acetic acid (430 μL, 7.5 mmol, 5.0 equiv) and concentrated by a nitrogen stream. The residue was directly subjected to silica gel column chromatography (50% EtOAc in hexane) to afford a white powder (370 mg, 61%): mp 145-148° C.; 1H NMR (300 MHz, CDCl3) δ 9.87 (br s, 1H), 7.53 (t, J=8 Hz, 1H), 7.26 (m, 1H), 7.18 (d, J=2 Hz, 1H), 4.95 (br s, 2H), 3.99 (d, J=1 Hz, 3H), 3.83 (d, J=7 Hz, 2H), 2.07 (m, 1H), 1.01 (d, J=6 Hz, 6H); IR (neat film) 3221 (m), 2941 (w), 2878 (w), 1653 (s) cm−1; ESIMS m/z 402.2 ([M+H]+).

1. customprepared as in Balko et al., U.S
2. customat 23° C
3. concentrationconcentrated by a nitrogen stream