反应详情

To a stirred solution of 4-methyl-benzimidazole-1-carboxylic acid tert-butyl ester (800 mg, 3.4 mmol) in CCl4 (7 mL) was added N-bromosuccinimide (730 mg, 4.1 mmol) and 2,2′-azobis(2-methylpropionitrile) (84 mg, 0.51 mmol). The resultant mixture was heated at reflux for 18 h after which it was filtered and concentrated to a yellow/orange syrup and crystals (1.4 g). Purification by column chromatography on silica gel (200:15—Hexanes:EtOAc) gave the desired title compound as a yellow syrup (635 mg, 60%). 1H NMR (300 MHz, CDCl3) δ8.48 (s, 1H), 7.95 (dd, 1H, J=7.8, 1.5 Hz), 7.42-7.34 (m, 2H), 4.96 (s, 2H), 1.71 (s, 9H).

1. temperatureat reflux for 18 h after which it
2. filtrationwas filtered
3. concentrationconcentrated to a yellow/orange syrup and crystals (1.4 g)
4. customPurification by column chromatography on silica gel (200:15—Hexanes:EtOAc)