Isoxazole

Isoxazole
Names
	Preferred IUPAC name 1,2-Oxazole
	Other names isoxazole
Identifiers
CAS Number	288-14-2 ;
3D model (JSmol)	Interactive image;
ChEBI	CHEBI:35595 ;
ChEMBL	ChEMBL13257 ;
ChemSpider	8897 ;
ECHA InfoCard	100.005.472
PubChem CID	9254;
UNII	00SRW0M6PW ;
CompTox Dashboard (EPA)	DTXSID7059775 ;
	InChI InChI=1S/C3H3NO/c1-2-4-5-3-1/h1-3H Key: CTAPFRYPJLPFDF-UHFFFAOYSA-N ; InChI=1/C3H3NO/c1-2-4-5-3-1/h1-3H Key: CTAPFRYPJLPFDF-UHFFFAOYAS;
	SMILES n1occc1;
Properties
Chemical formula	C3H3NO
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)
	Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa). verify (what is ?) Infobox references

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

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

Synthesis

Isoxazole can be synthesised via a variety of methods.^[3]^[4] Examples include via a 1,3-dipolar cycloaddition of nitrile oxides with alkynes; or the reaction of hydroxylamine with 1,3-diketones or derivatives of propiolic acid.^[5]

Photochemistry

The photolysis of isoxazole was first reported in 1966.^[6] Due to the weak N-O bond, the isoxazole ring tends to collapse under UV irradiation, rearranging to oxazole through azirine intermediate. Meanwhile, the azirine intermediate can react with nucleophiles, especially carboxylic acids. Given the photoreactions, isoxazole group is developed as a native photo-cross-linker for photoaffinity labeling and chemoproteomic studies.^[7] ^[8]

Pharmaceuticals and herbicides

Isoxazoles also form the basis for a number of drugs,^[9] 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.^[10]

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

Oxazole, an analog with the nitrogen atom in position 3
Pyrrole, an analog without the oxygen atom
Furan, an analog without the nitrogen atom
Simple aromatic rings

[1]
International Union of Pure and Applied Chemistry (2014). Nomenclature of Organic Chemistry: IUPAC Recommendations and Preferred Names 2013. The Royal Society of Chemistry. p. 140. doi:10.1039/9781849733069. ISBN 978-0-85404-182-4.
[2]
Zoltewicz, J. A. & Deady, L. W. Quaternization of heteroaromatic compounds. Quantitative aspects. Adv. Heterocycl. Chem. 22, 71-121 (1978)
[3]
Dasa S, Chanda K (2021). "An overview of metal-free synthetic routes to isoxazoles: the privileged scaffold". RSC Adv (11): 32680–32705. doi:10.1039/D1RA04624A. PMC 9042182.
[4]
Morita, Taiki; Yugandar, Somaraju; Fuse, Shinichiro; Nakamura, Hiroyuki (March 2018). "Recent progresses in the synthesis of functionalized isoxazoles". Tetrahedron Letters. 59 (13): 1159–1171. doi:10.1016/j.tetlet.2018.02.020.
[5]
Hossain M, Khan M, Kim S, Le H (2022). "Synthesis of 3,4,5-trisubstituted isoxazoles in water via a [3 + 2]-cycloaddition of nitrile oxides and 1,3-diketones, β-ketoesters, or β-ketoamides". Beilstein J. Org. Chem. (18): 446–458. doi:10.3762/bjoc.18.47. PMC 9039522. PMID 35529890.
[6]
Edwin F. Ullman (1966). "Photochemical Transposition of Ring Atoms in Five-Membered Heterocycles. The Photorearrangement of 3,5-Diphenylisoxazole". J. Am. Chem. Soc. 88 (8): 1844–1845. doi:10.1021/ja00960a066.
[7]
Cheng, K.; Qi, J.; Ren, X.; Zhang, J.; Li, H.; Xiao, H.; Wang, R.; Liu, Z.; Meng, L.; Ma, N.; Sun, H. (2022). "Developing Isoxazole as a Native Photo-Cross-Linker for Photoaffinity Labeling and Chemoproteomics". Angew. Chem. Int. Ed. 61 (47): e202209947. doi:10.1002/anie.202209947.
[8]
Lougee, M.; Pagar, V.; Kim, H.; Pancoe, S.; Chia, W.; Mach, R.; Garcia, B.; Petersson, E. (2022). "Harnessing the Intrinsic Photochemistry of Isoxazoles for the Development of Chemoproteomic Crosslinking Methods". Chem. Comm. 58 (65): 9116–9119. doi:10.1039/D2CC02263J. PMC 9922157.
[9]
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.
[10]
Clemens Lamberth (2018). "Oxazole and Isoxazole Chemistry in Crop Protection". Journal of Heterocyclic Chemistry. 55 (9): 2035–2045. doi:10.1002/jhet.3252.

