Light-Mediated Organocatalysis with N-Heterocyclic Carbenes

本课题主要研究光照对N-杂环卡宾(NHCS)催化有机反应的影响。NHC-有机催化已经成为一种强有力的工具，可以促进许多合成上重要的和经常是对映体选择性的转化，包括醛衍生物的Upolung反应。尽管近年来取得了很大的进展，但可访问的反应路径的范围在很大程度上仍然限于经典的Aldol类型的过程，人们迫切地寻求涉及不同的非经典路径的新策略，以扩大这一化学的范围。受之前提到的NHCS稳定开壳物种的能力的启发，我们打算研究光照射对NHC催化的羰基化合物反应的影响，主要集中在羧酸和酯底物上。该项目涉及一种新的催化概念，涉及通过光中介激发酰基唑中间体，使传统上对酮进行的经典光化学反应可以使用先前不适合的羧酸衍生物底物进行。将开发这一概念的新催化应用，同时将使用化学计量研究，包括光谱和实验研究，以提供机理洞察和指导反应发展。

This project is focused on investigating the effect of light irradiation on organic reactions catalysed by N-heterocyclic carbenes (NHCs). NHC-Organocatalysis has emerged as a powerful tool that facilitates many synthetically important and often enantioselective transformations including umpolung reactions of aldehyde derivatives. Despite the great advances made in recent years, the range of accessible reaction pathways remains largely limited to classical aldol-type processes and new strategies involving different, non-classical pathways that enhance the scope of this chemistry are highly sought. Inspired by the previously-noted ability of NHCs to stabilise open-shell species, we intend to study the effect of light irradiation on NHC-catalyzed reactions of carbonyl compounds, focusing mostly on carboxylic acid and ester substrates. The project concerns a new catalysis concept involving light-mediated excitation of acyl azolium intermediates that allows classical photochemical reactions conventionally performed on ketones to be conducted using previously unsuitable carboxylic acid derivative substrates. New catalytic applications of this concept will be developed while stoichiometric studies including spectroscopic and experimental investigations will be used to provide mechanistic insight and guide reaction development.