Mechanistic Study of the Oxidative Coupling of Styrene with 2-Phenylpyridine Derivatives Catalyzed by Cationic Rhodium(III) via C–H Activation
摘要:
The Rh(III)-catalyzed oxidative coupling of alkenes with arenes provides a greener alternative to the classical Heck reaction for the synthesis of arene-functionalized alkenes. The present mechanistic study gives insights for the rational development of this key transformation. The catalyst resting states and the rate law of the reaction have been identified. The reaction rate is solely dependent on the catalyst and alkene concentrations, and the turnover-limiting step is the migratory insertion of the alkene into a Rh-C(aryl) bond.
Reversible Concerted Metalation–Deprotonation C–H Bond Activation by [Cp*RhCl<sub>2</sub>]<sub>2</sub>
作者:Andrew I. VanderWeide、William W. Brennessel、William D. Jones
DOI:10.1021/acs.joc.9b01716
日期:2019.10.18
The reversibility of the concerted metalation-deprotonation exchange of eight para-substituted phenyl-pyridines is examined with the parent Cp*RhCl(kappa-C,N-NC5H4-C6H4). Equilibrium constants are determined, and the free energies are used to extract the most important parameters that control the thermodynamics. K-eq values are found to correlate best with heterolytic C-H bond strengths but in a way that is not obvious considering the electrophilic nature of these activations.