Iodoethane → Ethyl 4-ethoxy-1-ethyl-1H-pyrazolo[3,4-b]pyridine-5-carboxylate

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Reaction Steps

In a solution of 259 g. 1-ethyl-4-hydroxy-1H-pyrazolo[3,4-b]pyridine-5-carboxylic acid ethyl ester (1.1 mol.) in 1700 ml. dimethylformamide, 400 g. of well pulverized 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, to remove excess potassium carbonate. Upon standing over night, 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 ligroin (90°-100°), m.p. 113°-115°.

Provenance & Evidence