Visible-light Catalyzed Functionalization Of Aryl Halides And Amino Acid Derivatives

Visible-light photocatalysis is of some advantages including high efficiency,green and environmentally friendly and mild reaction conditions in organic synthesis.Recently,the photocatalysis has made great progress in the functionalization of organic compounds.Compared with the traditional transition metal-catalyzed functionalization,visible-light photocatalysis exhibits higher efficiency,milder conditions and more novel reactions.In this dissertation,the functionalizations of aryl haldes and amino acid derivatives were investigated,and the corresponding results were obtained as follows:A general and efficient visible-light photoredox arylation of thiols with aryl halides at room temperature has been developed.The protocol used readily available aryl halides including aryl iodides,bromides,chlorides and fluorides as the arylating reagents,and the corresponding aryl thioethers were prepared in high yields.The reaction mechanism was deeply investigated,and a reasonable process was provided.The present method exhibits tolerance of wide functional groups.More importantly,various aryl chlorides were effective in the arylation of thiols at room temperature,so this is an important breakthrough of aryl chlorides in the chemical transformations.An efficient visible-light photoredox borylation of aryl halides leading to arylboronic acids and esters has been developed at room temperature.The protocol used aryl halides,bis-boronic acid and bis(pinacolato)diboron as the substrates,and the corresponding arylboronic acids and esters were prepared in high yields.Furthermore,various substituted phenols were successfully synthesized via the one-pot two-step strategy.The mechanism study showed that the reaction underwent an aryl radical intermediate process by desorption of halogen anion.The method showed some advantages including simple equipments,mild conditions,easy operation and wide substrate scope.Therefore,the present method provides a valuable strategy for chemical transformations.A novel and efficient approach to unnatural chiral α-amino acids at room temperature under visible-light assistance has been developed.The protocol useed two readily available genetically coded proteinogenic amino acid,L-aspartic acid and glutamic acid derivatives,as the chiral souces and radical precursors,and 83 unnatural chiral α-amino acids containing ketones,esters,amides,alkynes,alkene and phenanthridine on the side chains were prepared in good to excellent yields with excellent tolerance of wide functional groups.The simple protocol,mild conditions,fast reactions,and high efficiency make the method an important strategy for synthesis of diverse unnatural chiral α-amino acids with biological and medicinal activity.