Hydrochloric Acid → 6-Cyclopentylmethyl-1-(2,3-dimethylphenyl)-1,5-dihydropyrazolo[3,4-d]pyrimidin-4-one

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Reaction Steps

0.1 g (0.43 mmol) of 5-amino-1-(2,3-dimethylphenyl)-1H-pyrazole-4-carboxamide (Example 16A) is dissolved under argon in 6 ml of absolute ethanol and 0.24 g (1.7 mmol) of methyl cyclopentylacetate and 0.17 g (4.34 mmol) of 60% sodium hydride (suspension in mineral oil) are added. The reaction mixture is heated to reflux overnight. Cooling to room temperature is followed by acidification with concentrated hydrochloric acid. The mixture of sodium chloride and the product precipitated thereby is filtered off and washed several times with water and diethyl ether. Drying under high vacuum results in 69 mg (49% of theory) of the product as colourless solid.

Provenance & Evidence