Sodium Hydroxide → 5-(2-Ethoxyphenyl)-1,6-dihydro-1,3-dimethyl-7H-pyrazolo[4,3-d]pyrimidin-7-one

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Reaction Conditions

Reaction Steps

4-(2-Ethoxybenzamido)-1,3-dimethylpyrazole-5-carboxamide (1.6 g, 5.29 mmol) was added to polyphosphoric acid (50 g) and the mixture heated to 140° C. for 6 hours. The solution was cooled, poured into ice-water (100 ml), and then the mixture was basified with 10% aqueous sodium hydroxide solution and extracted with dichloromethane (3×100 ml). The organic extracts were combined, dried (MgSO4) and evaporated under vacuum. The residue was chromatographed on silica gel eluting with a 97:3 mixture of dichloromethane and methanol. Crystallisation of the crude product from aqueous ethanol gave the title compound as a colourless solid, m.p. 201°-204° C. Found: C,63.43; H,5.57; N,19.35. C15H16N4O2 requires C,63.36; H,5.67; N,19.71%.

Provenance & Evidence