α-(Arylthio)imidoyl Radicals: [3 + 2] Radical Annulation of Aryl Isothiocyanates with 2-Cyano-Substituted Aryl Radicals
作者:Rino Leardini、Daniele Nanni、Patrizia Pareschi、Antonio Tundo、Giuseppe Zanardi
DOI:10.1021/jo971128a
日期:1997.11.1
A novel cascade radical reaction is described involving aryl isothiocyanates and 2-cyanoaryl radicals. The mechanism entails the formation of an alpha-(arylthio)imidoyl radical, a 5-exo-dig cyclization onto a cyano group, and a final 6-membered ring closure of an iminyl radical. The competitive 5-membered spiro-cyclization of the iminyl, leading to an isomeric product, was only observed in the case
描述了涉及芳基异硫氰酸酯和2-氰基芳基的新型级联基反应。该机理需要形成α-(芳硫基)亚氨基基,在氰基上进行5-exo-dig环化反应,以及最终亚胺基的6-元闭环。仅在二取代的芳基异硫氰酸酯的情况下观察到亚胺基的竞争性5元螺环化,导致异构体产物。整个过程涉及一个罕见的[3 + 2]自由基环化的例子,并可以高产率单锅合成四缩氮杂环。