Theoretical Investigations On The Palladium-catalyzed Selective Functionalization Of 1-Chloromethyl Naphthalene And The Triphenylphosphine Catalyzed Mannich Reaction

The economic,efficient,and environmentally friendly catalytic reactions play an indispensable role in the field of chemical synthesis.In recent years,with the continuous deepening of the study of the reaction mechanism,there have a thorough understanding of the role of the catalyst in the reaction.Density functional theory is a valuable and mature technology to explore the mechanism of chemical reactions,which has the advantages of both high efficiency,high precision,and low computational cost.There are two important catalytic reaction mechanisms have been studied systematically by using density functional theory method in this thesis,one is the reaction mechanism and regioselectivity of the ligandcontrolled palladium-catalyzed 1-chloromethylnaphthalene functionalization;The other is the reaction mechanism and diastereoselectivity of the Mannich reaction catalyzed by triphenylphosphine,both of these sections are calculated by means of density functional theory.1.In the theoretical study of the reaction mechanism and regioselectivity of palladiumcatalyzed carbonylation of 1-chloromethyl naphthalene controlled by ligands,and the role of ligands-PPh Me2 and PtBu Ph2 have been investigated,respectively.The main conclusions are as follows:(1)The catalytic mechanism mainly consists substrate-catalyst complexation,oxidation addition,nucleophilic substitution and reductive elimination.(2)When the PPhMe2 was used as ligand,diphosphoryl ligand intermediates was generated in the nucleophilic substitution step.And eventually,the 2-position functionalized product is obtained will generate in the subsequent reduction and elimination steps.When the PtBu Ph2 was used as ligand,monophosphoryl ligand intermediate was generated in the nucleophilic substitution step.And eventually,the 4-position functionalized product is obtained will generate in the subsequent reduction and elimination steps.This conclusion is consistent with experimental observations.(3)When using PPh Me2 and PtBu Ph2 as ligands,the transition state energy generated by insitu functionalization is higher,indicating that the in-situ functionalized product will not be generated.This conclusion is consistent with experimental observations.2.The Manchh reaction catalyzed by PPh3 has also been theoretically studied.The reason for the diastereoselectivity of the reaction mechanism and product is discussed in depth.The calculation results show that:(1)The reaction mechanism includes: I The acetoacetate change into its enol conformation via keto-enol tautomerism catalyzed by PPh3,II The hydroxyl of the enol assists the dehydration of aniline and benzaldehyde to form the imine and another molecule of the enol;III The ?-aminocarbonyl compound is generated after the addition reaction of imine and enol.(2)The addition step of imine and enols determines the diastereoselectivity of the product.In the transitional state corresponding to the anti-diastereomers,the hydrogen bond length of N-H···O=C is shorter than which in the transitional state corresponding to the syndiastereomers,but the bond length of C-H···H-C in the transitional state corresponding to the anti-diastereomers is longer than in the transitional state corresponding to the syndiastereomers.This phenomenon shows that when the imine reacts with the enol,the NH···O=C hydrogen bonding is stronger in the transition state corresponding to the antidiastereomers and the C-H···H-C repulsion between the C-H bonds is weaker.Finally,the energy barrier of the anti-diastereomers compound(13.9 kcal/mol)is lower than the energy barrier of the syn-diastereomers(21.2 kcal/mol).This conclusion is consistent with experimental observations.