The synthesis of oxazoles by thermolysis or photolysis of 2-acylisoxazol-5-ones

Chemistry of 5-oxodihydroisoxazoles. Part 18.1 Synthesis of oxazoles by the photolysis and pyrolysis of 2-acyl-5-oxo-2,5-dihydroisoxazoles

“…acylation of isoxazol-5(2H)-ones: herein we elaborate our preliminary report 27 on the photolytic and pyrolytic conversion of these species into oxazoles.…”

Route Design in the 21st Century: The ICSYNTH Software Tool as an Idea Generator for Synthesis Prediction

“…Amongst other suggestions, the oxazole 26 is probably best accessed by reductive amination of commercially available formyloxazole 27 and N -crotonoylation. An alternative suggestion from the computer is vapor-phase thermolysis or photolysis of N -acylated isoxazolidinone 28 , itself derived by straightforward N -acylation routes from commercial isoxazolidinone 29 (from acetoacetate and hydroxylamine) . The decarboxylative rearrangement is presumably driven by homolysis of the relatively weak N–O bond in 28 followed by decarboxylation and alternative ring closure of a formal diradical.…”

A comparison of some pyrolysis reactions of benzotriazoles, benzisoxazolones and benzisothiazolones

“…We have commented previously in a general way 1 that the thermal or photochemical decomposition of isoxazol-5(2H )ones 1 is analogous to that of triazoles 2, in that they could both be expected to be sources of iminocarbenes 3. 2 The reported reactions of carbenes 3 from triazoles have generally involved intramolecular rearrangements, 3,4 while those from isoxazolones have been both intramolecular 1,5, 6 and intermolecular 7,8 in nature. We have recently compared the results of flash vacuum pyrolysis (FVP) of N-benzylbenzotriazoles and N-benzylbenzisoxazolones, 9 and the related acyl derivatives, 10 where the modes of decomposition were substantially different.…”