Mechanism Of Nickel- And Gold-Catalyzed Difunctionalization Of Alkenes Or Alkynes

Alkenes and alkynes are important organic molecules,and their involvement in organic synthesis is an effective method to form complex organic molecules,which is one of the very significant and challenging fields of scientific research.So far,the understanding and mastery of transition metal-catalyzed functionalization of alkenes and alkynes is far from enough and systematic understanding has not been formed,such as how chemistry and regioselectivity can be effectively regulated,coupling driving forces,catalytic properties of post-transition metals and etc.This dissertation uses chemical theory and chemical calculation,combined with theory of molecular simulation,to provide quantitative thermodynamic and kinetic data during the coupling reaction of alkene and alkyne,so as to determine the structures of reaction intermediates or transition states,clarify the mechanism of chemical bond breaking and formation,explore the optimal catalyst for the reaction,the optimal substituent on the substrate and the reaction temperature,provide valuable information and theoretical basis for the synthesis reaction of alkenes and alkynes.The main contents of this dissertation are given as follows:（1）In Chapter 3,we calculated the reaction mechanism and regioselectivity of the nickel-catalyzed trimolecular reaction of vinyl triflate,arylzinc,and alkenyl esters,focusing on revealing whether the remote difunctionalization ofγ,δ-alkenylα-cyanocarboxylate occurs through the coordination of ester groups.The calculations indicate that the ester group only coordinates to Ni during the oxidative addition step,and does not involve he contraction of six-membered nickellacycles to afford five-membered nickellacycles,which is significantly different from the previously accepted mechanism.During the oxidative addition step,the coordination of the ester group to the Ni center is crucial to avoid Heck products and achieveβ,δ-vinylarylation.The origin of the reaction’s unique regioselectivity is attributed to theβ,δ-vinylarylation pathway,which contains fewer labile high-oxidation-state Ni（III）intermediates with minimal steric hindrance in the critical oxidative addition step.Furthermore,the Ni-πandπ-πinteractions were found to reasonably explain the substituent-controlled reactivity by RDG analysis.（2）The content of Chapter 4 shows the calculation of the Au（I）-catalyzed[3+2]cyclization reaction mechanism of isoxazole and 2,1-benzisoxazole,and the analysis of the reason for the regioselectivity at the microscopic level.The results of calculation show that the N atoms of isoxazole and 2,1-benzisoxazole are both favorable for nucleophilic attack on C₂ on alkyne under the coordination of gold catalyst with alkyne,and it is a key step in determining regioselectivity.The calculation results show that the coordination of gold cation with alkyne leads to strong electrophilicity of C atom of alkyne,which is favorable for nucleophilic attack of N atom of isoxazole and 2,1-benzoxazole.Using pre-molecular orbitals revealed that the N atom of isoxazole and 2,1-benzisoxazole is more nucleophilic than that of O atom,and the electron-deficiency of C₂ on alkynes is larger than that of C₁.In addition,the different regioselective products caused by Au catalyst and Zn catalyst,respectively,are explained.