Synthesis of Highly Substituted Indolines and Indoles via Intramolecular [4 + 2] Cycloaddition of Ynamides and Conjugated Enynes
作者:Joshua R. Dunetz、Rick L. Danheiser
DOI:10.1021/ja051180l
日期:2005.4.1
Ynamides react with conjugated enynes in intramolecular [4 + 2] cycloadditions to afford substituted indolines that undergo oxidation with o-chloranil to furnish the corresponding indoles. The cycloaddition substrates are easily assembled from derivatives of 3-butynylamine by Sonogashira coupling with alkenyl halides followed by copper-catalyzed N-alkynylation with acetylenic bromides. Diynamides participate
Ynamides 与共轭烯炔在分子内 [4 + 2] 环加成反应中得到取代的二氢吲哚,该二氢吲哚与邻氯苯醌氧化以提供相应的吲哚。环加成底物很容易从 3-丁炔胺的衍生物通过 Sonogashira 与链烯基卤化物偶联,然后铜催化的 N-炔基化与乙炔溴化物组装而成。二炔酰胺在环加成反应中作为特别活泼的 2pi 组分参与,提供在 C-7 位置获得具有碳取代基的二氢吲哚的途径。烯酰胺在环加成策略的互补版本中用作 4pi 组分,该策略提供了获得在 C-4 处被碳取代基取代的吲哚和二氢吲哚的途径。这些烯炔环加成在 110-210 摄氏度的甲苯或 2,2 中加热基板时发生,