Theoretical Study On The Mechanisms Of The Functionalized Reactions Of Alkenes And Amines Catalyzed By Rhodium And Copper Complexes

Heteroatomic compounds are widely found in a variety of bioactive natural products,organic materials,pesticides and drugs,and constitute by far the largest group of organic compounds.The compounds have many unique properties due to the addition of heteroatoms,which have been extensively explored by scientists.Among them,the most studied heteroatoms include nitrogen and sulfur.How to selectively construct C–N and C–S bonds is the main problem in current organic synthesis.The main research contents of this paper are as follows:（i）We use density functional theory（DFT）to explored the mechanism of hydrothiolation of1,3–dienes catalyzed by the transition metal Rhodium complex,and explain the regioselectivity of the selective addition of C–S bond.The calculation results show that whether the cationic catalyst[Rh（Josiphos）]⁺ or the electrically neutral catalyst [Rh（DPPE）Cl] catalyzes the reaction,the catalytic cycle consists of three basic steps:（1）the oxidation addition of the S and H terminals to both ends of the metal center,（2）the insertion of Rh–H into the diene,（3）the elimination of the final product by C–S reduction.Rate-determining step for the regioselectivity is Rh–H insertion,we use the ALMO-EDA method to analyze the key steps of Rh–H insertion,the results showed that the cationic catalyst/[Rh（JosiPhos）]⁺ in Rh–H insertion steps reaction,steric repulsion and orbital interaction is the key factors of regioselectivity,and dispersion effect and electrostatic interaction don’t control the regioselectivity.The results of energy decomposition analysis are verified by analyzing the repulsion between atoms within the molecule and the charge transfer between the metal center and the carbon–carbon double bond,and the results are in agreement with the results of energy decomposition.For the Rh–H insertion with electrically neutral catalyst[Rh（DPPE）Cl],the steric repulsion is the dominant factor of the regioselectivity,while the orbital interaction,electrostatic interaction and dispersion effect have little effect on the regioselectivity.The results provide a theoretical reference for the regioselectivity study of hydrothionolization reaction.（ii）Density functional theory（DFT）was used to calculate the functionalized reductive reaction of copper catalyzed amine with carbon dioxide.The calculation results show that the reaction path can be divided into four steps,respectively:（1）The ligand exchange between Cu（OH）₂ and ligand to obtain high activity Cu catalyst.（2）In the presence of high activity Cu catalyst,CO₂ is reduced by silane to aldehyde silane,（3）N-formamide derivatives are obtained by amide condensation reaction,（4）N-methylamine derivatives were obtained by reduction of N-formamide derivatives with silane.The role of cupric carbonate basic was studied in detail.Cu（OH）₂ can be reduced by silane to obtain Cu（Ⅰ）and Cu（Ⅱ）active copper catalysts,Cu CO₃ can reduce CO₂ to aldehyde intermediates（aldehyde silane）,which can be transformed to N-formamide derivatives by amide condensation reaction.The reaction mechanism of bisphosphine ligand Cu（Ⅰ）and monophosphate ligand Cu（Ⅰ）catalysts under the same reaction conditions was investigated in detail.From the perspective of kinetics,it was explained that the bisphosphine ligand Cu（Ⅰ）catalyst yielded N–methylamine derivatives,while monphosphine ligand Cu（Ⅰ）catalyst generated B25 intermediates instead of N–methylamine derivatives.In addition,the influence of copper catalysts with different oxidation states on the reaction potential energy surface was investigated,and it was found that the catalytic energy barrier of copper divalent was lower,indicating that copper divalent had higher catalytic activity.