Photocatalytic Difluoroalkylation And Arylation Of Para-quinone Methides

In the past decade,visible-light photocatalysis has been widely developed and applied.In this domain,visible-light-induced fluoroalkylation is rather prospective.We mainly explored the difluoroalkylation and arylation of para-quinone methides?p-QMs?via visible-light photocatalysis in this thesis.In the first chapter,the general mechanisms of photocatalyst and the common reaction modes of photocatalysis are introduced.Then the reactions of fluoroalkylation?including fluorination,difluoroalkylation,trifluoromethylation and perfluoroalkylation?mediated by photocatalysis is summarized from the reaction substrates aspect:alkanes,alkenes,alkynes,?hetero?arenes,and their derivatives.The second chapter is the main part of this thesis.It describes a visible-light-promoted approach to access the difluoroalkylated diarylmethane compounds,potential biological and pharmacological structure,via radical-radical cross-coupling reactions of p-QMs and difluoroalkylation reagents.Mechanism studies showed that the excited photocatalyst*fac-Ir?ppy?₃ was primarily quenched by p-QMs.In this work,we firstly reported that p-QMs act as diarylmethane radical precursors.In the third chapter,the arylation of p-QMs to achieve triarylmethanes was explored.On the basis of previous work,the reaction conditions were optimized and then the possible reaction mechanism was proposed.