Annulation Reactions with Iron(III) Chloride: Oxidation of Imines

Article abstract of DOI:10.1021/jo00032a043

Aromatic imines react with phenylacetylene or styrene in an acetonitrile solution of iron(III) chloride to give quinolines 3 or their tetrahydro derivatives 11 together with variable amounts of products 4 arising from the reduction of the imines.The initial step appears to be a one-electron oxidation to generate iron(II) and an imine radical cation.When the reactions are carried out in the presence of stoichiometric amounts of tetrachloro-p-benzoquinone (chloranil), only quinolines 3 are obtained.