Hydrochloric Acid → 6-Cyclopentylmethyl-1-(2,6-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-(2,6-dimethylphenyl)-1H-pyrazole-4-carboxamide (Example 15A) 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 sodium chloride precipitated thereby is filtered off. The filtrate is concentrated in vacuo, and the remaining residue is purified by preparative HPLC (YMC Gel ODS-AQ S 5/15 μm; eluent A: water, eluent B: acetonitrile; gradient: 0 min 30% B, 5 min 30% B, 50 min 95% B). 74 mg (53% of theory) of the product are obtained as a colourless solid.

Provenance & Evidence