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

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).

1. filtrationThe deep orange mixture was filtered
2. temperatureThe filtrate was cooled on an ice-bath
3. additionether (100 mL) was slowly added
4. stirringwith stirring
5. stirringThe mixture was stirred at 0° C. for 20 minutes by which time a yellow solid
6. customhad precipitated out of solution
7. filtrationThe solid was filtered
8. customfurther triturated in ether (20 mL)
9. filtrationfiltered
10. customThe yellow solid was dried

ORD record

ord-7573c2ed33064e1486579d7c41a36c93

Source dataset

uspto-grants-2015_02

DOI

10.6084/m9.figshare.5104873.v1

Patent number

US08957078B2