Lithium Hydroxide → 7-Hydroxy-5-phenylpyrazolo[1,5-c]pyrimidine-3-carboxylic acid

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Reaction Conditions

Reaction Steps

Ethyl 7-hydroxy-5-phenylpyrazolo[1,5-a]pyrimidine-3-carboxylate (3.1 g, 11 mmol) was taken into 27 mL methanol and 2 M aqueous lithium hydroxide (27 mL) and heated in an 80° C. oil bath for 4 h. The solution was allowed to cool to room temperature and concentrated in vacuo to remove methanol. The subsequent basic aqueous mixture was washed with ethyl acetate (10% methanol) and then acidified to pH 3 using concentrated hydrochloric acid. A solid formed and was collected via vacuum filtration to yield 2.2 g (79%) of crystalline 7-hydroxy-5-phenylpyrazolo[1,5-c]pyrimidine-3-carboxylic acid. 1H NMR (400 MHz, d6-DMSO): 8.21 (s, 1H), 7.76 (m, 2H), 7.57 (m, 3H), 6.24 (s, 1H).

Provenance & Evidence