反应详情

360 ml. of aqueous sodium hydroxide (2.5 N) are added to a solution of 47.5 g. of 6-ethoxy-1-ethyl-1H-pyrazolo[3,4-b]-pyrazine-5-carboxylic acid ethyl ester (0.18 mol.) in 360 ml. of ethanol and stirred at room temperature for 15 hours. After removing the alcohol under vacuum, the aqueous solution is acidified with concentrated hydrochloric acid to give 6-ethoxy-1-ethyl-1H-pyrazolo[3,4-b]pyrazine-5-carboxylic acid in a yield of 94%, m.p. 128°-130°. A sample recrystallized from acetonitrile melts at 130°-132°.

1. customAfter removing the alcohol under vacuum