反应详情

20 g (137 mmol) 1H-indazole-5-carbaldehyde [preparation described in US 2005/0227968-A1 (Intermediate 1)], dissolved in 1,4-dioxane (640 ml), were treated with a solution of sodium hydroxide (82 g, 2053 mmol) in water (640 ml). Then, 43.2 g (170 mmol) iodine were added, and the mixture was stirred at room temperature for 1 h. Subsequently, a second batch of 43.2 g (170 mmol) iodine was added, and the mixture was again stirred at room temperature for 1 h. The mixture was concentrated under reduced pressure yielding a solid precipitate. After filtration, the precipitate was washed with water and dried under high vacuum over phosphorous oxide in a desiccator for 12 h affording the title compound (26.6 g, 72% of th.) as a pale yellow solid.

1. stirringthe mixture was again stirred at room temperature for 1 h
2. concentrationThe mixture was concentrated under reduced pressure
3. customyielding a solid precipitate
4. filtrationAfter filtration
5. washthe precipitate was washed with water
6. dry with materialdried under high vacuum over phosphorous oxide in a desiccator for 12 h