Carbanions for synthesis by photoinduced sequential multi-electron transfer

通过光诱导连续多电子转移合成碳负离子

• 批准号: 361478827
• 负责人: Professor Dr. Burkhard König
• 金额: --
• 依托单位: Institut für Organische Chemie
• 依托单位国家: 德国
• 项目类别: Reinhart Koselleck Projects
• 财政年份: 2017
• 资助国家: 德国
• 起止时间: 2016-12-31 至 2023-12-31
• 项目状态: 已结题
• 来源: https://gepris.dfg.de/gepris/projekt/361478827?language=en
• 关键词: Carbanions; synthesis; photoinduced; sequential; multi

Visible light photoredox catalysis has developed into a valuable method for organic synthesis over the last decade. The key step is the photo-induced transfer of one electron from a redox active photocatalyst to a substrate triggering its chemical conversion. In most cases radical reactions are initiated, which limits a broader application in organic synthesis.The aim of this project is to extend visible light photoredox catalysis to ionic reactions, particular to the in situ generation of carbanions. Carbanions are key intermediates in synthesis and one typical preparation is the reduction of organohalides with metals, such as magnesium giving Grignard reagents. Using metals as the stoichiometric electron donor is energy intensive and generates pyrophoric intermediates although the metal is not retained in the final organic product. Replacing metal reduction by visible light induced multi-electron transfer should allow the in situ preparation of carbon nucleophiles with unprecedented energy efficiency at mild reaction conditions. A new carbanion chemistry without metals may be imagined. To achieve this goal, we use our previously established method accumulating the energy of two visible light photons generating strongly reductive potentials. Stepwise direct or mediated photo-induced transfer of two electrons combined with the loss of an anionic leaving group or protonation converts organohalides or alkenes, respectively, into their corresponding carbanions.

在过去的十年中，可见光光电毒素催化已发展为有机合成的宝贵方法。关键步骤是将一个电子从氧化还原活性光催化剂转移到触发其化学转化的底物的光诱导转移。在大多数情况下，启动了根本反应，这限制了有机合成中更广泛的应用。该项目的目的是将可见光光光毒素催化扩展到离子反应，尤其是对碳纤维的原位产生。 Carbanions是合成中的关键中间体，一个典型的制剂是用金属（例如镁给出grignard试剂）减少有机甲烷。尽管金属未保留在最终有机产品中，但使用金属作为化学计量电子供体是能量密集型的，并产生热量中间体。通过可见光诱导的多电子转移代替金属还原应允许在轻度反应条件下以前所未有的能源效率原位制备碳接核器。可以想象一种没有金属的新碳化化学反应。为了实现这一目标，我们使用先前建立的方法积累了两个可见光光子的能量，产生了强大的还原电位。逐步直接或介导的光诱导的两个电子的传递以及阴离子离开组或质子化的损失分别将有机甲烷或烷烃转化为相应的碳纤维。