DFT Study on the Mechanism of Tandem Oxidative Acetoxylation/Ortho C–H Activation/Carbocyclization Catalyzed by Pd(OAc)₂

Abstract

A density functional theory (DFT) study has been conducted to unveil the mechanisms of tandem oxidative acetoxylation/ortho C−H activation/ carbocyclization catalyzed by Pd(OAc) 2 . The potential competitive reaction pathways between oxidative acetoxylation and ortho C−H activation, C−H activation with outer-sphere and inner-sphere acetate ligands, and the role of DMSO in the reaction have been discussed in detail. The calculated results indicate that the oxidative acetoxylation proceeds before ortho C−H activation in this tandem reaction in a neutral system without DMSO as a ligand coordinated to Pd. A six-membered transition state is proposed in the oxidative acetoxylation step, and a six-membered transition state is proposed in the palladium carboxylate catalyzed sp 2 C−H activation step. The coordination of outer-sphere acetate ion to Pd decreases the energy barrier of the step of ortho sp 2 C−H activation. In addition, this theoretical work demonstrates that the cosolvent DMSO as a ligand coordinated with Pd decreases the energy barrier of C−H activation. Also, the reaction tandem sequence changes to ortho C−H activation/oxidative acetoxylation/carbocyclization induced by DMSO as a ligand coordinated with Pd.

Pd-Induced Double C–H Bond Activation in Annulative Syntheses of Bipyrrole Boomerangs: Mechanistic Insights from NMR Spectroscopy and Computation

“…The potential energy surface of the reaction was explored at the PCM­(AcOH)/ωB97XD/6-31G­(d,p),Lanl2DZ level of theory, taking into account solvation effects and dispersion interactions . Similar levels of theory have recently been applied to various problems in Pd-based C–H bond activation. − Energies of the resulting stationary points were additionally evaluated using SMD­(AcOH)/M06/6-311++G­(d,p),SDD, for comparison with other recent computational work on Pd-induced reactivity. , The potential energy surface is made more complex by the conformational flexibility of the intermediates, which involves torsional degrees of freedom within the dipyrrolylmethane and around the Pd center. Intrinsic reaction coordinate (IRC) analyses performed for the bond-forming transition states and restricted conformational searches performed for local energy minima showed that the entire reaction path likely involves conformational rearrangement of intermediates at several stages.…”

Theoretical Design of a Catalyst with Both High Activity and Selectivity in C–H Borylation

“…In accordance with previous computational studies on borylation reactions catalyzed by transition-metal complexes, − all calculations were carried out by the DFT method with the ωB97X-D method using the Gaussian 09 program . In the geometry optimization, the SDD basis set is used for the Ir center and 6-311G­(d,p) , basis sets are used for all of the other atoms .…”

pH-Dependent transfer hydrogenation or dihydrogen release catalyzed by a [(η6-arene)RuCl(κ2-N,N-dmobpy)]+ complex: a DFT mechanistic understanding

“…In accordance with our previous computational studies, 3,19,[50][51][52][53][54][55] all calculations in this study were carried out using the DFT method with uB97X-D 56 using the Gaussian 09 program. 57 The SMD polarizable continuum model in water as the solvent was employed in the calculations.…”