Annulation of aromatic imines via directed C-H activation with Wilkinson's catalyst
Annulation of aromatic imines via directed C-H activation with Wilkinson's catalyst
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DOI：
10.1021/ja016642j
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发表时间：
2001-10-03
影响因子：
15
通讯作者：
Ellman, JA
中科院分区：
文献类型：
--
作者：
Thalji, RK;Ahrendt, KA;Ellman, JA
应用过渡金属介导的CH活化CC键的形成具有很大的潜力，从简单的起始原料制备复杂的产品。[1]这种转化的第一个例子是Murai的区域选择性的正离子催化的芳族酮与烯烃的邻位烷基化反应，这被认为涉及邻位位点的杂原子定向CH活化。2 Brookhart已经使用Cp* Rh（C2 H3-SiMe 3）2（Cp*）C5 Me 5）以相当的效率催化该反应，3a和几个小组现在已经扩大了这些方法的范围，以包括其他定向基团，如亚胺、酯和吡啶。然而，这些反应仅得到线性偶联产物，并且通常限于不带有烯丙基氢的末端烯烃。最近，Jun报道了一个更一般的亚胺定向偶联反应，使用威尔金森的催化剂[（PPh 3）3RhCl]，它容忍内部双键，但只产生线性产物。4我们的小组一直对这种方法的分子内变体感兴趣，最近报道了烯基取代的杂环衍生物的成环。在本文中，我们提出了芳族亚胺的环化，其中烯烃被间位栓Meta到亚胺（等式1）。偶联选择性地进行到更受阻的邻位，以提供难以通过其他方法获得的官能化双环系统。这种分子内反应可以提供线性或支化的偶联产物，具体取决于烯系链。我们的研究结果表明，第一次烯丙基醚和烯丙基胺衍生物的功能作为有效的烯烃偶联合作伙伴的定向CH活化反应。值得注意的是，与使用威尔金森催化剂的分子间变体4相反，醛亚胺充当有效的导向基团。6
The application of transition metal-mediated CH activation to CC bond formation has great potential for the preparation of complex products from simple starting materials. 1 One of the first examples of such a transformation is Murai’s regioselective ruthenium-catalyzed ortho alkylation of aromatic ketones with alkenes, which is proposed to involve heteroatom-directed CH activation of the ortho-site. 2 Brookhart has used Cp* Rh (C2H3-SiMe3) 2 (Cp*) C5Me5) to catalyze this reaction with comparable efficiency, 3a and several groups have now expanded the scope of these methodologies to include other directing groups such as imines, esters, and pyridines. 3b-e These reactions, however, give only linear coupling products and are typically limited to terminal alkenes bearing no allylic hydrogens. Recently, Jun reported a more general imine-directed coupling reaction using Wilkinson’s catalyst [(PPh3) 3RhCl], that tolerates internal double bonds, yet yields only linear products. 4Our group has been interested in intramolecular variants of this methodology and recently reported the annulation of alkenylsubstituted heterocyclic derivatives. 5 Herein, we present the annulation of aromatic imines in which the alkene is tethered meta to the imine (eq 1). Coupling proceeds selectively to the more hindered ortho site to provide functionalized bicyclic ring systems that would be difficult to access by other methods. This intramolecular reaction can provide linear or branched coupling products depending on the alkene tether. Our results demonstrate for the first time that allyl ethers and allylamine derivatives function as efficient olefin coupling partners for the directed CH activation reaction. Remarkably, in contrast to the intermolecular variant employing Wilkinson’s catalyst, 4 an aldimine serves as an effective directing group. 6