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.
Occurrence
Isoxazole rings are found in some natural products, such as
ibotenic acid and
muscimol.
Synthesis
Isoxazole can be synthesised via a variety of methods.
Examples include via a 1,3-dipolar cycloaddition of
with
; or the reaction of
hydroxylamine with 1,3-diketones or derivatives of
propiolic acid.
Photochemistry
The photolysis of isoxazole was first reported in 1966.
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.
Pharmaceuticals and herbicides
Isoxazoles also form the basis for a number of
Drug,
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
Anabolic steroid containing the isoxazole ring include
danazol and
androisoxazole. A number of
Pesticide are isoxazoles.
is a conformationally constrained isoxazole derivative of
muscimol.
See also
External links
