Synthesis of a 7-Azaindole by Chichibabin Cyclization: Reversible Base-Mediated Dimerization of 3-Picolines
作者:Yun Ma、Sean Breslin、Ivan Keresztes、Emil Lobkovsky、David B. Collum
DOI:10.1021/jo801410s
日期:2008.12.19
The lithium diisopropylamide (LDA)-mediated condensation of 2-fluoro-3-picoline and benzonitrile to form 2-phenyl-7-azaindole via a Chichibabin cyclization is described. Facile dimerization of the picoline via a 1,4-addition of the incipient benzyllithium to the picoline starting material and fast 1,2-addition of LDA to benzonitrile cause the reaction to be complex. Both adducts are shown to reenter
描述了二异丙基氨基锂 (LDA) 介导的 2-氟-3-甲基吡啶和苄腈缩合反应,通过 Chichibabin 环化反应形成 2-苯基-7-氮杂吲哚。通过初始苄基锂与甲基吡啶原料的 1,4-加成和 LDA 与苯甲腈的快速 1,2-加成使甲基吡啶二聚化反应变得复杂。两种加合物都显示重新进入反应坐标以产生所需的 7-氮杂吲哚。通过 IR 和 NMR 光谱的组合研究了关键中间体的溶液结构和潜在的反应机制。