A DFT Study On C=X(X=N,O) Asymmetric Transfer Hydrogenation And Oxidative Borylation Catalyzed By Ru,Ir And Pd Complexes

Organic reactions catalyzed by transition metals are of great significance in the field of organic synthesis.Asymmetric synthesis reactions are essential for the synthesis of drug molecules and optically active substances.Among them,chiral amines and chiral alcohols are very important compounds in chemistry and biology,and are widely used in medicine,agrochemicals,fine chemicals,polymers,plasticizers,and other fields.In addition,alkenylboronates with C=C bonds and boron esters are an important class of organic synthesis intermediates,which can undergo various transformation reactions.It is often used in the synthesis of complex molecules and natural products,and has a very important position in the field of synthesis.Catalysts can regulate the selectivity and reaction rate of chemical reactions,improve production efficiency,reduce energy consumption and production costs,drive various chemical reactions,and make chemical synthesis simpler and more environmentally friendly.Therefore,the development of catalysts with high selectivity and activity has become a challenging task in the field of organic chemistry.In this paper,density functional theory(DFT)is used to study organic reactions such as asymmetric reactions catalyzed by transition metals like iridium,ruthenium,palladium,and oxidative boronization,and to explore the origin for high selectivity and high activity.In order to provide theoretical guidance for the development of efficient synthesis methods and the design and synthesis of high-activity corresponding catalysts.The main research contents are as follows:1.The asymmetric transfer hydrogenation reaction of allylic alcohols and secondary amines catalyzed by Ru-diamine-diphosphine complex were studied using DFT method.The reaction is carried out using a borrowing hydrogen methodology strategy.The calculated results indicate that the hydride transfer step of ketone hydrogenation reaction not only the rate-determining step,but also the chirality-determining step.The free energy barriers of the R/S path are 15.5/13.1 kcal/mol,respectively.This agrees well with experimental results.and the reaction mode conforms to the anti “lock-and-key” model in asymmetric chemistry.In order to expand the scope of catalyst application,the substrate was modulated,show that the catalyst can catalyze the hydrogenation of aliphatic ketones.2.Density functional theory(DFT)was used to study the mechanism of the diastereoselective amination of racemic alcohol with chiral tert-butylsulfonamide catalyzed by Cp*Ir complex.The calculated results show that the hydride transfer and the proton transfer are concerted synchronous process in the alcohol dehydrogenation,while stepwise process in asymmetric hydrogenation(AH)of imines to afford chiral amines product.In the whole catalytic cycle,the energy barriers for the formation of R and S configuration products are 9.3 and 19.2 kcal/mol,respectively,which is consistent with the experimental results.It was found that the diastereoselectivity of the reaction was mainly derived from the hydrogen bonding between the oxygen atom in the sulfoxide group and the nitrogen atom in the amine ligand of the catalyst.3.Density functional theory(DFT)was used to study the mechanism of the oxidative boronation of tosylhydrazone catalyzed by Pd(OAc)2.The entire catalytic cycle consists of six elementary steps.The calculated results show that the rate-determining step of the whole catalytic cycle is the transmetallation step with an energy barrier of 24.25 kcal/mol.In addition,the energy barriers of the products of the E configuration and the Z configuration are 1.76 and 4.85 kcal/mol,respectively,which is consistent with the phenomenon observed in the experiment.The energy decomposition analysis(DIA)and natural bond orbital(NBO)analysis indicated that the origin of stereoselectivity is due to the oribital interactions between the substrate and catalyst.4.Density functional theory(DFT)was used to investigate the reaction mechanism of strong alkyl C-O bond activation catalyzed by Pd(OAc)2.By calculating the possible pathways of the C-N coupling process,the most favorable pathway of the entire catalytic cycle is determined.The calculated results show that the rate-determining step is the protodepalladation step with a free energy barrier of 24.3 kcal/mol.Both anti-nucleophilic palladium and β-O elimination are more favorable than the syn-pathway,which is consistent with experimental observations.Secondly,the calculation using the substrate without the directing group explained the reason why the product could not be observed without AQ group in the experiment.Finally,the substrate is modulated in order to expand the applicability of AQ directing strategy.This strategy was found to be applicable to substrates with the leaving group in the β position.