IonPairEnantRadical : Transforming Enantioselective Radical Chemistry using Ion Pairing Catalysis

自由基反应是电子单独运动而不是成对运动的反应，近年来得到了巨大的发展。这些令人兴奋的发展，其中许多产生了立体中心，突出了使自由基反应具有对映选择性的持续挑战。虽然来自双电子世界的许多关键的对映控制策略已经被应用，但这些策略在许多情况下都是无效的，并且每种策略都有特定的限制。我们对一种利用催化剂和底物之间有吸引力的非共价相互作用来拉近两者并更好地控制运动的催化方法感兴趣。特别是，离子配对是最基本和最强大的非共价相互作用之一，但通常被合成化学家作为一种控制力量探索不足，可能是由于对方向性和可预测性的担忧。然而，我们认为，它们提供了独特的机会，可以在常规策略失效的地方实施选择性控制。在这项提案中，我们概述了一个雄心勃勃的计划，该计划将应用创新的和未探索的离子对策略来控制各种重要的自由基化学中的对映选择性，这些自由基化学没有或有限的现有方法来施加控制。在涉及光氧化还原催化的催化循环中，虽然通常在中间体上适当地指示电荷，但在大多数报告中很少描述甚至尝试跟踪相关的反离子。我们认为，反离子远不是微不足道的，它可以在控制对映体选择性方面发挥关键作用--在一个几乎没有利用现有不对称催化模式的空间的催化循环中，反离子可以提供关键。该提案包括四个工作计划所界定的四个“挑战领域”。这些代表了重要的和热门的激进转变类别，几乎没有先例可以使用现有的方法不对称地进行。如果这里概述的方法可以被证明是可行的，那么还有许多其他类型的反应可以应用，我们希望这可能会在该领域开辟新的地平线。

Radical reactions, in which electrons move singly rather than in pairs, have seen an immense pace of development in recent years. These exciting developments, many of which produce stereocentres, have served to highlight the ongoing challenge of rendering radical reactions enantioselective. Whilst many of the key enantiocontrol strategies from the two-electron world have been applied, these are ineffective in many situations and each strategy possesses specific limitations. We are broadly interested in an approach to catalysis that utilises attractive non-covalent interactions between catalyst and substrate to draw the two close and better exercise control. Particularly, ion-pairing is one of the most fundamental and powerful non-covalent interactions but is frequently underexplored by synthetic chemists as a controlling force, perhaps due to concerns regarding directionality and predictability. However, we believe that they present unique opportunities to exert selectivity control where conventional strategies fail. In this proposal we outline an ambitious program which will apply innovative and unexplored ion-pairing strategies to control enantioselectivity in a variety of important radical chemistries for which there are no or limited existing methods for imposing control. In catalytic cycles involving photoredox catalysis, whilst charge is usually appropriately indicated on intermediates, the associated counterion is rarely depicted or even attempted to be tracked in most reports. We believe that, far from being insignificant, counterions can play crucial roles in the control of enantioselectivity - in a catalytic cycle where there is little scope for leveraging existing modes of asymmetric catalysis, the counterion can provide the key. This proposal consists of four "challenge areas", as defined in the four Work Plans. These represent important and topical classes of radical transformations that have little or no precedent to be carried out asymmetrically using existing approaches. If the approaches outlined herein can be proven viable then there are numerous other reaction types to which they can be applied and we hope that this may open new horizons in the field.