Unconventional mechanism and selectivity of the Pd-catalyzed C-H bond lactonization in aromatic carboxylic acid

Chlorobenzene-driven palladium-catalysed lactonisation of benzoic acids

Herein, we developed a palladium-catalysed C-H cyclisation of benzoic acids in chlorobenzene without additional oxidants. The key to the success of these reactions is the use of chlorobenzene, which serves a dual role as a solvent and an oxidant, thus providing a simple and efficient method for synthesising phthalides.

Mechanistic Details of the Pd-catalyzed and MPAA Ligand-Enabled β-C(sp3 )-H Acetoxylation of Free Carboxylic Acid

Transition metal-catalyzed C-H bond oxidation of free carboxylic acid stands as an economic, selective, and efficient strategy to generate lactones, hydroxylated products, and acetoxylated products and attracts much of the chemists' attention. Herein, we performed a density functional theory study on the mechanism and selectivity in Pd-catalyzed and MPAA ligand-enabled C-H bond acetoxylation reaction. It was found that the ligand, base, and substrate are important in determining the reaction mechanism and the selectivity. The acetic anhydride additive is critical in leading the reaction to be acetoxylation, instead of the lactonization, through a facile σ-bond metathesis mechanism that leads to the Pd-OAc in-termediate. Our study sheds light on the further development of transition metal-catalyzed C-H bond oxidation reactions.

Nucleophilic aromatic substitution of non-activated aryl fluorides with aliphatic amides

Nucleophilic aromatic substitution (S_NAr) reactions of non-activated aryl fluorides with amide enolates are reported. The reaction proceeds under relatively mild reaction conditions. Lactams also participate in the reaction to give 2-arylated lactams. DFT calculations suggest that the reaction proceeds through a concerted S_NAr pathway.