Substituent effects on stoichiometric and catalytic cleavage of carbon-nitrogen bonds in aniline derivatives by ruthenium-phosphine complexes

The reactivity of various o-acylaniline derivatives with ruthenium complexes was examined. The reaction of o-acylanilines with RuH ₂(CO)(PPh₃)₃ (1) or an activated ruthenium species formulated as "Ru(CO)(PPh₃)₃" (4) gave amido hydrido complexes 3 and aryl amido complexes 6 formed via N-H and C-N bond cleavage, respectively. Addition of olefins, such as vinylsilanes, accelerates the C-N bond cleavage. The aryl amido complexes 6 can provide the C-N arylation product upon treatment with arylboronates. The relative reactivity of o-acylanilines bearing various substituents was investigated by competition experiments, and it was found that electron-donating substituents increase the relative facileness of the C-N bond cleavage in both stoichiometric and catalytic reactions. The trend observed here is different from the one observed for the previously reported tantalum-mediated C-N bond cleavage.