Theoretical Studies Of The Mechanism Of The Rh-Catalyzed Cyclopropanation And Decarbonylative Coupling Reaction

In recent years,transition metal Rhodium-catalyzed C-H activation for synthesis of three-membered rings or C-C activation for expansion of five-membered compounds has been widely developed,but many details of the reaction process are not clear.Therefore,elucidating the mechanism of the reaction,understanding how the reaction takes place,and their regioselectivity and diastereoselectivity will help us to understand the complex experimental results in greater depth.In this paper,the mechanism of C-H/C-C activation by transition metal Rh-catalyzed is studied by density functional theory(DFT)at the M06 level.In Chapter 3,the mechanism of Rh(?)-catalyzed cyclopropanation using N-enoxyphthalimides and alkenes is studied.Mechanisms of Rh(?)? Rh(?)and Rh(V)intermediates and their diastereoselectivity are studied.The novel Rh(V)intermediates mechanism is more favorable than Rh(?)and Rh(?)intermediates mechanisms.The distortion energy plays a key role in determining the diastereoselectivity by the distortion/interaction model analysis.In Chapter 4,the mechanism of Rh(?)-catalyzed alkyne-isatin decarbonylative coupling is studied.Our calculated results confirm that the substrate isatin is activated by C-C bond rather than C-H bond.With the assistance of the directing group,the isatin is broken with the C3-C9 bond rather than the smaller bond orders C2-C3 bond.In addition,the steric hindrance of the substituents on the directing group affects the yield of C-C activation.Especially,the substituent on the benzene ring,which directly controls chemoselectivity switching(C–C versus C–H functionalization).Through the analysis of the distortion/interaction model and frontier molecular orbitals,it is found that the interaction energy plays a key role in the regioselectivity.