首页 | 本学科首页   官方微博 | 高级检索  
     检索      


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
Authors:Eietsu Hasegawa  Minami Tateyama  Tsuneaki Hoshi  Taku Ohta  Eiji Tayama  Hajime Iwamoto  Shin-ya Takizawa  Shigeru Murata
Institution:1. Department of Chemistry, Faculty of Science, Niigata University, Ikarashi-2 8050, Niigata 950-2181, Japan;2. Department of Basic Science, Graduate School of Arts and Sciences, The University of Tokyo, Meguro-ku, Tokyo, 153-8902, Japan
Abstract:A combination of 2-aryl substituted 1,3-dimethyl-benzimidazolines (DMBIHs) and tris(2,2′-bipyridine)ruthenium(II) chloride, Ru(bpy)3Cl2 was used to promote photoinduced electron-transfer (PET) reactions of α-halomethyl-substituted benzocyclic 1-alkanones. This photo-reagent system stimulates free radical forming, cleavage of both carbon–bromine and carbon–chlorine bonds that are not activated by carbonyl groups. The resulting free radicals 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 pathways followed by the radical intermediates. PET reactions using an iridium complex and DMBIH were also investigated.
Keywords:Photoinduced electron-transfer  Benzimidazoline  Ru complex  α-Halomethyl benzocyclicalkanones  Hexenyl radical cyclization  Dowd&ndash  Beckwith ring-expansion
本文献已被 ScienceDirect 等数据库收录!
设为首页 | 免责声明 | 关于勤云 | 加入收藏

Copyright©北京勤云科技发展有限公司  京ICP备09084417号