Ethyl 5-oxo-4,5-dihydropyrazolo[1,5-a]pyrimidine-3-carboxylate

Ethyl 5-oxo-4,5-dihydropyrazolo[1,5-a]pyrimidine-3-carboxylate Property

Boiling point:

339.6±42.0 °C(Predicted)

Density 

1.47±0.1 g/cm3(Predicted)

storage temp. 

2-8°C

pka

10.81±0.20(Predicted)

Appearance

White to off-white Solid

InChI

InChI=1S/C9H9N3O3/c1-2-15-9(14)6-5-10-12-4-3-7(13)11-8(6)12/h3-5H,2H2,1H3,(H,11,13)

InChIKey

PCKVUOAPCLMZJI-UHFFFAOYSA-N

SMILES

C12=C(C(OCC)=O)C=NN1C=CC(=O)N2

Safety

HazardClass 

IRRITANT

Hazard and Precautionary Statements (GHS)

Symbol(GHS)

Signal word

Warning

Hazard statements

H315Causes skin irritation

H319Causes serious eye irritation

H335May cause respiratory irritation

Precautionary statements

P261Avoid breathing dust/fume/gas/mist/vapours/spray.

P264Wash hands thoroughly after handling.

P264Wash skin thouroughly after handling.

P271Use only outdoors or in a well-ventilated area.

P280Wear protective gloves/protective clothing/eye protection/face protection.

P302+P352IF ON SKIN: wash with plenty of soap and water.

P304+P340IF INHALED: Remove victim to fresh air and Keep at rest in a position comfortable for breathing.

P305+P351+P338IF IN EYES: Rinse cautiously with water for several minutes. Remove contact lenses, if present and easy to do. Continuerinsing.

P312Call a POISON CENTER or doctor/physician if you feel unwell.

P321Specific treatment (see … on this label).

P332+P313IF SKIN irritation occurs: Get medical advice/attention.

P337+P313IF eye irritation persists: Get medical advice/attention.

P362Take off contaminated clothing and wash before reuse.

P403+P233Store in a well-ventilated place. Keep container tightly closed.

P405Store locked up.

P501Dispose of contents/container to..…

Ethyl 5-oxo-4,5-dihydropyrazolo[1,5-a]pyrimidine-3-carboxylate Chemical Properties,Usage,Production

Uses

Ethyl 5-oxo-4,5-dihydropyrazolo[1,5-a]pyrimidine-3-carboxylate is mainly used in organic synthesis and drug development.

Synthesis

Ethyl 3-amino-1H-pyrazole-4-carboxylate (25.0 g, 161 mmol) was mixed with ethyl (E)-3-ethoxyacrylate (35.8 mL, 242 mmol) in N,N-dimethylformamide (DMF, 537 mL). Cesium carbonate (78.7 g, 242 mmol) was added to the mixture, and the reaction system was then heated to 110 °C for 15 hours. After the reaction was complete, the mixture was cooled to room temperature and the pH was adjusted to 4 with acetic acid (HOAc). The precipitate was collected by filtration and washed with water and ethyl acetate (Chemicalbook EtOAc) to give ethyl 5-oxo-4,5-dihydropyrazolo[1,5-a]pyrimidine-3-carboxylate as a fluffy white solid. Additional product was recovered by aqueous workup. The filtrate was concentrated to remove DMF, diluted with EtOAc (500 mL), and washed with deionized water. The precipitate in the EtOAc layer was filtered and washed with water and EtOAc to obtain additional product. All solid products were combined and dried in vacuo to obtain 5-hydroxypyrazolo[1,5-a]pyrimidine-3-carboxylic acid ethyl ester (33.3 g, yield 100%). 3-Amino-1H-pyrazole-4-carboxylic acid ethyl ester (25.0 g, 161 mmol) and (E)-3-ethoxyacrylate ethyl ester (35.8 mL, 242 mmol) were mixed in N,N-dimethylformamide (DMF, 537 mL). Cesium carbonate (78.7 g, 242 mmol) was added to the mixture, and the reaction system was then heated to 110 ° C for 15 hours. After the reaction was completed, the mixture was cooled to room temperature and the pH was adjusted to 4 with acetic acid (HOAc). The precipitate was collected by filtration and washed with water and ethyl acetate (Chemicalbook EtOAc) to give ethyl 5-oxo-4,5-dihydropyrazolo[1,5-a]pyrimidine-3-carboxylate as a fluffy white solid. Additional product can be recovered by aqueous post-treatment. The filtrate was concentrated to remove DMF, diluted with EtOAc (500 mL), and washed with deionized water. The precipitate in the EtOAc layer was filtered and washed with water and EtOAc to give additional product. All solid products were combined and dried in vacuo to finally obtain ethyl 5-hydroxypyrazolo[1,5-a]pyrimidine-3-carboxylate (33.3 g, 100% yield).

References

[1] Patent: WO2011/6074, 2011, A1. Location in patent: Page/Page column 70