A Direct Intramolecular C−H Amination Reaction Cocatalyzed by Copper(II) and Iron(III) as Part of an Efficient Route for the Synthesis of Pyrido[1,2-<i>a</i>]benzimidazoles from <i>N</i>-Aryl-2-aminopyridines
作者:Honggen Wang、Yong Wang、Changlan Peng、Jiancun Zhang、Qiang Zhu
DOI:10.1021/ja1067993
日期:2010.9.29
A novel and efficient synthesis of pyrido[1,2-a]benzimidazoles through direct intramolecular aromatic C-H amination of N-aryl-2-aminopyridines has been developed. The reaction, cocatalyzed by Cu(OAc)(2) and Fe(NO(3))(3)·9H(2)O, is carried out in DMF under a dioxygen atmosphere. Diversified pyrido[1,2-a]benzimidazoles containing various substitution patterns are obtained in moderate to excellent yields
已经开发了一种通过 N-芳基-2-氨基吡啶的直接分子内芳香族 CH 胺化来合成吡啶并 [1,2-a] 苯并咪唑的新型高效合成方法。该反应由 Cu(OAc)(2) 和 Fe(NO(3))(3)·9H(2)O 共同催化,在双氧气氛下在 DMF 中进行。使用该方法可以以中等至极好的收率获得含有各种取代模式的多样化吡啶并[1,2-a]苯并咪唑。机理研究结果表明,Cu(III) 催化的亲电芳香取代 (S(E)Ar) 途径在此过程中起作用。铁 (III) 的独特作用被认为在于它能够促进更具亲电性的铜 (III) 物质的形成。在没有铁 (III) 的情况下,会发生效率低得多且可逆的 Cu(II) 介导的 S(E)Ar 过程。