作者:Takehiko Nishio、Yo-ichi Mori、Ikuo Iida、Akira Hosomi
DOI:10.1039/p19960000921
日期:——
The photochemical reactions of the benzoxazole-2-thiones 6 have been examined. Irradiation of 3-unsubstituted benzoxazole-2-thione 6a in the presence of alkenes 2 gave 2-alkylated benzoxazoles 7, 9–15 and 8 (in the case of 2a). Irradiation of 3-substituted benzoxazole-2-thiones 6b–e and acrylonitrile 2f yielded the 2-alkylidenebenzoxazoles 17, 22 and 24–25. Irradiation of 6b–e in the presence of 1,1-di-and tetra-substituted alkenes 2a,c and e gave the amide derivatives 18–20, 23 and 26. The 3-(alk-ω-enyl)-benzoxazole-2-thiones 6g–i gave the lactam derivatives 28g–i upon irradiation. The formation of these photoproducts can be explained in terms of the intermediacy of amino spiro-thietanes, which are derived by [2 + 2] photocycloaddition of the CS bond of benzoxazole-2-thiones and the CC bond of alkenes.
苯并噁唑-2-硫酮6的光化学反应已被研究。在烯烃2的存在下,3-未取代的苯并噁唑-2-硫酮6a的光照产生了2-烷基化苯并噁唑7、9–15和8(对于2a的情况)。3-取代的苯并噁唑-2-硫酮6b–e和丙烯腈2f的光照生成了2-亚烷基苯并噁唑17、22和24–25。在1,1-二取代和四取代烯烃2a、c和e的存在下,6b–e的光照产生了酰胺衍生物18–20、23和26。3-(烯基)-苯并噁唑-2-硫酮6g–i在光照下生成了内酰胺衍生物28g–i。这些光产物的形成可以通过氨基螺硫醚的中间体来解释,这些中间体是通过苯并噁唑-2-硫酮的CS键和烯烃的CC键的[2 + 2]光环加成反应衍生而来的。