3-Isoxazolones 2-oxazolones

Cyclic carbonates react with primary amines to give /3-oxo carbamates which are dehydrated to 2(3//)-oxazolones (equation 141). Thermal rearrangement of the isoxazolone (290) results in the oxazolone (291 equation 142). 

Deng, B. L., Hartman, T. L., Buckheit, R. W, Jr, Pannecouque, C., De Clercq, E., Cushman, M. Replacement of the metabolically labile methyl esters in the alkenyldiarylmethane series of non-nucl-eoside reverse transcriptase inhibitors with isoxazolone, isoxazole, oxazolone, or cyano substituents. J. Med. Chem. 2006, 49(17), 5316-5323. 

Hydrazino-5,6-diphenyl-l,2,4-triazine (289) reacts with 4-benzylidene-2-phenyl-5(4//)-oxazo-lones (290) and 4-benzylidene-3-methyl-5(4//)-isoxazolones (291) in toluene to products (292), (293) substituted in the hydrazino group, the first by acylation by the oxazolone, the second by arylraethylidene group transfer (Scheme 53) <88JHC1813>. 

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