An asymmetric phase-transfer-catalyzed N-alkylation of substituted indoles with various Michael acceptors was studied. Acidities of nitroindoles were determined in acetonitrile by UV-Vis spectrophotometric titration. There was essentially no correlation between acidity and reactivity in the aza-Michael reaction. The position of the nitro group on the indole ring was essential to control the stereoselectivity of the reaction. Michael adducts were obtained in high yields and moderate enantioselectivities in the reaction between 4-nitroindole and various Michael acceptors in the presence of cinchona alkaloid based phase-transfer catalysts. In addition to outlining the scope and limitations of the method, the geometries of the transition states of the reaction were calculated.

中文翻译：

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相转移催化下硝基吲哚的对映选择性N-烷基化

研究了具有各种迈克尔受体的取代吲哚的不对称相转移催化的N-烷基化。通过UV-Vis分光光度滴定法测定乙腈中硝基吲哚的酸度。在氮杂-迈克尔反应中，酸度和反应性之间基本上没有相关性。吲哚环上硝基的位置对于控制反应的立体选择性至关重要。在基于金鸡纳生物碱的相转移催化剂存在下，4-硝基吲哚与各种迈克尔受体之间的反应以高收率和中等对映选择性获得迈克尔加合物。除了概述该方法的范围和局限性之外，还计算了反应过渡态的几何形状。