Mechanistic Insights into the Ni-Catalyzed Reductive Carboxylation of C-O Bonds in Aromatic Esters with CO : Understanding Remarkable Ligand and Traceless-Directing-Group Effects.

The mechanism of the Ni -catalyzed reductive carboxylation reaction of C(sp )-O and C(sp )-O bonds in aromatic esters with CO to access valuable carboxylic acids was comprehensively studied by using DFT calculations. Computational results revealed that this transformation was composed of several key steps: C-O bond cleavage, reductive elimination, and/or CO insertion. Of these steps, C-O bond cleavage was found to be rate-determining, and it occurred through either oxidative addition to form a Ni intermediate, or a radical pathway that involved a bimetallic species to generate two Ni species through homolytic dissociation of the C-O bond.

A theoretical study on the oxidation of alkenes to aldehydes catalyzed by ruthenium porphyrins using O as the sole oxidant.

Density functional theory (DFT) calculations were used to study the ruthenium porphyrin-catalyzed oxidation of styrene to generate an aldehyde. The results indicate that two reactive oxidants, dioxoruthenium and monooxoruthenium-superoxo porphyrins, participate in the catalytic oxidation. In the mechanism, the resultant monooxoruthenium porphyrin acts in the tandem epoxide isomerization (E-I) to selectively yield an aldehyde and generate a dioxoruthenium porphyrin, thereby triggering new oxidation reaction cycles.