Theoretical Study On Rhodium-catalyzed Nitrocarbamination And Sulfoxide Cycloaddition Reactions

In this work,we used density functional theory(DFT)to study the mechanisms and selectivity of the following two Rh-catalyzed systems.The purpose of our research is to use the quantum chemical method to calculate and analyze the reaction mechanisms at the molecular level,to explore the optimal mechanism of the reaction,to explain the phenomena and results of the experiment,and to reveal the nature of the experimental reactions.Two specific works are as follows:(1)Organic nitrogen compounds are important intermediates in organic synthesis,which have broad value and market prospects.For the C-N bond formation via C-H amination,nitrene precursors were found to be efficient coupling partners.To be synthetically useful,strategies that selectively aminate the C-H bond among many chemically similar ones present in organic molecules must be developed.Most of the carboamination is restricted to one-or two-component reactions.In this work,a theoretical and computational study was performed on the nitrene-participating three-component 1,4-carboamination of dienes.Through research,we found that the favorable mechanism is that under the action of the rhodium catalyst,the C-H activation occurs first,diene insertion,followed by the extrusion of CO₂ to form Rh-nitrenoid species,the 1,4-amidation product then obtained after C-N reduction elimination and protonation.Computational analysis also reveals the site-selectivity in forming the C-C bond,E/Z-selectivity and regioselectivity of carboamination.We also understand on the bonding nature of metal nitrenoid analyzed by using HOMO-LUMO interactions.(2)The second system of the thesis uses density functional theory to study the reaction mechanism.a-Carbonyl sulfoxonium ylides is considered to be a stable carbine precursor,and so it can be a coupling ligand that participates in the transition metal catalyzed activation of C-H bond.And the sulfoxonium ylides were used to be both the traceless bifunctional directing group and a carbene precursor in this work.Through experiment research,we found that the Rh-catalyzed reaction of sulfoxide ylides and different olefins may generate different cyclization products,such as[4+2]annulation products,[4+1]annulation products and non-annulation products.We put these three reactions together for theoretical study.Through the c alculation,the reasonable mechanism of the three reactions is clarified,and the influencing factors of different reactions are anal yzed.Our theoretical calculation results have also studied the reasons why different olefins are used in the experiment to obtain different products,and the reason of this phenomenon has been further studied to provide theoretical guidance for related research in the future.