Photon-Quantitative 6π-Electrocyclization of a Diarylbenzo[<i>b</i>]thiophene in Polar Medium
作者:Ruiji Li、Takuya Nakashima、Olivier Galangau、Shunsuke Iijima、Rui Kanazawa、Tsuyoshi Kawai
DOI:10.1002/asia.201500328
日期:2015.8
and highly efficient photocyclization of 2,3‐diarylbenzo[b]thiophenes with nonsymmetric side‐aryl units in a polar solvent. While the dithiazolylbenzo[b]thiophene showed a suppressed quantum yield of 6π‐electrocyclization of 54 % in methanol, the replacement of a thiazole unit with a thiophene ring led to a photon‐quantitative 6π‐cyclization reaction. The nonsymmetrical modification into the side‐aryl
极性溶剂中6π电环化的高反应性仍然是二芳烃的重要挑战之一,因为在这种极性介质中,在激发态下会出现扭曲的分子内电荷转移(TICT)状态,这通常会终止光环化反应。在此,我们报告了极性溶剂中具有不对称侧芳基单元的2,3-二芳基苯并[ b ]噻吩的制备及其高效光环化反应。而二噻唑基苯并[ b]噻吩在甲醇中的6π电环化显示抑制的量子产率为54%,噻唑单元被噻吩环取代导致光子定量6π环化反应。考虑到对侧芳基单元的非对称修饰可增强侧芳基单元之间的CH /π相互作用,以支持甲醇中的光反应性构象。期望光致变色反应构象的稳定化将抑制在激发态下TICT状态的形成,从而导致高效的光反应性。