title: Selectivities of multicomponent [4 + 2]/[3 + 2] cycloadditions of 3-nitroindole with substituted alkenes: a DFT analysis.
abstract: The chemo-, regio-, and stereoselectivities of multicomponent [4 + 2]/[3 + 2] domino cycloaddition reactions involving nitroindole derivatives with vinylethers and acrylates are studied computationnally and compared to experimental results. In this process, the nitroarene first reacts as an electron-deficient heterodiene with the electron-rich alkene following an inverse electron-demand [4 + 2] process, leading to a nitronate intermediate in a fully selective way. This intermediate exclusively interacts, in a second step, with the electron-deficient alkene and undergoes a chemo- and regioselective [3 + 2] cycloaddition. The density functional theory calculations reported in this Article fully account for the selectivities observed experimentally. Electronic displacements along the reaction path are examined using a topological analysis of the electron-localization function (ELF). The first [4 + 2] reaction follows a classical concerted, although asynchronous process, which is reliably described by the frontier molecular-orbital (FMO) model. In contrast, the electronic displacements observed during the second [3 + 2] step are unexpected, involving an electron donation by the electron-deficient reaction partner.
authors.affiliation: Laboratoire de Chimie Théorique UMR 7616, UPMC Univ Paris 06, F-75005 Paris, France.
authors.forename: Hélène
authors.initials: H
authors.lastname: Gérard
authors.forename: Isabelle
authors.initials: I
authors.lastname: Chataigner
mesh_terms: D000179:Acrylates / Q000737:chemistry; D000475:Alkenes / Q000737:chemistry*; D003500:Cyclization; D007211:Indoles / Q000737:chemistry*; D008958:Models, Molecular; D008968:Molecular Conformation; D009574:Nitro Compounds / Q000737:chemistry*; D011789:Quantum Theory; D014753:Vinyl Compounds / Q000737:chemistry
chemical_list: D000179:Acrylates; D000475:Alkenes; D007211:Indoles; D009574:Nitro Compounds; D014753:Vinyl Compounds; C100195:vinyl ether; C030374:indole