Quinoline nitroxide radicals.Ipso-attack in the reaction between 2-methoxy and 2-cyanoquinolineN-oxide, and phenylmagnesium bromide

2-Methoxy and 2-cyanoquinoline N-oxide, when treated with phenylmagnesium bromide, undergo a nucleophilic ipso-attack at C-2, yielding, by elimination of methoxymagnesium bromide or cyanomagnesium bromide, the corresponding 2-phenylquinoline N-oxides, which react with the excess of Grignard reagents forming 2,2-diphenylquinoline 1-oxyls. Even when the methoxy and cyano groups are in position 4, the attack by the Grignard reagent takes place at C-2 giving 2-phenylquinolines and 2-phenylquinoline N-oxides by elimination of hydroxymagnesium bromide and bromomagnesium hydride, respectively; the formation of 2,2-diphenylquinoline l-oxyls in these reactions is discussed.