Studies On Efficient Approaches To Aerobic Selenations And Oxygenations Of Organo Compounds

Oxygen,which makes up about a fifth of the air by volume,is a low-cost and green oxidant favoured by chemists.Aerobic oxidation reaction has the advantages of simple operation,high atomic economy and clean?the primary by-product is water or hydrogen peroxide?,which fully conforms to the sustainable development concept and the requirement of green chemistry.Since2008,the development of visible light catalysis has entered“golden age”.A large number of scientific achievements and applications have fully proved that visible light catalysis has become a powerful tool in the field of synthetic chemistry in the development of new and valuable chemical reactions.After the encounter between visible light and air,visible light catalyzed aerobic oxidation reaction came into being and achieved a series of green and energy-saving chemical transformation at room temperature,which has important research value and broad development prospect.This paper focuses on the application and reaction mechanism of visible light catalysis and aerobic oxidation in organic synthesis.The specific contents are as follows:Chapter 1:this chapter summarizes the common mechanism of visible light catalyzed aerobic oxidation,and describes the types of reactive oxygen produced in the reaction system,the redox potential,the types and the reactions involved in forming chemical bonds in turn.In particular,the application of diselenides in visible light aerobic oxidation and the project design are briefly described.Chapter 2:in this chapter,strong electrophilic selenium-?-acid,producing from the oxidation of diselenides by excited photocatalyst,enabled electrophilic addition reaction with unsaturated compounds?such as:unsaturated amides,alcohol,acid and oxime etc.?and afforded a series of seleno heterocycles.Notably,this is the first report for oxazoline selenide synthesis by visible light aerobic oxidation reaction.In addition,the present photochemical approach can efficiently and conveniently realize the gram scale experiment and the synthesis of important value intermediates.Chapter 3:in this chapter,visible light catalytic selenization of electron-rich?heterocyclic?aromatic compounds using air as oxidant has been first reported.Indoles,pyrrole,thiophene,imidazole,phenyl and other aromatic compounds can effectively generate corresponding selenization products.In addition,aromatic,heteroaromatic and aliphatic diselenides containing various substituents can be used as effective selenization reagents for this reaction.Cytotoxicity experiments indicate that some aryl selenides have good antitumor activity.The mechanism study shows that the energy transfer reaction between diselenide compounds and the photocatalyst can effectively inhibit the generation of singlet oxygen,thus leading to high chemical selectivity of the aerobic oxidation reaction.Chapter 4:in this chapter,the electron transfer state formed by organic photocatalyst 9-?2,4,6-trimethylphenyl?-10-methyl acridine salt?Mes-Acr⁺?with high quantum yield after visible light excitation was used to effectively avoid the generation of singlet oxygen,and the oxo-acyloxylation of aryl alkenes was realized with high chemical selectivity.In particular,?-acyloxy ketones can be easily obtained by intramolecular oxo-acyloxylation with5-aryl-4-pentenoic acid as raw material.This strategy provides a cheap,easy accessibility of raw material,mild reaction conditions and environmentally benign solution for the synthesis of?-acyloxy ketones.The reaction mechanism was studied by intermediate captures,spectroscopic and electrochemical experiments and DFT calculations.Chapter 5:in this chapter,2-indoxones underwent effective auto-oxidation with oxygen at room temperature to generate isatin using tetrabutyl ammonium fluoride?TBAF?as a catalyst,and subsequent Aldol reaction with ketones produced valuable 3-hydroxy-3-?2-oxo-alkyl?-2-oxindoles.The method using O₂ as oxidant and without heating provides a green,succinct,practical,and metal-free protocol for the synthesis of 3-hydroxy-3-?2-oxoalkyl?-2-oxindole compounds.Chapter 6:in this chapter summarizes the topic of visible light catalytic aerobic oxidation that I have joined,and prospects of visible light aerobic oxidation and organic selenium chemistry were also articulated.