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A computational investigation on the sequential rearrangement mechanism of 2‐allyl‐2,4,5‐hexatrienaldehyde involving [1,5]‐hydrogen migration and 8π‐electrocyclization
Author(s) -
Zhu Yuanqiang,
Guo Yong,
Zhang Lidong,
Xie Daiqian
Publication year - 2007
Publication title -
journal of computational chemistry
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.907
H-Index - 188
eISSN - 1096-987X
pISSN - 0192-8651
DOI - 10.1002/jcc.20714
Subject(s) - isomerization , chemistry , complete active space , computational chemistry , exothermic reaction , density functional theory , cycloaddition , reaction mechanism , cope rearrangement , perturbation theory (quantum mechanics) , stereochemistry , physics , basis set , quantum mechanics , organic chemistry , catalysis
Abstract The sequential rearrangement reaction mechanism of the 2‐allyl‐2,4,5‐hexatrienaldehyde has been studied at the unrestricted Becke three‐parameter hybrid functional combined with Lee–Yang–Parr correlation functional (UB3LYP)/6‐31G**, Complete Active Space Self‐Consistent Field (CAS (8,8))/6‐31G**, Configuration Interaction with Single and Double Excitations (CISD)//UB3LYP/6‐31G** and the second‐order perturbation theory based on the CASSCF reference wave function (CASPT2)//CAS(8,8)/6‐31G** levels. Two pathways have been found to be involved for this reaction. The first pathway includes four processes of the rotation of the C3C4 single bond, the stepwise [2 + 2] cycloaddition, the [1,5]‐hydrogen migration, and the ring opening isomerization, while the second pathway undergoes only two processes of the [1,5]‐hydrogen migration and the 8π‐electrocyclization. The calculation results indicate that the second pathway is favorable, in good agreement with the recent experimental observation. The whole reaction is stepwise and strong exothermic. © 2007 Wiley Periodicals, Inc. J Comput Chem, 2007