Gas-phase generation and cyclisation reactions of imidoyl radicals

Some 1,2-diarylimidoyl radicals were generated in the gas-phase by intramolecular radical translocation from ortho-imino-aryloxyl radicals, in turn generated under flash vacuum pyrolysis (FVP) conditions. The imidoyls reacted with XR ortho'-substituents in the N-aryl group to give (in most cases) modest yields of cyclisation products. Depending on the nature of the bridging atom (X), the formation of these products was initiated either by a further hydrogen atom translocation (X = CH2), or by ipso-attack onto the aryl group (R = Ph), or by direct substitution at the heteroatom (X = S). With XR = N(Me) Ph, the major reaction product was probably the result of a competing pathway not involving the corresponding imidoyl.