Get access

Template Synthesis of Benzannulated N-Heterocyclic Carbene Ligands

Authors

  • F. Ekkehardt Hahn Prof. Dr.,

    1. Institut für Anorganische und Analytische Chemie Westfälische Wilhelms-Universität Münster Wilhelm-Klemm-Strasse 8, 48149 Münster, Germany, Fax: (+49) 251-8333108
    Search for more papers by this author
  • Volker Langenhahn Dr.,

    1. Institut für Anorganische und Analytische Chemie Westfälische Wilhelms-Universität Münster Wilhelm-Klemm-Strasse 8, 48149 Münster, Germany, Fax: (+49) 251-8333108
    Search for more papers by this author
  • Nicole Meier Dipl.-Chem.,

    1. Institut für Anorganische und Analytische Chemie Westfälische Wilhelms-Universität Münster Wilhelm-Klemm-Strasse 8, 48149 Münster, Germany, Fax: (+49) 251-8333108
    Search for more papers by this author
  • Thomas Lügger Dr.,

    1. Institut für Anorganische und Analytische Chemie Westfälische Wilhelms-Universität Münster Wilhelm-Klemm-Strasse 8, 48149 Münster, Germany, Fax: (+49) 251-8333108
    Search for more papers by this author
  • Wolf Peter Fehlhammer Prof. Dr.

    1. Deutsches Museum, Museumsinsel 1 80306 München, Germany
    Search for more papers by this author

Abstract

The reaction of 2-azidophenyl isocyanide (7) with [M(CO)5(thf)] (M=Cr, W) yields the isocyanide complexes [M(CO)5(7)] (M=Cr 8, M=W 9). Complexes 8 and 9 react with tertiary phosphines such as triphenylphosphane at the azido function of the isocyanide ligand to give the 2-triphenylphosphiniminophenyl isocyanide complexes 10 (M=Cr) and 11 (M=W). The polar triphenylphosphiniminophenyl function in complexes 10 and 11 can be hydrolyzed with H2O/HBr to afford triphenylphosphane oxide and the complexes containing the unstable 2-aminophenyl isocyanide ligand. This ligand spontaneously cyclizes by intramolecular nucleophilic attack of the primary amine at the isocyanide carbon atom to yield the 2,3-dihydro-1H-benzimidazol-2-ylidene complexes 12 (M=Cr) and 13 (M=W). Double deprotonation of the cyclic NH,NH-carbene ligands in 12 and 13 with KOtBu and reaction with two equivalents of allyl bromide yields the N,N′-dialkylated benzannulated N-heterocyclic carbene complexes 14 (M=Cr) and 15 (M=W). The molecular structures of complexes 9 and 1115 were confirmed by X-ray diffraction studies.

Ancillary