反应详情

6-(4-Chloro-2-methyl-phenylamino)-7-fluoro-3H-benzoimidazole-5-carboxylic acid hydrazide 20b (0.048 g, 0.144 mmol) is suspended in 3 mL absolute EtOH and HC(OEt)3 (0.60 mL, 3.54 mmol) is added followed by catalytic pTsOH.H2O. The reaction mixture is heated to reflux under N2. After 2 hours, the reaction mixture is cooled to room temperature and concentrated under reduced pressure. Purification by flash column chromatography (97:3 ethyl acetate:MeOH) provides 36 mg (73%) desired product as a light yellow solid. LC/MS ESI (+) m/z 344, 346 (M+ Cl pattern) detected; 1H NMR (400 MHz, DMSO-d6) δ13.10 (bs, 1H), 9.39 (s, 1H), 8.49 (s, 1H), 8.10 (bs, 1H), 7.78 (bs, 1H), 7.20 (d, 1H), 7.00 (dd, 1H), 6.41 (bs, 1H), 2.18 (s, 3H).

1. temperatureThe reaction mixture is heated
2. temperatureto reflux under N2
3. concentrationconcentrated under reduced pressure
4. customPurification by flash column chromatography (97:3 ethyl acetate:MeOH)