Isoxazole is an electron-rich
azole with an
oxygenatom next to the
nitrogen. It is also the class of compounds containing this ring. Isoxazolyl is the
univalentfunctional group derived from isoxazole.
Occurrence
Isoxazole rings are found in some natural products, such as
ibotenic acid and
muscimol.
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]
^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.
^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.