Theoretical insights into the [4+2]/retro [4+2] cycloaddition approach to the synthesis of biaryls and polycyclic aromatics  

作　　者：LI XinYao XU JiaXi 

机构地区：[1]State Key Laboratory of Chemical Resource Engineering [2]Department of Organic Chemistry, Faculty of Science, Beijing University of Chemical Technology

出　　处：《Science China Chemistry》2013年第5期633-640,共8页中国科学（化学英文版）

基　　金：supported by the National Natural Science Foundation of China (21172017, 20972013 and 20772005);the specialized Research Fund for the Doctoral Program of Higher Education, Ministry of Education of China (20110010110011);"CHEMCLOUD COMPUTING " of Beijing University of Chemical Technology

摘　　要：A domino [4+2]/retro [4+2] cycloaddition process of cyclohexadienes with arylethynes or benzyne providing access to biaryls and polycyclic aromatics has been studied theoretically using density functional theory calculations. It has been found that the initial Diels-Alder (D-A) reaction acts as the rate-determining step and the consequent [4+2] cycloreversion reaction is feasible under the conditions used. Furthermore, the D-A reaction affects the regioselectivity, the origin of which is essentially derived from the good match of orbital coefficients between dienes and dienophiles as shown by using frontier molecular orbital (FMO) theory. Further investigation of the reactivity reveals that the reactions are predicted to fail to occur if an electron-donor group in the diene or an electron-acceptor group in the dienophile is lacking, as a consequence of the increased FMO energy gap. By further exploring the scope of substrates computationally, benzyne as an active dienophile was predicted to react with a variety of dienes in a cascade reaction under mild conditions with a low energy barrier, with the rate-determining step being the retro [4+2] cycloaddition.A domino [4 ＋ 2]/retro [4 ＋ 2] cycloaddition process of cyclohexadienes with arylethynes or benzyne providing access to biaryls and polycyclic aromatics has been studied theoretically using density functional theory calculations. It has been found that the initial Diels-Alder （D-A） reaction acts as the rate-determining step and the consequent [4 ＋ 2] cycloreversion reaction is feasible under the conditions used. Furthermore, the D-A reaction affects the regioselectivity, the origin of which is essentially derived from the good match of orbital coefficients between dienes and dienophiles as shown by using frontier molecular orbital （FMO） theory. Further investigation of the reactivity reveals that the reactions are predicted to fail to occur if an electrondonor group in the diene or an electron-acceptor group in the dienophile is lacking, as a consequence of the increased FMO energy gap. By further exploring the scope of substrates computationally, benzyne as an active dienophile was predicted to react with a variety of dienes in a cascade reaction under mild conditions with a low energy barrier, with the rate-determining step being the retro [4 ＋ 2] cycloaddition.

关 键 词：[4+2]/retro [4+2] cycloaddition BIARYLS polycyclic aromatics regioselectivity DFT study 

分 类 号：O621.3[理学—有机化学]