DFT Study On Mechanism Of Several Transition Metal-Catalyzed Asymmetric Reaction

In present paper, the chiral bisoxazoline-copper(â… )-catalyzed asymmetric cyclopropanation, the rhodium(â… )-catalyzed asymmetric carbonylative [4+1] cycloaddition , the chiral zinc(â…¡)-catalyzed enantioselective alkynylation of aldehydes, and the PtCl2-catalyzed asymmetric cycloisomerization reaction of hydroxylated enynes, respectively, by means of the nonlocal density functional method (B3LYP). The mechanisms of these asymmetric reactions are discussed in detail.Density Functional Studies on Copper-Catalyzed Asymmetric Cyclopropanation of Diazoacetate with AlkeneThe chiral bisoxazoline-copper(â… )-catalyzed asymmetric cyclopropanation of diazoacetate with alkene was studied by means of the density functional theory (DFT). All the intermediates and the transition states were optimized completely at the B3LYP/6-31G level. And, to evaluate the effect of the solvent, single-point computations have been performed on the 6-31 G-optimized geometry at B3LYP/6-31G(d) level. As shown, this asymmetric cyclopropanation is exothermic. This cyclopropanation goes mainly through the formation of the catalyst-diazo methylacetate complexes, the copper(I)-carbene, the copper(I)-carbene-alkene intermediates, and the catalyst-cyclopropyl carboxylate complexes.The turnover-limiting step for the cyclopropanation is the formation of chiral catalyst-cyclopropyl carboxylate complexes. The dominant products predicted theoretically are (R,R)-cyclopropane, which is in agreement with the experiment.The Computational Study on the Mechanism of Rhodium(I)-CataIyzedAsymmetric Carbonylative [4+1] Cycloaddition with (R, R)-Me-DuPHOS-type ligand. A DFT StudyThe potential energy profile of [Rh((R,R)-Me-DuPHOS)]+-catalyzed asymmetric carbonylative [4+1] cycloaddition of vinylallenes with CO has been studied using a nonloacal density functional method (B3LYP). All the structures have been optimized completely at B3LYP/LANL2DZ level. As illustrated by computation, the intermediate 4R and 4S are the n. 4-coordination of a vinylallene and Rh catalyst. The intermediate 5R and 5S are bent o 2, n -bonded complex. The turnover-limiting step for this reaction is the carbonyl insertion reaction leading to the complexes 6. The whole enantioselective carbonylative [4+1] cycloaddition is exothermic, and the total discharged free energy is just -10.76 kJ/mol. The main product predicted theoretically is (S)-3-cyclopentenone 8S. The calculation results are in good agreement with a worth of experiment investigations.Density Functional Computations of Enantioselective Alkynylation of Aldehydes Catalyzed by Zinc(II) with a Chiral LigandThe enantioselective alkynylation of aldehydes catalyzed by chiral zinc(II)-complex was studied by means of the density functional theory (DFT). All...