Theoretical Study On The Regioselectivity Of Palladium-catalyzed Cumulative Diene Cyclization Reaction

In recent years,transition metal catalysis has developed into an important method and means for organic synthesis.The transition metal catalyst has the advantages of good thermal stability,high selectivity,good reliability,etc.Chemists attach great importance to this research.Today,due to the continuous depletion of the earth's resources and environmental pollution,the realization of the green conversion between the development of new catalysts and chemical reactions has always been a frontier and important field in the field of chemistry.The most important opinion is to deepen the understanding and research of the reaction mechanism and content.In this dissertation,the related reactions of the experiment are discussed in detail using the theory of quantum chemistry calculation,and the various possible reactions are searched to determine the optimal reaction path.From the energy and structure point of view,this study can provide theoretical support for the reaction and Deepen the experimental mechanism.Understanding also hopes to provide a theoretical basis for designing new related reactions.This paper mainly includes the following three aspects of work:(1)Mechanistic insight into the selective olefin-directed oxidative carbocyclization and borylation by a palladium catalyst: a theoretical study.There are totally two different reaction paths in this reaction,and density functional theory(DFT)has been carried out in two different solvents,methanol and acetic acid respectively.The calculated results show that the chemical selectivity of the reaction is controlled by the polarity of the solvent.(2)Theoretical investigation on the selectivity in the palladium-catalyzed reaction of oxidative carbonyclation-carbocyclization-carbonyclation-alkynylation of enallene.The results show that C-H activation is the rate-limiting step of the whole reaction.Coupling of Phenylacetylene(R2)with an intermediate palladium compound gives rise to other possible by-products which are energetically expelled by means of density functional theory.In addition,the charge analysis of transition states and ring tension of the other product provided the theoretical basis for the existence of the only product of the reaction.(3)Theoretical investigation of the impact of ligands on the regiodivergent Rh-catalyzed hydrothiolation of allyl amines.The study found that the source of the regional selectivity of product is due to the electronic and spatial effects of the ligands.The effect on site selectivity is illustrated by charge analysis of the transition states or the stability of corresponding intermediates.In the case of DPEphos ligand,the markovnikov addition is the major product formation reaction and the rate-determining step of the reaction is the olefin insertion and the reductive elimination,respectively.When the ligand is dppbz,anti-markovnikov addition is themain product formation reaction,the reaction rate determination step and the yield determination steps are reductive elimination.The use of density functional theory study found that the use of ligands in the experiment plays a crucial role in determining the regioselectivities.