Merging Hydrogen Borrowing/Transfer Catalysis with Photochemistry

本项目福尔斯属于EPSRC合成有机化学研究领域，借氢催化（HBC）已成为合成复杂分子的一种强有力的催化方法。一锅氧化-还原顺序具有固有的高原子经济性，并且使用醇（或胺）作为原料分子的烷基化反应导致产生有价值的产物和作为唯一副产物的水（或氨）。这使得HBC成为传统烷基化化学的绿色替代品。不幸的是，HBC通常需要高的操作温度，导致相对于感兴趣的有机分子的其他敏感部分的选择性差（差的官能团耐受性）。另一种在不使用高温的情况下为反应提供足够能量进行的方法是使用高能照射或来自可见光介导的照射。可见光介导的照射（PC）已经成为有机分子的高能紫外光照射的强大且更安全的替代方法。紫外线照射是非常苛刻的，具有差的官能团耐受性，这意味着它不适合作为一种通用方法-可见光是显着更安全的操作和更具选择性。虽然已经探索了许多类型的化学方法，可以从HBC中拦截短寿命氧化分子的产生，但使用光化学来这样做还没有。在这个项目中，我们将致力于联合收割机这两种技术，通过串联氢借用/转移光化学反应来生产复杂的有机分子。从而获得新的化学反应性，同时也避免了HBC通常的苛刻条件，创造了一种更普遍和适用的方法，可用于制药或农业化学界。首先，我们将研究新的反应模式，例如创造一种短寿命分子的可行性，该分子通过氢借用事件（氧化或还原）对PC具有活性。这种分子可以被光催化剂激发，并在最终的氢借用事件（还原或氧化）完成催化循环之前与其他有机分子发生反应。类似地，我们将寻求开发原则上可以执行氢借用事件和有机分子的光化学激发的催化剂。据我们所知，还没有研究小组考虑将HBC和PC合并，这在原则上可以改变氢借用化学的前景，除了发现新的化学反应性。

This project falls within the EPSRC Synthetic Organic Chemistry research area.Hydrogen borrowing catalysis (HBC) has emerged as a powerful catalytic method for the synthesis of complex molecules. The one-pot oxidation-reduction sequence has an intrinsic high atom economy and alkylation reactions using alcohols (or amines) as feedstock molecules lead to the production of valuable products and water (or ammonia) as the sole by-product. This presents HBC as a green alternative to traditional alkylation chemistry. Unfortunately, HBC typically requires high operating temperatures, leading to poor selectivity with respect to other sensitive parts of the organic molecule of interest (poor functional group tolerance). An alternative way of giving a reaction enough energy to proceed without using such high temperatures is by using high-energy irradiation or from visible light- mediated photocatalysis.Visible light-mediated photocatalysis (PC) has emerged as a powerful and safer alternative to high energy ultra violet light irradiation of organic molecules. Ultra-violet irradiation is extremely harsh and has poor functional group tolerance, meaning it is not suitable as a general method - visible light is significantly safer to operate with and more selective. Although many types of chemistry which can intercept the production of a short-lived oxidised molecules from HBC have been explored, using photochemistry to do so has not. In this project we will aim to combine the two technologies to produce complex organic molecules via tandem hydrogen borrowing/transfer photochemical reactions. Thereby deriving new chemical reactivity and also looking to avert the typically harsh conditions of HBC, creating a more generalised and applicable method which could be used by the pharmaceutical or agrochemical communities.First we will investigate new modes of reactivity, such as the feasibility of creating a short-lived molecule, which is active to PC from a hydrogen-borrowing event (oxidation or reduction). This molecule could be excited by a photocatalyst and undergo a reaction with other organic molecules before a final hydrogen borrowing event (reduction or oxidation) can complete the catalytic cycle. Similarly, we will look to develop catalysts which could in principle perform both the hydrogen borrowing events and photochemical excitation of the organic molecules. To our knowledge, no groups have looked to merge HBC and PC, which in principle could transform the landscape of hydrogen borrowing chemistry in addition to discovering novel chemical reactivity.