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

[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.

[6] Due to the weak N-O bond, the isoxazole ring tends to collapse under UV irradiation, rearranging to oxazole through azirine intermediate.

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 of drugs,[9] including the COX-2 inhibitor valdecoxib (Bextra) and a neurotransmitter agonist AMPA.