title: A molecular electron density theory study of the [3 + 2] cycloaddition reaction of nitrones with ketenes.
abstract: The [3 + 2] cycloaddition (32CA) reaction between nitrones and ketenes has been studied within the Molecular Electron Density Theory (MEDT) at the Density Functional Theory (DFT) MPWB1K/6-311G(d,p) computational level. Analysis of the conceptual DFT reactivity indices allows the explanation of the reactivity, and the chemo- and regioselectivity experimentally observed. The particular mechanism of this 32CA reaction involving low electrophilic ketenes has been elucidated by using a bonding evolution theory (BET) study. It is determined that this reaction takes place in one kinetic step only but in a non-concerted manner since two stages are clearly identified. Indeed, the formation of the second C-O bond begins when the first O-C bond is already formed. This study has also been applied to predict the reactivity of nitrones with highly electrophilic ketenes. Interestingly, this study predicts a switch to a two-step mechanism due to the higher polar character of this zw-type 32CA reaction. In both cases, BET supports the non-concerted nature of the 32CA reactions between nitrones and ketenes.
authors.affiliation: Department of Organic Chemistry, University of Valencia, Dr. Moliner 50, E-46100 Burjassot, Valencia, Spain. domingo@utopia.uv.es.
authors.forename: Mar
authors.initials: M
authors.lastname: Ríos-Gutiérrez
authors.forename: Andrea
authors.initials: A
authors.lastname: Darù
authors.forename: Tomás
authors.initials: T
authors.lastname: Tejero
authors.forename: Luis R
authors.initials: LR
authors.lastname: Domingo
authors.forename: Pedro
authors.initials: P
authors.lastname: Merino