DFT Study On The Mechanisms Of Catalytic Alkynes Reactions Catalyzed By Copper, Silver And Palladum Complexes

In this paper, the reaction mechanism of the Cu catalyzed (E)-O-Propapargylic α,β-unsaturated Oximes rearrangement and cyclization in DMSO and MECN solvents, and Ag/Pd compounds catalyzed selective synthesis of2,3-Disubs-tituted-2H-isoindol-1-ylpho sphonate and2,3-Disubstituted-1,2-dihy droiso-quin-olin-1-yl-phosphonate in MECN solvent have been computed employing the density functional theory (B3LYP) method. In our study, we have discussed the fators that affect the catalytic activity. The factors include the type of the ligand, the number of ligand and the stereohindrance effect of the ligand. The concentration of the catalyst could also affect the catalytic activity too. All the conclusion we have obtained can afford the better idea for design more effective catalyst in transition metal catalyst system.1. DFT study on the synthesis mechanisms of the polysubstituted pyridine N-oxides by tris(triphenylphosphine)cuprousbromide.The reaction mechanisms of the Cu catalyzed (E)-O-Propapargylic α,β-unsaturated Oximes rearrangement and cyclization in DMSO and MECN solvents have been computed employing the density functional theory (B3LYP) method. Four possible pathways have been investigated. The imaginary vibrational frequency analysis of reactant, products, catalysts, all the products transition sates and intermediates is performed. The charge distribution of the species in key reaction progresses have been calculated. And the electronic densities of the bond critical points (BCP) and the ring critical points (RCP) of the key bonds are studied. The result reveals that the rate-determining reaction progress of the dominant pathway (path(IV)b) is the cyclization of intermediate MIVb4both in gas phase and in liquid(DMSO and MECN solvents) phase. Among four possible pathways, the energy barrier of the H proton shift by the solvent molecule is more lower than the way the H proton shift directly. And the effect of DMSO molecule is better than MECN molecule. Possibly due to the DMSO molecule not only can act as the bridge for the H shift, but also it can replace the PPh3ligand in catalyst. The study showed that the CuBr combine with two PPh3ligands can receive the best result than only one PPh33ligand. And if the PPh3ligand is absent, the activity of the catalyst is shut off. All the theoretical studies are coincide with the experimental result.2. DFT study on the selective synthesis of six-membered heterocycle compound2,3-Disubstituted-2H-isoindol-1-ylphosphonate and five membered heterocyclic compound2,3-Disubstituted-1,2-dihydroiso-quin-olin-1-ylphosphonate by Silver trifluoromethanesu-lfonate and Bis-(triphenylphosphine)palladium(Ⅱ) chloride.The reaction mechanisms of the AgOTf and Pd(PhCN)2Cl2catalyzed selective synthesis of2,3-Disubstituted-2H-isoindol-1-ylphosphonate and2,3-Disubstituted-1,2-dihydroiso-quinolin-1-ylphosphonate in MECN solvent have been computed employing the density functional theory (B3LYP) method. When the AgOTf act as the catalyst, three possible pathways are provided. And when the Pd(PhCN)2Cl2act as the catalyst, there are five possible pathways. The result showed that catalyst AgOTf is more suitable for the synthesis of six-membered heterocycle compound2,3-Disub-stituted-2H-isoindol-1-ylphosphonate. And the catalyst Pd(PhCN)2Cl2is more suitable for the synthesis of five-membered heterocyclic compound2,3-Disub-stituted-1,2-dihy-droiso-quinolin-1-ylphosphonate. The MECN solvent is play the salvation part in this reaction systerm, and have no impact on the result.