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Isoxazole is an azole with an oxygen atom next to the nitrogen. It is also the class of compounds containing this ring. Isoxazolyl is the univalent radical derived from isoxazole.

Full structural formula
Skeletal formula with numbers
Ball-and-stick model
Space-filling model
IUPAC name
Other names
3D model (JSmol)
ECHA InfoCard 100.005.472
Molar mass 69.06202 g/mol
Density 1.075 g/ml
Boiling point 95 °C (203 °F; 368 K)
Acidity (pKa) -3.0 (of conjugate acid) [1]
Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa).
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Infobox references


Isoxazole rings are found in some natural products, such as ibotenic acid and muscimol.

Pharmaceuticals and herbicidesEdit

Isoxazoles also form the basis for a number of drugs,[2] including the COX-2 inhibitor valdecoxib (Bextra) and a neurotransmitter agonist AMPA. A derivative, furoxan, is a nitric oxide donor. An isoxazolyl group is found in many beta-lactamase-resistant antibiotics, such as cloxacillin, dicloxacillin and flucloxacillin. Leflunomide is an isoxazole-derivative drug. Examples of AAS containing the isoxazole ring include danazol and androisoxazole. A number of pesticides are isoxazoles.[3]

Isoxaben is an example of an isoxazole used as a herbicide.

See alsoEdit


  1. ^ Zoltewicz, J. A. & Deady, L. W. Quaternization of heteroaromatic compounds. Quantitative aspects. Adv. Heterocycl. Chem. 22, 71-121 (1978).
  2. ^ Zhu, Jie; Mo, Jun; Lin, Hong-zhi; Chen, Yao; Sun, Hao-peng (2018). "The recent progress of isoxazole in medicinal chemistry". Bioorganic & Medicinal Chemistry. 26 (12): 3065–3075. doi:10.1016/j.bmc.2018.05.013.CS1 maint: uses authors parameter (link)
  3. ^ Clemens Lamberth (2018). "Oxazole and Isoxazole Chemistry in Crop Protection". Journal of Heterocyclic Chemistry. 55 (9): 2035–2045. doi:10.1002/jhet.3252.

External linksEdit