Hydrochloric Acid → 7-(3-Thienyl)pyrazolo[1,5-a]pyrimidine-3-carboxylic acid

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Reaction Steps

A mixture of 0.05 mole of ethyl 7-(3-thienyl)pyrazolo[1,5-a]pyrimidine-3-carboxylate and 0.20 mole of potassium hydroxide in 50 ml. of ethanol-water is heated at reflux temperature for 4 hours. The mixture is acidified with concentrated hydrochloric acid and concentrated to give 7-(3-thienyl)pyrazolo[1,5-a]pyrimidine-3-carboxylic acid. The preceding compound in tetrahydrofuran is added dropwise to a solution of 0.10 mole of diborane in tetrahydrofuran chilled in an ice bath. After stirring for 2 hours the bath is removed and the mixture allowed to stand 6 hours at room temperature. The mixture is poured into ice to give the product of the example.

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