(λ(irr) = 313 nm) under neutral and basic conditions; subsequent exposure to visible light reversed the reaction. Under ambient light and in the presence of base, the imidazolium species catalyzed transesterifications as well as amidations in a manner similar to those of previously reported N-heterocyclic carbene precatalysts. However, upon UV irradiation to effect the aforementioned photocyclization
发现 4,5-二
噻吩基
咪唑鎓盐在中性和碱性条件下暴露于紫外线辐射 (λ(irr) = 313 nm) 时会发生电环异构化;随后暴露在可见光下逆转了反应。在环境光和碱存在下,
咪唑鎓物种以类似于先前报道的 N-杂环卡宾预催化剂的方式催化酯交换和酰胺化。然而,在紫外线照射以实现上述光环化作用时,
醋酸乙烯酯和
烯丙醇之间的酯交换反应速率显着减弱(k(vis / UV)= 12.5),
乙酸乙酯与
氨基
乙醇的缩合速率也是如此( k(可见光/紫外线)= 100)。