title: Spin-coupled study of the electronic mechanism of the hetero-Diels-Alder reaction of acrolein and ethene.
abstract: Modern valence bond theory, in its spin coupled form, is used to elucidate the electronic rearrangements that take place during the course of the gas-phase hetero-Diels-Alder cycloaddition reaction of s-cis-acrolein (cis-1-oxabutadiene or cis-propeneal) and ethene. It is found that the most dramatic changes to the electronic structure occur in a relatively narrow interval of the reaction pathway soon after the transition state and that the system passes through a geometry at which it can be considered to be significantly aromatic. Although concerted, the reaction is markedly asynchronous, with the breaking of the carbon-oxygen pi bond, and the formation of the new carbon-oxygen sigma bond, "lagging behind" somewhat the other bond-making and bond-breaking processes.
authors.affiliation: Department of Chemistry, University of York, Heslington, York, YO10 5DD, UK.
authors.forename: Joshua J
authors.initials: JJ
authors.lastname: Blavins
authors.forename: David L
authors.initials: DL
authors.lastname: Cooper
authors.forename: Peter B
authors.initials: PB
authors.lastname: Karadakov