Internuclear cyclisation. Part XXIX. Oxidation of some N-methylbiphenyl-2-carboxamides with persulphate

Authors:
  • DHD. H. Hey
    D. H. Hey
  • GJG. H. Jones
    G. H. Jones
  • MPM. J. Perkins
    M. J. Perkins
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Abstract
Oxidations of 2′-, 3′-, and 4′-methoxy-N-methylbiphenyl-2-carboxamides by potassium persulphate have been studied. Cyclisation to γ-lactams as well as the expected phenanthridinones is found to be important, particularly in alkaline solution. Similar oxidation of N-methylbiphenyl-2-carboxamide itself in alkaline solution in the presence of oxygen gives some of the γ-lactam-dienone (16) in addition to N-methylphenanthridinone. Persulphate oxidation of 3-methoxy-N-methylphenanthridinone gives the biphenanthridinone (20).