Visible-light-promoted Photocatalyst-free Aerobic Cross-dehydrogenative Coupling Of Tertiary Amines To Carbonyls

The reaction between tertiary amines and carbonyl compounds has been a hot topic for chemists.The direct oxidative cross-dehydrogenative coupling(CDC)of two carbon-hydrogen bonds can be an efficient and relatively clean strategy in organic synthesis.In all these reactions,the development of enantioselective catalysis remains a challenge.Recently,although asymmetric catalytic reactions of tertiary amines and carbonyl compounds have made more and more breakthroughs in the field of organic synthesis,there are still series of problems that need to be solved urgently.In recent years,photocatalytic reactions have been a hotspot for chemists under certain photosensitizer conditions,such as Ru,Ir,Au,Cu,and Ni complexes,organic dyes.With the development of the concept of green chemistry,the development of a greener,more economical synthetic method and the asymmetric cross-deoxy coupling reaction of tertiary amines with carbonyl compounds requires more efforts from chemists.Based on above,we have developed a visible light-catalyzed reaction of tertiary amines with carbonyl compounds without the participation of photosensitizers,and achieved good results.This dissertation is focused on the visible light-catalyzed reaction of tertiary amines with carbonyl compounds without the photosensitizers,it includes two chapters:The first chapter we proposed that visible-light excites substrates and products,which further activates oxygen,and ¹O₂ reactivates the substrate to promote asymmetric CDC reactions based on our laboratory's research on green catalytic synthesis and the related work of Wang Group.The mechanism investigation and data analysis of the reaction were carried out by electronic paramagnetic experiments(EPR)and mechanism control experiments.In order to explore the applicability of the substrate,different tertiary amine substrates with various aldehydes were extensively investigated.This method can achieve excellent yields and higher enantiomeric excesses(ee value).In the second section:In combination with the previous work,we will interest a new reaction mode triggered by an electron donor-acceptor(EDA)complex of N-aryl tertiary amines and?,?-unsaturated carbonyl compound.Wide substrate scope and easy scaling up of the reaction make this method more practical in organic synthesis.Photochemical characterization,mechanistic studies and mechanism inference suggest this reaction mechanism.Other types of EDA complexes and asymmetric organic synthesis driven by EDA complexes are currently being explored in the laboratory.This dissertation is focused on the visible light-catalyzed reaction of tertiary amines with carbonyl compounds without the photosensitizers,all of the products were identified by NMR and MS,the relevant reaction yield and ee were quantitatively analyzed by gas chromatography(GC)and high-pressure liquid chromatography(HPLC).The development of other peroxydisulfate-mediated oxidative coupling reactions is currently under investigation and will be disclosed in due course.