2-Acyl-3-arylisoxazol-5(2H)-ones give
2-alkyl(aryl)-4-aryloxazoles in good yields at 540°C under flash vacuum
pyrolysis conditions, but at higher temperatures the expected oxazoles are
accompanied by increasing amounts of isomeric 2,5-disubstituted oxazoles, as
well as anilides and decomposition products of the 2,4-disubstituted oxazole.
The rearrangement mechanisms have been studied by the use of
13C labelled substrates and
p-substituted 3-arylisoxazolones. The 2,5-disubstituted
oxazoles are considered to arise from 1H-azirines, and
the anilides from the nitrone ketene isomer of the acylisoxazolone.
2-酰基-3-芳基
异噁唑-5(2H)-酮在 540°C 的闪速真空条件下产生
在 540°C 的闪蒸真空热解条件下,可以得到产率很高的 2-烷基(芳基)-4-芳基
噁唑。
但在更高温度下,预期的
噁唑会伴随着越来越多的异构体出现。
但在更高温度下,预期的
噁唑会伴随着越来越多的异构 2,5-二取代
噁唑,以及
苯胺和分解物。
以及
苯胺和 2,4-二取代
噁唑的分解产物。
对重排机理的研究采用了
13C 标记的底物和
对取代的 3-芳基
异噁唑酮。2,5-二取代的
噁唑被认为来自 1H-吖嗪,而
苯胺则来自腈。
苯
胺类则来自酰基
异噁唑酮的腈酮烯异构体。