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| Names | |||
|---|---|---|---|
| Preferred IUPAC name 1,2-Oxazole[1] | |||
| Other names isoxazole | |||
| Identifiers | |||
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3D model (JSmol) | |||
| ChEBI | |||
| ChEMBL | |||
| ChemSpider |
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| ECHA InfoCard | 100.005.472 | ||
| UNII | |||
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| Properties | |||
| 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)[2] | ||
Except where otherwise noted, data are given for materials in theirstandard state (at 25 °C [77 °F], 100 kPa). | |||
Isoxazole is an electron-richazole with anoxygenatom next to thenitrogen. It is also the class of compounds containing this ring.Isoxazolyl is theunivalentfunctional group derived from isoxazole.
Isoxazole rings are found in some natural products, such asibotenic acid andmuscimol.
Isoxazole can be synthesised via a variety of methods.[3][4]Examples include via a1,3-dipolar cycloaddition ofnitrile oxides withalkynes; or the reaction ofhydroxylamine with1,3-diketones or derivatives ofpropiolic acid.[5]
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]
Isoxazoles also form the basis for a number ofdrugs,[9] including the COX-2 inhibitorvaldecoxib (Bextra) and aneurotransmitter agonistAMPA. A derivative,furoxan, is anitric oxide donor. An isoxazolyl group is found in manybeta-lactamase-resistant antibiotics, such ascloxacillin,dicloxacillin andflucloxacillin. Leflunomide is an isoxazole-derivative drug. Examples ofAAS containing the isoxazole ring includedanazol andandroisoxazole. A number ofpesticides are isoxazoles.[10]Gaboxadol is aconformationally constrained isoxazole derivative ofmuscimol.
