反应详情

In ethanol (200 ml), 1,2,3,4-tetrahydrobenzo[4,5]imidazo[1,2-a]pyrazine-8-carboxylic acid (2.94 g, 13.53 mmol) prepared in the Step 38-1-4 was suspended. Concentrated sulfuric acid (10 ml) was added thereto, and the mixture was heated under reflux for 72 hours. After being allowed to cool, the mixture was concentrated under a reduced pressure. The concentrate was neutralized with a saturated sodium bicarbonate solution and 25% ammonia water and then subjected to extraction with chloroform. The extract was dried over anhydrous magnesium sulfate and then concentrated under a reduced pressure. The concentrate was purified by silica gel column chromatography (chloroform:methanol=10:1) to give the title compound (2.78 g, 84%) as a light-yellow powder.

1. temperaturethe mixture was heated
2. temperatureunder reflux for 72 hours
3. temperatureto cool
4. concentrationthe mixture was concentrated under a reduced pressure
5. extractionsubjected to extraction with chloroform
6. dry with materialThe extract was dried over anhydrous magnesium sulfate
7. concentrationconcentrated under a reduced pressure
8. customThe concentrate was purified by silica gel column chromatography (chloroform:methanol=10:1)