Acetic Acid → 3-(Propan-2-yl)-2H-pyrazolo[4,3-d]pyrimidine-5,7(4H,6H)-dione

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Reaction Conditions

Reaction Steps

Mixture of 4-amino-5-isopropylpyrazole-3-carboxamide (770 mg, 4.58 mmol) and urea (1.4 g, 4.58 mmol) was fused at 180° C. for 30 min. After cooling, the solid was dissolved in 2.3 mL of 2 M sodium hydroxide. The boiling solution was acidified with glacial acetic acid and the warm solution was filtered. This solution was cooled to 5° C. and the product started to precipitate after a few minutes. The crude product (1.3 g) was recrystallized twice from a hot water. Yield 78.5%; mp=295-298° C. 1H NMR (300 MHz, DMSO): 1.21 d (6H, J=6.6 Hz), 3.17 sept (1H, J=6.6 Hz). MS (EI): 194(94; C8H10N4O2); 179(100; C7H7N4O2); 162(51; C7H4N3O2); 136(15); 123(7); 95(8); 81(13); 54(26); 43(23).

Provenance & Evidence