反应详情

Alternatively, chloroacetylchloride rather than ethyl chloroacetimidate can by used: To a solution of 3-amino-4-n-propylaminobenzonitrile (5.15 g, 29.4 mmol) and triethylamine (4.51 mL) in ethyl acetate (52 mL) at room temperature, chloroacetyl chloride (2.57 mL) is added slowly. After stirring the reaction mixture for 30 minutes at room temperature, acetic acid (5 mL) is added and the reaction mixture heated to reflux. After heating for 20 h, the reaction mixture is cooled to room temperature and diluted with water (50 mL). The organic solution is washed twice with 1.0 M sodium hydroxide (2×50 mL), then washed with an aqueous solution of 0.25 M KH2PO4 (50 mL), followed by brine (50 mL). The organic layer is dried (sodium sulfate), concentrated in vacuo, and the solid recrystallized by heating in ethyl acetate (20 mL), adding hexane (40 mL) and cooling to room temperature with stirring to afford 1-n-Propyl-2-chloromethyl-5-cyanobenzimidazole as brown crystals. 1H NMR (CDCl3): δ 8.08 (d, J=0.8 Hz, 1H), 7.57 (dd, J=1.65, 8.52 Hz, 1H), 7.45 (d, J=8.24 Hz, 1H), 7.26 (s, 1H), 4.84 (s, 2H) 4.24 (t, J=7.6 Hz, 2H), 1.94 (pentet, J=7.4. 7.6 Hz, 2H) 1.03 (t, J=7.4 Hz, 3H).

1. temperaturethe reaction mixture heated to reflux
2. temperatureAfter heating for 20 h
3. temperaturethe reaction mixture is cooled to room temperature
4. washThe organic solution is washed twice with 1.0 M sodium hydroxide (2×50 mL)
5. washwashed with an aqueous solution of 0.25 M KH2PO4 (50 mL)
6. dry with materialThe organic layer is dried (sodium sulfate)
7. concentrationconcentrated in vacuo
8. customthe solid recrystallized
9. temperatureby heating in ethyl acetate (20 mL)
10. additionadding hexane (40 mL)
11. temperaturecooling to room temperature
12. stirringwith stirring