title: Criteria for the elucidation of the pseudopericyclic character of the cyclization of (Z)-1,2,4,6-heptatetraene and its heterosubstituted analogues: magnetic properties and natural bond orbital analysis.
abstract: The electrocyclization of heterosubstituted derivatives of (Z)-1,2,4,6-heptatetraene, (2Z)-2,4,5-hexatrien-1-imine and (2Z)-2,4,5-hexatrienal exhibit some features which suggest a pseudopericyclic mechanism. In order to examine this, a comprehensive study including the determination of magnetic properties to estimate aromaticity and an NBO analysis throughout the reaction path was conducted. The cyclization of 5oxo-2,4-pentadienal, a process of unequivocal pseudopericyclic nature, was studied for comparison. The results suggest that, although the lone electron pair on the heteroatom in the heptatetraene derivatives seemingly plays a crucial role in the reaction mechanism, it does not suffice to deprive the reaction from the essential features of a pericyclic disrotatory electrocyclization.
authors.affiliation: Departamento de Química Física, Facultade de Química, Universidade de Santiago, 15782 Santiago de Compostela, Galicia, Spain. qftjesus@usc.es
authors.forename: Jesús
authors.initials: J
authors.lastname: Rodríguez-Otero
authors.forename: Enrique M
authors.initials: EM
authors.lastname: Cabaleiro-Lago