Thermolysis of pyrimido-1, 4-benzothiazine sulfonium ylides caused competitively [1, 2] and [1, 4] rearrangements, or β-elimination, depending upon the natures of the substituents in the ylide moiety. Ultraviolet irradiation of the methyl, ethyl and benzyl sulfonium ylides resulted exclusively in the [1, 2] rearrangement followed by ring expansion leading to pyrimido-1, 4-benzothiazepines. On the basis of some data, the reaction sequences of these rearrangements were discussed.
嘧啶-1,4-苯并
噻嗪锍酰化物的热分解会导致[1,2]和[1,4]竞争性重排或β-消除,这取决于酰化物分子中取代基的性质。紫外线辐照甲基、乙基和苄基锍酰化物只导致[1, 2]重排,然后扩环,生成
嘧啶-1, 4-苯并
硫氮杂卓。根据一些数据,讨论了这些重排的反应顺序。