DFT Study On The Mechanisms Of Several Reactions Catalyzed By Transition Metal

In present paper,the density functional method(B3LYP) is employed to study the reaction mechanism of Palladium(â…¡)-catalyzed rearrangements of propargyl acetates,and Ni and Zn-catalyzed intermolecular cyclization of aldol.The main transition states of these reactions are found out.The mechanisms of these asymmetric cyclized reactions are discussed in detail.1.Theoretical study on Palladium(â…¡)-catalyzed intermolecular rearrangements of propargyl acetatesThe mechanisms of Palladium(â…¡)-catalyzed rearrangements of propargyl acetates are investigated using density functional theory with B3LYP methods.It reveal that the coordination of the triple bond of 1 to PdCl₂(MeCN)₂ enhances the electrophilicity of alkyne,and the sunsequent nucleophilic attack of the carbonyl oxygen to the electron-deficient alkyne form ate complex IM2,whick would occurs rearrangements of acetic acid radical,the object production is produced by the reaction path of 4Ï€-electrocyclization.It is suggested that the terminal alkynal is activated by the decrease in theÏ€^*_(C1-C2) orbital energy.Throughout the reaction,all Pd¹¹ complexes obey the 18-electron-rule.2.DFT study on the mechanism of Ni and Zn-Catalyzed Aldol cyclization reationThe reaction mechanism of the Ni and Zn-catalyzed intermolecular cyclization of aldol,was studied using density functional theory(DFT) calculations at the B3LYP level.The calculations indicate that the intermolecular cyclization is the rate-determining step,and that the coordination of catalyzer and the transfer of proton are favorable.Ni as the active catalyst can decrease the energy barrier than Zn.All of the theoretical results are consistent with the experiment.