Convenient Approaches towards the Synthesis of Novel Pyrano[2,3-<i>a</i>]carbazoles
作者:Kumaresan Prabakaran、Matthias Zeller、Paul S. Szalay、Karam J. Rajendra Prasad
DOI:10.1002/jhet.910
日期:2012.11
Previously not easily accessible pyrano[2,3‐a]carbazoles were synthesized in highly convergent syntheses avoiding multistep procedures from readily available 1‐hydroxycarbazoles. Substituted pyrano[2,3‐a]carbazoles were produced by three different methods by treatment of the 1‐hydroxycarbazoles with dimethyl acetylene dicarboxylate (DMAD) and triphenylphoshine, by reaction with ethyl 2‐methylacetoacetate
以前不易获得的吡喃并[2,3- a ]咔唑是通过高度收敛的合成方法合成的,避免了从容易获得的1-羟基咔唑进行多步操作的过程。取代的吡喃并[2,3- a ]咔唑是通过三种不同的方法生产的,方法是在ZnCl 2 / POCl 3存在下,用乙炔二甲酸二甲酯(DMAD)和三苯基膦与1-甲基乙酰乙酸乙酯反应,处理1-羟基咔唑,通过与三氟乙酸反应,然后与(碳乙氧基亚甲基)三苯基磷烷进行维蒂希反应。本文还着重介绍了优化反应条件和策略的方法,从而避免了所有三种类型反应的副产物形成。