Open Access Articles- Top Results for Pyrazole
Chemical Sciences JournalSynthesis and Pharmacological Evaluation of Some Pyrazoles, Thiazolopyrimidine, Triazolopyrimidine, Pyridone and 2-Iminochromene Containing Naproxenoy
Organic Chemistry: Current ResearchSynthesis, Biological Evaluation of Some 2,3-dihydropyrazoles and Thiazoles as Anti-inflammatory and Antibacterial Agents
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Pyrazole is the organic compound with the formula C3H3N2H. It is a heterocycle characterized by a 5-membered ring of three carbon atoms and two adjacent nitrogen atoms. Pyrazoles are also the class of compounds that have the ring C3N2 with adjacent nitrogen atoms. A notable drug containing a pyrazole ring is celecoxib (Celebrex).
Preparation and reactions
- CH3C(O)CH2C(O)CH3 + N2H4 → (CH3)2C3HN2H + 2 H2O
The term pyrazole was given to this class of compounds by German Chemist Ludwig Knorr in 1883. In a classical method developed by German chemist Hans von Pechmann in 1898, pyrazole was synthesized from acetylene and diazomethane.
Conversion to scorpionates
Pyrazoles react with potassium borohydride to form a class of ligands known as scorpionate. Pyrazole itself reacts with potassium borohydride at high temperatures (~200 °C) to form a tridentate ligand known as Tp ligand:
- KBH4 + 3 C3H3N2H → KBH(C3H3N2)3 + 3 H2
Occurrence and uses
In medicine, derivatives of pyrazoles are used for their analgesic, anti-inflammatory, antipyretic, antiarrhythmic, tranquilizing, muscle relaxing, psychoanaleptic, anticonvulsant, monoamineoxidase inhibiting, antidiabetic and antibacterial activities.
- Eicher, T.; Hauptmann, S. (2003). The Chemistry of Heterocycles: Structure, Reactions, Syntheses, and Applications (2nd ed.). Wiley-VCH. ISBN 3-527-30720-6.
- A. Schmidt, A. Dreger (2011). "Recent Advances in the Chemistry of Pyrazoles. Properties, Biological Activities, and Syntheses". Curr. Org. Chem 15 (9): 1423–1463. doi:10.2174/138527211795378263.
- William S. Johnson and Robert J. Highet (1963). "3,5-Dimethylpyrazole". Org. Synth.; Coll. Vol. 4, p. 351
- H. v. Pechmann (1898). "Pyrazol aus Acetylen und Diazomethan". Berichte der deutschen chemischen Gesellschaft 31 (3): 2950–51. doi:10.1002/cber.18980310363.
- Fowden; Noe, Ridd and White (1959). Proc. Chem. SOC.: 131. Missing or empty
- Noe, F F; L Fowden; Richmond, P. T. (1959). "alpha-Amino-beta-(pyrazolyl-N) propionic acid: a new amino-acid from Citrullus vulgaris (water melon)". Nature 184 (4688): 69–70. Bibcode:1959Natur.184...69B. ISSN 0028-0836. doi:10.1038/184069a0.
A. Schmidt, A. Dreger (2011). "Recent Advances in the Chemistry of Pyrazoles. Part 2. Reactions and N-Heterocyclic Carbenes of Pyrazole". Curr. Org. Chem. 15 (16): 2897 – 2970. doi:10.2174/138527211796378497.