Development and Applications of Photostable Lewis Basic Isochalcogenourea Catalysts

Objective

In recent years applications of photocatalysis have developed rapidly, with the use of an abundant, cheap energy source (the sun or ambient light) combined with the development of tunable photocatalysts, allowing the facile generation of radicals via single electron transfer or excited state intermediates via energy transfer. Organocatalysis uses small organic molecules to promote enantioselective reactions and has been widely applied over the last two decades for the synthesis of enantioenriched products, with the 2022 Nobel Prize for Chemistry awarded for demonstrating the power of this methodology by MacMillan and List. Combining these two methods in dual catalytic transformations has been demonstrated, however the ability to promote such transformations that utilise abundant and cheap feedstock chemicals at the carboxylic acid oxidation level is a significant challenge, typically requiring tertiary amine Lewis base catalysts. However, utilising enantiopure tertiary amines with photocatalytic transformations is currently limited, due to the facile oxidation and subsequent degradation of the tertiary organocatalyst by the excited state photocatalyst. In this context. this proposal will: 1. Deliver a scalable route to conformally constrained photostable isochalcogneourea catalysts based upon conformationally locked bicyclic catalysts that do not allow traditional oxidative degradation. 2. Utilise these isochalcogneourea catalysts to develop a dual photocatalytic isomerization of (E)-enone acids to their contra-thermodynamic (Z)-isomers followed by isochalcogenourea promoted acylative DKR for the synthesis of fine chemical products. This will be applied to the synthesis of 5- and 7 membered ring compounds as well as the synthesis of planar chiral species.