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AB initio study of Diels–Alder reactions of 1,3,4‐oxadiazole with ethylene, acrylonitrile, maleonitrile, fumaronitrile and 1,1‐dicyanoethylene. Inverse order and ratio of endo / exo reactivity
Author(s) -
Jursic Branko S.,
Zdravkovski Zoran
Publication year - 1994
Publication title -
journal of physical organic chemistry
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.325
H-Index - 66
eISSN - 1099-1395
pISSN - 0894-3230
DOI - 10.1002/poc.610071108
Subject(s) - chemistry , acrylonitrile , ab initio , oxadiazole , transition state , diels–alder reaction , reactivity (psychology) , cyclopentadiene , cycloaddition , computational chemistry , nitrile , molecular orbital , ethylene , photochemistry , organic chemistry , molecule , catalysis , medicine , polymer , alternative medicine , pathology , copolymer
Transition structures for the Diels–Alder reactions of 1,3,4‐oxadiazole with ethylene, acrylonitrile, maleonitrile, fumaronitrile, and 1,1‐dicyanoethylene were located with ab initio molecular orbital calculations with the RHF/3–21G theoretical model. The activation energies were calculated by single‐point calculations with the RHF/6–31G* and MP2/6–31G* theory levels on the RHF/3–21G geometries. Geometries of two transition structures and the corresponding reactants were generated at the MP2/6–31G* and the energies evaluated at the MP3/6–31G* level. The values obtained are comparable to those generated by MP2/6–31G*//3–21G. The asynchronicity of the transition structures follow the same trend as the corresponding all‐carbon Diels–Alder reactions with buta‐1,3‐diene and cyclopentadiene, but the activation energies are almost in opposite correlation. This behavior is explained by the oxadiazole nitrogen lone pair repulsion with the π‐orbitals of the nitrile groups.