Mechanism And Regioselectivity Of Hydroaminoalkylation With Alkenes And Thiocarbonylation Of Alkynes

Due to the easy synthe tic methods,cheap and readily accessibility of substrates and high atomic efficiency,transition metal catalyzed C-H bond activation,hydroaminoalkylation and sulfurcarbonylation reaction have attracted the attention of chemists researchers in recent years.Computational chemistry is a powerful tool to investigate the energy of intermediates and transition state,charge density and structures.Through these information we can have a understanding on the details of the reaction mechanism of the whole catalytic cycle and even a class of catalytic reactions,the activity of the substrate and the selectivity of the reaction.The mechanistic study based on theoretical calculations helps us further develop experimental systems,including substrate expansion,better catalyst optimization,and yield improvements of the yield.In this thesis,we used computational chemistry to explore the mchanisms of zirconium catalyzed hydroaminoalkylation of olefin,palladium catalyzed thiocarbonylation of alkynes,carbon monoxide an d thiophenols.It is mainly containing two parts:1.We studied the mechanism of zirconium-catalyzted hydroaminoalkylation of olefins with silyl-benzylamines.The reaction started with C-H activation of silicyl-benzylamine catalyzed by Zr（NMe₂）₄,followed by intramolecular nucleophilic deprotonation to obtain ternary metal ring intermediates,then it occurs olefin migration insertion with ternary metal ring intermediates.Finally,proton transfer and ligand exchange between dimethylamine and inte rmediates were happened to afford aminated products and regenate the zirconium catalyst.The results showed that the proton transfer assisted by dimethylamine in catalytic cycle was more reasonable than that assited by silyl-benzylamine proposed by the pre vious study.The production ofη²-nitrogen heterocycles was the rate-determining step in this catalytic cycle.The active catalystic species was Zr（NMe₂）₄ rather than the previously proposed ring intermediateη²-azo-metal.In addition,we also analyzed the factors accounting for the regioselectivity.The calculated results suggested that the electronic effect and the steric hindrance were crucial to the regioselectivity.2.We studied the mechanism of palladium-catalyzed sulfurcarbonylation with alkynes,carbon monoxide and thiophenol prod ucingα,β-unsaturated thioester.The reaction through different mechanisms when different catalyst were applied,which originated from the structure of ligands（monodentate or bidentate ligands）.When tris（2-furan）phosphine were used,that the catalysts cycle includes exchanged the ligands of additive with tris（2-furan）phosphine,proton transfer with 5-chloro-salicylic acid（5-Cl-BSA）,1,2-migration insertion of alkyne,CO inserted into the palladium carbon bond With the Boric acid anion leaving and S-H bond activation of thiophenol.When DPEphos is used,that the catalysts cycle includes exchanged the ligands of additive with DPEphos,proton transfer with 5-chloro-salicylic acid（5-Cl-BSA）,2,1-migration insertion of alkyne,CO inserted into the palladi um carbon bond and S-H bond activation of thiophenol.These results indicated that the Pd-H species was the active catalytic species and the proton transfer with the aid of thiopheons was the rate determining step of the whole catalytic cycle,The calculated results suggested that the electronic effect and the steric hindrance were crucial to the regioselectivity.