Application Of Ir?ppy?₃ In Visible-Light Catalyzed Inert Carbon-Heteroatom Bonds Cleavage Reaction

As we all know,using visible light,which is a clean energy source,as a driving force for synthetic reactions is significant in both theoretical and applied research.In recent years,visible light catalysis has exhibited unique reactivity and selectivity in the conversion of materials,making it a research hotspot in organic synthesis.The C-F bond is the C-X bond with the shortest bond length in the organic bond.It is the strongest carbon heteroatom bond in nature and the strongest a bond.The current chemical methods for cleaving C-F bonds present many shortcomings while researches on photocatalytic cleavage of C-F bonds are rarely reported.Phenol derivatives are commonly used as substrates for cross-coupling reactions.However,the current methodological studies mainly focused on C-O bonds with relatively weak bond energy,which are easy to activate.Few studies have been reported on the C-OMe bonds of phenol derivatives with significantly higher activation energy.Researches on photocatalytic cleavage of inert C-O bonds in arylallkyl ethers are rarely reported.This paper mainly focused on the reaction performance of fac-Ir?ppy?₃ in the cleavage of inert carbon heteroatom bonds under visible light conditions.This paper is divided into the following aspects:1.Photoredox C-F Quaternary Annulation Catalyzed by a Strongly Reducing Iridium Species.We reported fac-Ir?ppy?₃*-Ir^?-Ir^? photocatalytic cycle involving t-BuOK as the terminal reductant in a visible-light-induced sp² C-F quaternary annulation reaction that proceeds in yields up to 98%.Because of the high activity of the Ir^? catalyst,even at a loading of 50 ppm,the annulation reaction was able to compete with an uncatalyzed nucleophilic aromatic substitution reaction.The annulation reaction was stereoconvergent,and an annulated product was synthesized with complete retention of enantiomeric excess.Substrate control could be used to achieve enantioenriched annulation products by means of the efficient protocol.Intermolecular C-F coupling was also achieved with this catalysis.2.Application of fac-Ir?ppy?₃ in Visible-Light Catalyzed Inert C-O Bond Cleavage ReactionWe have also reported a method for the catalytic cleavage of inert C?sp²?-O bonds in arylalkyl ethers using fac-Ir?ppy?₃ as a photosensitizer under light conditions,while a quaternary carbon center was simultaneously constructed.In the study,aryl alkyl ethers were selected as the substrates.Radicals generated from phenyl 2-bromo-2-methylpropionate under light conditions underwent an addition reaction to the benzene ring,which in turn induced the cleavage of the C-O bond.In this methodology,fac-Ir?ppy?₃ underwent fac-Ir?ppy?₃*-Ir^?-Ir^? photocatalytic cycling.The reaction conditions were mild,simple and rapid,while the scope of the substrates was wide.