Mechanistic Exploration of Cp*CoIII/RhIII-Catalyzed Carboamination/Olefination of N-Phenoxyacetamides with Alkenes.

A computational study of Cp*CoIII/RhIII-catalyzed carboamination/olefination of N-phenoxyacetamides with alkenes was carried out to elucidate the catalyst-controlled chemoselectivity. The reaction of the two catalysts shares a similar process that involves N-H and C-H activation as well as alkene insertion. Then the reaction bifurcates at the generated seven-membered metallacycle. For Cp*CoIII catalyst, the resulting metallacycle undergoes oxidation addition, reductive elimination, and protonation to yield the carboamination product exclusively. However, the Cp*RhIII catalyst could promote the subsequent olefination pathway via sequential β-H elimination, reductive elimination, oxidation addition, and protonation, which enables the experimentally observed mixtures of both carboamination and olefination products. Our results uncover that the higher propensity for the β-H-elimination of the Cp*RhIII than the Cp*CoIII catalyst in the olefination pathway could be responsible for the different selectivity and reactivity of the two catalysts.