A photo-reagent system of benzimidazoline and Ru(bpy)3Cl2 to promote hexenyl radical cyclization and Dowd–Beckwith ring-expansion of α-halomethyl-substituted benzocyclic 1-alkanones
作者:Eietsu Hasegawa、Minami Tateyama、Tsuneaki Hoshi、Taku Ohta、Eiji Tayama、Hajime Iwamoto、Shin-ya Takizawa、Shigeru Murata
DOI:10.1016/j.tet.2014.02.078
日期:2014.4
undergo 5-exo hexenyl cyclization as well as sequential cyclization and ring-expansion (Dowd–Beckwith) reactions to form radicals that abstract hydrogen atoms from the radical cation of DMBIH to yield the observed products. The results of a study of the effects of substituents located on the 2-aryl ring of DMBIH suggest that steric and hydrogen-bonding interactions influence the nature of the reaction
2-芳基取代的1,3-二甲基苯并咪唑啉(DMBIHs)和氯化三(2,2'-联吡啶)钌(II),Ru(bpy)3 Cl 2的组合用于促进光致电子转移(PET )α-卤代甲基取代的苯并环1-链烷酮的反应。这种光试剂系统可刺激自由基的形成,即未被羰基活化的碳溴键和碳氯键的裂解。产生的自由基经历5- exo己烯基环化以及顺序环化和扩环(Dowd-Beckwith)反应形成自由基,该自由基从DMBIH的阳离子中提取氢原子,从而产生可观察到的产物。对位于DMBIH的2-芳基环上的取代基的影响的研究结果表明,空间和氢键相互作用会影响反应途径的性质,进而影响自由基中间体的作用。还研究了使用铱配合物和DMBIH的PET反应。