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Modular Photocatalytic Synthesis of α-Trialkyl-α-Tertiary Amines
Journal of the American Chemical Society ( IF 14.4 ) Pub Date : 2021-09-22 , DOI: 10.1021/jacs.1c07402 J Henry Blackwell 1 , Georgia R Harris 1 , Milo A Smith 1 , Matthew J Gaunt 1
Journal of the American Chemical Society ( IF 14.4 ) Pub Date : 2021-09-22 , DOI: 10.1021/jacs.1c07402 J Henry Blackwell 1 , Georgia R Harris 1 , Milo A Smith 1 , Matthew J Gaunt 1
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Molecules displaying an α-trialkyl-α-tertiary amine motif provide access to an important and versatile area of biologically relevant chemical space but are challenging to access through existing synthetic methods. Here, we report an operationally straightforward, multicomponent protocol for the synthesis of a range of functionally and structurally diverse α-trialkyl-α-tertiary amines, which makes use of three readily available components: dialkyl ketones, benzylamines, and alkenes. The strategy relies on the of use visible-light-mediated photocatalysis with readily available Ir(III) complexes to bring about single-electron reduction of an all-alkyl ketimine species to an α-amino radical intermediate; the α-amino radical undergoes Giese-type addition with a variety of alkenes to forge the α-trialkyl-α-tertiary amine center. The mechanism of this process is believed to proceed through an overall redox neutral pathway that involves photocatalytic redox-relay of the imine, generated from the starting amine-ketone condensation, through to an imine-derived product. This is possible because the presence of a benzylic amine component in the intermediate scaffold drives a 1,5-hydrogen atom transfer step after the Giese addition to form a stable benzylic α-amino radical, which is able to close the photocatalytic cycle. These studies detail the evolution of the reaction platform, an extensive investigation of the substrate scope, and preliminary investigation of some of the mechanistic features of this distinct photocatalytic process. We believe this transformation will provide convenient access to previously unexplored α-trialkyl-α-tertiary amine scaffolds that should be of considerable interest to practitioners of synthetic and medicinal chemistry in academic and industrial institutions.
中文翻译：
α-三烷基-α-叔胺的模块化光催化合成
显示 α-三烷基-α-叔胺基序的分子提供了进入生物相关化学空间的重要和多功能领域的途径，但通过现有的合成方法难以进入。在这里，我们报告了一种操作简单的多组分方案，用于合成一系列功能和结构多样的 α-三烷基-α-叔胺，该方案利用三种容易获得的组分：二烷基酮、苄胺和烯烃。该策略依赖于使用可见光介导的光催化与现成的 Ir(III) 配合物，将全烷基酮亚胺物种单电子还原为 α-氨基自由基中间体；α-氨基自由基与多种烯烃进行 Giese 型加成，形成 α-三烷基-α-叔胺中心。该过程的机理被认为是通过整个氧化还原中性途径进行的，该途径涉及亚胺的光催化氧化还原中继，该亚胺由起始的胺-酮缩合产生，一直到亚胺衍生产物。这是可能的，因为中间支架中苄胺组分的存在驱动了 Giese 加成后的 1,5-氢原子转移步骤，形成稳定的苄基 α-氨基自由基，从而能够关闭光催化循环。这些研究详细介绍了反应平台的演变、对底物范围的广泛研究以及对这种独特光催化过程的一些机械特征的初步研究。
更新日期：2021-10-06
中文翻译：
α-三烷基-α-叔胺的模块化光催化合成
显示 α-三烷基-α-叔胺基序的分子提供了进入生物相关化学空间的重要和多功能领域的途径，但通过现有的合成方法难以进入。在这里，我们报告了一种操作简单的多组分方案，用于合成一系列功能和结构多样的 α-三烷基-α-叔胺，该方案利用三种容易获得的组分：二烷基酮、苄胺和烯烃。该策略依赖于使用可见光介导的光催化与现成的 Ir(III) 配合物，将全烷基酮亚胺物种单电子还原为 α-氨基自由基中间体；α-氨基自由基与多种烯烃进行 Giese 型加成，形成 α-三烷基-α-叔胺中心。该过程的机理被认为是通过整个氧化还原中性途径进行的，该途径涉及亚胺的光催化氧化还原中继，该亚胺由起始的胺-酮缩合产生，一直到亚胺衍生产物。这是可能的，因为中间支架中苄胺组分的存在驱动了 Giese 加成后的 1,5-氢原子转移步骤，形成稳定的苄基 α-氨基自由基，从而能够关闭光催化循环。这些研究详细介绍了反应平台的演变、对底物范围的广泛研究以及对这种独特光催化过程的一些机械特征的初步研究。
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