• myGriffith
    • Staff portal
    • Contact Us⌄
      • Future student enquiries 1800 677 728
      • Current student enquiries 1800 154 055
      • International enquiries +61 7 3735 6425
      • General enquiries 07 3735 7111
      • Online enquiries
      • Staff phonebook
    View Item 
    •   Home
    • Griffith Research Online
    • Journal articles
    • View Item
    • Home
    • Griffith Research Online
    • Journal articles
    • View Item
    JavaScript is disabled for your browser. Some features of this site may not work without it.

    Browse

  • All of Griffith Research Online
    • Communities & Collections
    • Authors
    • By Issue Date
    • Titles
  • This Collection
    • Authors
    • By Issue Date
    • Titles
  • Statistics

  • Most Popular Items
  • Statistics by Country
  • Most Popular Authors
  • Support

  • Contact us
  • FAQs
  • Admin login

  • Login
  • Formation of an Unusual Four-Membered Nitrogen Ring (Tetrazetidine) Radical Cation

    Thumbnail
    View/Open
    81414_1.pdf (589.3Kb)
    Author(s)
    Camp, David
    Campitelli, Marc
    Hanson, Graeme R
    Jenkins, Ian D
    Griffith University Author(s)
    Jenkins, Ian D.
    Camp, David B.
    Campitelli, Marc R.
    Year published
    2012
    Metadata
    Show full item record
    Abstract
    Treatment of triphenylphosphine (Ph3P) with an excess of diisopropyl azodicarboxylate at 0-25 àresulted in the formation of a symmetrical tetraalkyl tetrazetidinetetracarboxylate radical cation, containing the elusive cyclic N4 ring system. Electron paramagnetic resonance (EPR) spectroscopy revealed a 9-line spectrum, with hyperfine coupling constants indicative of four almost magnetically equivalent nitrogen atoms. The radical species was surprisingly long-lived, and could still be observed several hours after generation and standing at 25 î Expansion of the central resonance revealed further splitting into a pentet ...
    View more >
    Treatment of triphenylphosphine (Ph3P) with an excess of diisopropyl azodicarboxylate at 0-25 àresulted in the formation of a symmetrical tetraalkyl tetrazetidinetetracarboxylate radical cation, containing the elusive cyclic N4 ring system. Electron paramagnetic resonance (EPR) spectroscopy revealed a 9-line spectrum, with hyperfine coupling constants indicative of four almost magnetically equivalent nitrogen atoms. The radical species was surprisingly long-lived, and could still be observed several hours after generation and standing at 25 î Expansion of the central resonance revealed further splitting into a pentet (hyperfine coupling to the four methine protons). Three mechanistically plausible structures containing the tetrazetidine substructure were proposed based on the 9-line EPR spectrum. Following DFT calculations, the predicted hyperfine coupling constants were used to simulate the EPR spectra for the three candidate structures. The combined calculations and simulations were consistent with a radical cation species, but not a radical anion or radical carbenoid structure. The lowest energy conformation of the N4 ring was slightly puckered, with the alkyl carboxylate groups all trans and the four carbonyl groups aligned in a pinwheel arrangement around the ring. Analogous results were obtained with the original Mitsunobu reagents, Ph3P and diethyl azodicarboxylate, but not with Ph3P and di-tert-butyl azodicarboxylate. A mechanism is proposed based on a radical version of the Rauhut-Currier or Morita-Baylis-Hillman reactions.
    View less >
    Journal Title
    Journal of the American Chemical Society
    Volume
    134
    Issue
    39
    DOI
    https://doi.org/10.1021/ja303019y
    Copyright Statement
    This document is the Accepted Manuscript version of a Published Work that appeared in final form in Journal of the American Chemical Society, copyright 2012 American Chemical Society after peer review and technical editing by the publisher. To access the final edited and published work see dx.doi.org/10.1021/ja303019y.
    Subject
    Physical Organic Chemistry
    Chemical Sciences
    Publication URI
    http://hdl.handle.net/10072/48690
    Collection
    • Journal articles

    Footer

    Disclaimer

    • Privacy policy
    • Copyright matters
    • CRICOS Provider - 00233E

    Tagline

    • Gold Coast
    • Logan
    • Brisbane - Queensland, Australia
    First Peoples of Australia
    • Aboriginal
    • Torres Strait Islander