反应详情

In a solution of 259 g. (1.1 mol.) of 1-ethyl-4-hydroxy-1H-pyrazolo[3,4-b]pyridine-5-carboxylic acid ethyl ester in 1700 ml. of dimethylformamide, 400 g. of well powdered potassium carbonate and 300 g. of ethyl iodide are introduced. The reaction mixture is stirred for 7 hours at 65° and filtered under suction, while hot, from excess potassium carbonate. Upon standing overnight, 165 g. of 4-ethoxy-1-ethyl-1H-pyrazolo[3,4-b]pyridine-5-carboxylic acid ethyl ester crystallize out of the solution, m.p. 112°-115°. After evaporation of the mother liquor, an additional 80 g. are obtained. The total yield amounts to 85% of theory. The compound is recrystallized from benzene (90°-100°), m.p. 113°-115°.

1. filtrationfiltered under suction
2. waitUpon standing overnight
3. customof 4-ethoxy-1-ethyl-1H-pyrazolo[3,4-b]pyridine-5-carboxylic acid ethyl ester crystallize out of the solution, m.p. 112°-115°
4. customAfter evaporation of the mother liquor
5. customare obtained
6. customThe total yield
7. customThe compound is recrystallized from benzene (90°-100°), m.p. 113°-115°