[4 + 2]-Cycloaddition Reactions between β-Acceptor-Substituted Enamines and 2-Vinylindole Radical Cations Acting as Hetero-Dienes
作者:Christoph F. Gürtler、Eberhard Steckhan、Siegfried Blechert
DOI:10.1021/jo951551o
日期:1996.1.1
[4 + 2]-Cycloaddition reactions between 2-vinylindoles acting as hetero-dienes and beta-acceptor substituted cyclic and acyclic enamines can be induced by formation of 2-vinylindole radical cations either via anodic oxidation or photoelectron transfer (PET) using catalytic amounts of triarylpyrylium tetrafluoroborates as sensitizers. In this way, pyrido[1,2-a]indoles or indolo[1,2-a]hexahydro-1,8-naphthyridines
充当杂二烯的2-乙烯基吲哚与β-受体取代的环状和无环烯胺之间的[4 + 2]-环加成反应可以通过使用催化量的阳极氧化或光电子转移(PET)形成2-乙烯基吲哚自由基阳离子来诱导四氟硼酸三芳基吡啶鎓作为敏化剂。以此方式,在完整的区域和立体化学控制下,一步形成吡啶并[1,2-a]吲哚或吲哚[1,2-a]六氢-1,8-萘啶。