Pyrazolone

From Wikipedia, the free encyclopedia

Pyrazolone is 5-membered heterocycle containing two adjacent nitrogen atoms. It can be viewed as a derivative of pyrazole possessing an additional carbonyl (C=O) group. Compounds containing this functional group are useful commercially in analgesics and dyes.[1]

Structure and synthesis[]

Pyrazolone can exist in two isomers: 3-pyrazolone and 4-pyrazolone.

Chemical structures of 3-pyrazolone (left) and 4-pyrazolone (right)

These isomers can interconvert via lactam–lactim and imine–enamine tautomerism; these conversion often display photochromism. For pyrazolone derivatives, the 3-pyrazolone isomer can be stabilized with N-alkyl or N-aryl substituents.

Lactam-Lactim-Tautomerie Pyrazolone.svg

The first synthesis of pyrazolones was reported in 1883 by Ludwig Knorr, via a condensation reaction between ethyl acetoacetate and phenylhydrazine.[2]

KnorrPrep.png

Many pyrazolones are produced by functionalization of preformed pyrazolones.

Applications[]

Pharmaceuticals[]

Antipyrine (phenazone), the earliest pyrazolone based drug

Pyrazolones are amongst the oldest synthetic pharmaceuticals, starting with the introduction of antipyrine (phenazone) in 1880s.[3][4] The compounds generally act as analgesics and include dipyrone (Metamizole), aminopyrine, ampyrone, famprofazone, morazone, nifenazone, piperylon and propyphenazone, aminophenazone. Of these dipyrone is perhaps the most widely used.[3][5] Edaravone is useful for prevention and/or therapy of arterial wall injury.[6] Eltrombopag is used to address low blood platelet count.

Dyes[]

Pyrazolone groups are present in several important dyes. They are commonly used in combination with azo groups to give a sub-family of azo dyes; sometimes referred to as azopyrazolones (tartrazine, orange B, mordant red 19, yellow 2G). , Acid Yellow 23 (tartrazine), Pigment Yellow 13, and are produced on the multi-ton scale annually.[1]

Ligands[]

Pyrazolones have been studied as ligands.[7]

References[]

  1. ^ Jump up to: a b Kornis, Gabe I. (2000). "Pyrazoles, Pyrazolines, and Pyrazolones". Kirk-Othmer Encyclopedia of Chemical Technology. doi:10.1002/0471238961.1625180111151814.a01. ISBN 0471238961.
  2. ^ Knorr, Ludwig (July 1883). "Einwirkung von Acetessigester auf Phenylhydrazin". Berichte der Deutschen Chemischen Gesellschaft (in German). 16 (2): 2597–2599. doi:10.1002/cber.188301602194.
  3. ^ Jump up to: a b Brogden, Rex N. (1986). "Pyrazolone Derivatives". Drugs. 32 (Supplement 4): 60–70. doi:10.2165/00003495-198600324-00006. PMID 3552586. S2CID 2761563.
  4. ^ Brune, Kay (December 1997). "The early history of non-opioid analgesics". Acute Pain. 1 (1): 33–40. doi:10.1016/S1366-0071(97)80033-2.
  5. ^ Zhao, Zefeng; Dai, Xufen; Li, Chenyang; Wang, Xiao; Tian, Jiale; Feng, Ying; Xie, Jing; Ma, Cong; Nie, Zhuang; Fan, Peinan; Qian, Mingcheng; He, Xirui; Wu, Shaoping; Zhang, Yongmin; Zheng, Xiaohui (2020). "Pyrazolone structural motif in medicinal chemistry: Retrospect and prospect". European Journal of Medicinal Chemistry. 186: 111893. doi:10.1016/j.ejmech.2019.111893. PMC 7115706. PMID 31761383.
  6. ^ Bailly, Christian; Hecquet, Paul-Emile; Kouach, Mostafa; Thuru, Xavier; Goossens, Jean-François (2020). "Chemical reactivity and uses of 1-phenyl-3-methyl-5-pyrazolone (PMP), also known as edaravone". Bioorganic & Medicinal Chemistry. 28 (10): 115463. doi:10.1016/j.bmc.2020.115463. PMID 32241621.
  7. ^ CASAS, J; GARCIATASENDE, M; SANCHEZ, A; SORDO, J; TOUCEDA, A (June 2007). "Coordination modes of 5-pyrazolones: A solid-state overview". Coordination Chemistry Reviews. 251 (11–12): 1561–1589. doi:10.1016/j.ccr.2007.02.010.

External links[]

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