Mechanistic study on the regioselectivity of Co-catalyzed hydroacylation of 1,3-dienes  

作　　者：Yuan-Ye Jiang Hai-Zhu Yu Jing Shi 

机构地区：[1]Department of Chemistry,University of Science and Technology of China [2]Department of Polymer Science and Engineering,University of Science and Technology Beijing

出　　处：《Chinese Chemical Letters》2015年第1期58-62,共5页中国化学快报（英文版）

基　　金：the NSFC(Nos.21325208,21172209,21361140372,21202006);SRFDP(No.20123402110051);FRFCU(No.WK2060190025);CAS(No.KJCX2-EW-J02);Fok Ying Tung Education Foundation,Anhui Provincial Natural Science Foundation(No.1308085QB38);China National Grid Project funded by MOE of China;the supercomputer center of Shanghai and USTC

摘　　要：Density functional theory（DFT） method was used to explore the origin of the regioselectivity of Cocatalyzed hydroacylation of 1,3-dienes.The reaction of 2-methyl-1,3-butadiene and benzaldehyde with1,3-bis（diphenylphosphino）propane ligand was chosen as the model reaction.The energies of the intermediates and transition states in the stages of oxidative cyclization,β-H elimination and C-H reductive elimination were investigated.Computational results show that β-H elimination is the ratedetermining step for the whole catalytic cycle.C1-Selective oxidative cyclization is favored over C4-selective oxidative cyclization.Besides.C4-selective oxidative cyclization is kinetically disfavored than all the steps in C1-hydroacylation mechanisms,consistent with the experimentally obtained C1-selective hydroacylation products.Analyzing the reason for such observation,we suggest that both electronic and steric effects contribute to the C1-selectivity.On the electronic aspect,C1 is more electron rich than C4 due to the methyl group on C2,which makes the electrophilic attack of aldehyde carbon on C1 more favorable.On the steric aspect,the methyl group locates farther from the ligands in the transition state of C1-selective oxidative cyclization than in that of C4-selective oxidative cyclization.Density functional theory（DFT） method was used to explore the origin of the regioselectivity of Cocatalyzed hydroacylation of 1,3-dienes.The reaction of 2-methyl-1,3-butadiene and benzaldehyde with1,3-bis（diphenylphosphino）propane ligand was chosen as the model reaction.The energies of the intermediates and transition states in the stages of oxidative cyclization,β-H elimination and C-H reductive elimination were investigated.Computational results show that β-H elimination is the ratedetermining step for the whole catalytic cycle.C1-Selective oxidative cyclization is favored over C4-selective oxidative cyclization.Besides.C4-selective oxidative cyclization is kinetically disfavored than all the steps in C1-hydroacylation mechanisms,consistent with the experimentally obtained C1-selective hydroacylation products.Analyzing the reason for such observation,we suggest that both electronic and steric effects contribute to the C1-selectivity.On the electronic aspect,C1 is more electron rich than C4 due to the methyl group on C2,which makes the electrophilic attack of aldehyde carbon on C1 more favorable.On the steric aspect,the methyl group locates farther from the ligands in the transition state of C1-selective oxidative cyclization than in that of C4-selective oxidative cyclization.

关 键 词：Density functional theory COBALT Regioselectivity HYDROACYLATION 

分 类 号：O641.1[理学—物理化学]