The Construction Of Heterocycles Via Visible-Light Photoredox Catalysis

Heterocycles represent the most important class of organically active molecules that are frequently encountered in biologically active natural products,pharmaceuticals.Therefore,the synthesis of heterocycles is still highly important and attractive in synthetic community.A good deal of catalytic strategies have been established to assemble structurally manifold heterocycles.For the past few years,visible-light photocatalysis has received a growing number of attention from the synthetic community on account of its characteristic activation patterns and importance for sustainable chemistry.In recent years,visible light has been a hotspot in organic synthesis,as it is pollution-free,low-cost,inexhaustible.With growing knowledge of photoredox catalysis promoted by visible light,the application of this protocol in organic synthesis has been rapidly developed.Although photoredox catalysis endowed many reactions with mild conditions,the utilization of visible light is limited enormously owing to that it cannot be absorbed by most of organic moleculars.Phototcatalyst,which engaged in single-electron-transfer(SET)or energy transfer process with organic substrates upon excitation with visible light,has made the use of visible light in organic synthesis reach its climax.In this paper,we mainly introduce the background and mechasim of visible-light catalysis,summarize the traditional methods for heterocycles,emphasize on our new strategies for the synthesis of biaryl sultams,polysubstituted furans and a-amino ketones.This thesis includes the following four parts:The chapter 1 summarized the background of visible-light photoredox catalysis,application and research progress of heterocycles.The chapter 2 introduced the synthesis of biaryl sultams.We realized the intramolecular denitrogenative cyclization of triazine derivatives under visible light photoredox catalysis systematically.The chapter 3 was about the synthesis of tetrasubstituted furans using photoredox catalyzed coupling of 2-bromo-1,3-dicarbonyl compounds with silyl enol ethers.2-Bromo-1,3-dicarbonyl compounds as radical donor can couple with silyl enol ether as electron-rich radical acceptors under visible light irradiation and photocatalyst to complete the reaction.The last part mainly elaborated the oxidative amidation of styrenes to prepare a-amino ketones.Photoredox-catalyzed difunctionalizations of alkenes with O-acyl hydroxylamine derivatives have been described.Oxidative amidation of alkenes can be achieved in DMSO.A variety of a-amino ketones bearing many functional groups are prepared using Ir(ppy)3 as the photocatalyst under visible light irradiation.