Cesium carbonate → allyl 2-amino-5-oxo-4H-pyrazolo[1,5-a]pyrimidine-3-carboxylate

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Reaction Steps

To a suspension of allyl 3,5-diamino-1H-pyrazole-4-carboxylate 3 (1.0 g, 5.4 mmol) and Cs2CO3 (2.5 g, 7.6 mmol) in EtOH (10 mL) was added methyl prop-2-ynoate (553.0 mg, 586.0 μl, 6.5 mmol), dropwise over 15 minutes and the reaction mixture was stirred overnight at room temperature. The deep orange mixture was filtered. The filtrate was cooled on an ice-bath and ether (100 mL) was slowly added with stirring. The mixture was stirred at 0° C. for 20 minutes by which time a yellow solid had precipitated out of solution. The solid was filtered, further triturated in ether (20 mL) and filtered. The yellow solid was dried to afford allyl 2-amino-5-oxo-4,5-dihydropyrazolo[1,5-a]pyrimidine-3-carboxylate (700 mg, 54% yield).

Provenance & Evidence