Formation of phenonium ions through anchimeric assistance (neighboring-group participation) of aryl rings has been known since 1949. Although these reactive intermediates have been studied extensively by physical organic chemists, their potential as control elements in synthesis is underutilized. Presented here are our laboratory’s recently reported first examples of regiodivergent openings of nonsymmetrical phenonium ions with chloride nucleophiles. The selectivity of these processes is under reagent control. The reactions are operationally simple and permit the stereospecific synthesis of complex chiral building blocks from readily accessible epoxide starting materials. 1 Introduction 2 Select Examples of Phenonium Ion Methodology 3 Regiodivergent Opening of Nonsymmetrical Phenonium Ions 4 Summary and Outlook

中文翻译：

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重温“苯鎓现象”：非对称苯鎓离子与卤化物亲核试剂的区域发散开环

自 1949 年以来，人们就知道通过芳环的嵌合辅助（邻基参与）形成苯鎓离子。尽管物理有机化学家已经对这些反应性中间体进行了广泛的研究，但它们作为合成控制元素的潜力并未得到充分利用。这里展示的是我们实验室最近报道的第一个非对称苯鎓离子与氯化物亲核试剂区域发散开口的例子。这些过程的选择性受试剂控制。该反应操作简单，允许从容易获得的环氧化物起始材料立体定向合成复杂的手性结构单元。1 介绍 2 选择钆离子方法的例子 3 非对称钆离子的区域发散开环 4 总结和展望