Published as part of the Bürgenstock Special Section 2017 Future Stars in Organic Chemistry

Abstract

Herein, we give a full account of the development of the palladium­-catalysed cross-coupling of benzylammonium salts with boronic acids. A range of benzylamine-derived quaternary ammonium salts can be coupled with boronic acids under relatively mild conditions. Our optimization has identified ligands that can be used to chemoselectively cross-couple at the ammonium in the presence of chlorides. We demonstrate that intramolecular palladium-catalysed C–H activation is also a viable pathway for the putative benzyl-Pd(II) intermediate obtained upon oxidative addition and have optimised this to obtain fluorene in good yield.

Herein, we give a full account of the development of the palladium­-catalysed cross-coupling of benzylammonium salts with boronic acids. A range of benzylamine-derived quaternary ammonium salts can be coupled with boronic acids under relatively mild conditions. Our optimization has identified ligands that can be used to chemoselectively cross-couple at the ammonium in the presence of chlorides. We demonstrate that intramolecular palladium-catalysed C–H activation is also a viable pathway for the putative benzyl-Pd(II) intermediate obtained upon oxidative addition and have optimised this to obtain fluorene in good yield.

中文翻译：

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轻度条件下钯催化的苄基铵盐与硼酸的交叉偶联

作为Bürgenstock专栏2017年有机化学中的未来之星的一部分发布

抽象的

在本文中，我们充分考虑了钯催化的苄基铵盐与硼酸的交叉偶联的发展。一系列苄胺衍生的季铵盐可以在相对温和的条件下与硼酸偶联。我们的优化确定了可用于在氯化物存在下在铵上进行化学选择性交联的配体。我们证明了分子内钯催化的C–H活化也是氧化加成后推定的苄基-Pd（II）中间体的可行途径，并对其进行了优化，从而以良好的收率获得了芴。

在本文中，我们充分考虑了钯催化的苄基铵盐与硼酸的交叉偶联的发展。一系列苄胺衍生的季铵盐可以在相对温和的条件下与硼酸偶联。我们的优化确定了可用于在氯化物存在下在铵上进行化学选择性交联的配体。我们证明了分子内钯催化的C–H活化也是氧化加成后推定的苄基-Pd（II）中间体的可行途径，并对其进行了优化，从而以良好的收率获得了芴。