Synthesis of isoxazoles (overview of recent methods)

[1] [1]
International Union of Pure and Applied Chemistry (2014). Nomenclature of Organic Chemistry: IUPAC Recommendations and Preferred Names 2013. The Royal Society of Chemistry. p. 140. doi:10.1039/9781849733069. ISBN 978-0-85404-182-4.

[2] [2]
Zoltewicz, J. A. & Deady, L. W. Quaternization of heteroaromatic compounds. Quantitative aspects. Adv. Heterocycl. Chem. 22, 71-121 (1978)

[3] [3]
Dasa S, Chanda K (2021). "An overview of metal-free synthetic routes to isoxazoles: the privileged scaffold". RSC Adv (11): 32680–32705. doi:10.1039/D1RA04624A. PMC 9042182.

[4] [4]
Morita, Taiki; Yugandar, Somaraju; Fuse, Shinichiro; Nakamura, Hiroyuki (March 2018). "Recent progresses in the synthesis of functionalized isoxazoles". Tetrahedron Letters. 59 (13): 1159–1171. doi:10.1016/j.tetlet.2018.02.020.

[5] [5]
Hossain M, Khan M, Kim S, Le H (2022). "Synthesis of 3,4,5-trisubstituted isoxazoles in water via a [3 + 2]-cycloaddition of nitrile oxides and 1,3-diketones, β-ketoesters, or β-ketoamides". Beilstein J. Org. Chem. (18): 446–458. doi:10.3762/bjoc.18.47. PMC 9039522. PMID 35529890.

[6] [6]
Edwin F. Ullman (1966). "Photochemical Transposition of Ring Atoms in Five-Membered Heterocycles. The Photorearrangement of 3,5-Diphenylisoxazole". J. Am. Chem. Soc. 88 (8): 1844–1845. doi:10.1021/ja00960a066.

[7] [7]
Cheng, K.; Qi, J.; Ren, X.; Zhang, J.; Li, H.; Xiao, H.; Wang, R.; Liu, Z.; Meng, L.; Ma, N.; Sun, H. (2022). "Developing Isoxazole as a Native Photo-Cross-Linker for Photoaffinity Labeling and Chemoproteomics". Angew. Chem. Int. Ed. 61 (47): e202209947. doi:10.1002/anie.202209947.

[8] [8]
Lougee, M.; Pagar, V.; Kim, H.; Pancoe, S.; Chia, W.; Mach, R.; Garcia, B.; Petersson, E. (2022). "Harnessing the Intrinsic Photochemistry of Isoxazoles for the Development of Chemoproteomic Crosslinking Methods". Chem. Comm. 58 (65): 9116–9119. doi:10.1039/D2CC02263J. PMC 9922157.

[9] [9]
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.

[10] [10]
Clemens Lamberth (2018). "Oxazole and Isoxazole Chemistry in Crop Protection". Journal of Heterocyclic Chemistry. 55 (9): 2035–2045. doi:10.1002/jhet.3252.

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Isoxazole

Synthesis

Photochemistry

Pharmaceuticals and herbicides

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Isoxazole

Synthesis

Photochemistry

Pharmaceuticals and herbicides

Wikiwand in your browser!

Occurrence

See also

References

External links