Intra- vs inter-molecular electron transfer processes in CN bond forming reactions. Photochemical, photophysical and theoretical study of 2′-halo-[1,1′-biphenyl]-2-amines

Abstract N -Arylation reaction is obtained when 2′-halo-[1,1′-biphenyl]-2-amines are irradiated in basic medium. On the basis of photochemical, photophysical experiments and computational studies we propose that carbazolesare formed by intermolecular electron transfer via S RN 1 mechanism. In general, biphenylamines with an EDG like Me or OMe behave in the same way as H giving both, cyclized and reduced products. On the other hand, biphenylamines containing EWG like CN, COOEt or CF 3 gave only the corresponding carbazole. Herein, we report for the first time the chain length for the propagation cycle of intramolecular S RN 1 reactions and explain that differences in the distribution of products suggest differences regarding the overall mechanism involved.