反应详情

Ethyl 2-aminobenzothiazole-6-carboxylate (7.78 g, 35.0 mmol) prepared in the Step 36-1-1 was dissolved in tetrahydrofuran (100 ml). Amyl nitrite (8.2 g, 70.0 mmol) was added thereto, and the mixture was heated under reflux. After 1.5 hours, amyl nitrite (3.5 g, 30.0 mmol) was added thereto, and the resulting mixture was heated under reflux. After another 0.5 hours, amyl nitrite (2.6 g, 22.3 mmol) was added thereto, and the resulting mixture was heated under reflux. After being heated under reflux for another 3 hours, the resulting mixture was concentrated under a reduced pressure. The concentrate was purified by silica gel column chromatography (chloroform:methanol=100:1-20:1, and then n-hexane:ethyl acetate=3:1) to give the title compound (5.1 g, 70%) as a light-brown powder.

1. temperaturethe mixture was heated
2. temperatureunder reflux
3. temperaturethe resulting mixture was heated
4. temperatureunder reflux
5. waitAfter another 0.5 hours
6. temperaturethe resulting mixture was heated
7. temperatureunder reflux
8. temperatureAfter being heated
9. temperatureunder reflux for another 3 hours
10. concentrationthe resulting mixture was concentrated under a reduced pressure
11. customThe concentrate was purified by silica gel column chromatography (chloroform