Towards a More Sustainable Photocatalyzed α‐Arylation of Amines: Green Solvents, Catalyst Recycling and Low Loading

Abstract

AbstractA more sustainable and efficient protocol for the photocatalytic α‐amino arylation promoted byfac‐Ir(ppy)3was developed. Three noteworthy results were achieved: i) the replacement of toxic medium DMA with the greener solvents NBP and NHP, and the concurrent improvement of the process efficiency by lowering both the amine and the base amount; ii) the development of a recycling protocol for both the sustainable solvent NHP and the commercially available costly photocatalystfac‐Ir(ppy)3, achieving environmental and economic benefits. This approach to the photocatalyst recovery avoids very demanding catalyst structural modifications; iii) the protocol in green solvents proved to be scalable up to 10 mmol of limiting reagent, maintaining excellent performance also lowering the photocatalyst loading down to 0.05 mol%. This is the first example of photocatalytic α‐arylation of amines promoted by such a low amount of catalyst. Lastly, the versatility of this approach was demonstrated by extending the use of the green solvent NBP to another photoredox process.magnified image