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The Mechanism of Rhodium Catalyzed Allylic C–H Amination

preprint
submitted on 01.09.2019 and posted on 04.09.2019 by Robert Harris, Jiyong Park, Taylor Nelson, Nafees Iqbal, Daniel Salgueiro, John Bacsa, Cora MacBeth, Mu-Hyun Baik, Simon Blakey
The mechanism of catalytic allylic C–H amination reactions promoted by Cp*Rh complexes is reported. Reaction kinetics experiments, stoichiometric studies, and DFT calculations demonstrate that allylic C–H activation to generate a Cp*Rh(π-allyl) complex is viable under mild reaction conditions. The role of external oxidant in the catalytic cycle is elucidated. Quantum mechanical calculations, stoichiometric reactions, and cyclic voltammetryexperiments support an oxidatively induced reductive elimination process of the allyl fragment with an acetate ligand. Lastly, evidences supporting the amination of an allylic acetate intermediate is presented. Both nucleophilic substitution catalyzed by Ag+that behaves as a Lewis acid catalyst and an inner-sphere amination catalyzed by Cp*Rh are shown to be viable for the last step of the allylic amination reaction.

Funding

NSF Center for C-H Functionalization CHE-1700982

History

Email Address of Submitting Author

sblakey@emory.edu

Institution

Emory University

Country

USA

ORCID For Submitting Author

0000-0002-4100-8610

Declaration of Conflict of Interest

No conflict of interest

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