The C−H alkylation of arylacetamides with activated alkenes such as substituted acrylates and vinyl sulphone in the presence of a ruthenium catalyst and organic acid via the weak O-coordination under the redox free version is described. The present protocol was effective with different substituted arylacetamides including secondary and tertiary amides. The reaction mechanism including the ortho C−H bond activation, migratory insertion, and protonation by acetic acid was suggested and supported by the deuterium labeling experiments, competitive experiments, and DFT calculations including TS analysis.

A versatile and site-selective rhodium­(III)-catalyzed aerobic oxidative alkenylation of arylacetamides including primary, secondary, and tertiary amides having a weak O-coordinating acetamide directing group with alkenes is described. In the reaction, air was utilized as a sole oxidant. The reaction was compatible with activated alkenes and maleimides.

A Rh­(III)-catalyzed COOH-assisted C–H alkenylation of aromatic acids with unactivated alkenes at room temperature is described. Further, the highly challenging β-C–H olefination of acrylic acids with unactivated olefins was also demonstrated. In these reactions, ortho-alkenylated aromatic/vinylic acids were prepared in good to excellent yields. A possible reaction mechanism involving ortho C–H activation and a five-membered rhodacycle formation was proposed and supported by the deuterium-labeling studies and isolation of a key rhodacycle intermediate.

A Ru(II)-catalyzed, redox-free, two-fold aromatic/allylic C-H bond activation of aromatic acids with allylic acetates to give ( Z)-3-ylidenephthalides is described. In the reaction, H was formed as a side product. The detailed mechanistic investigation and DFT studies including the transition-state analysis support the postulate that the C-H allylation takes place at the ortho position of aromatic acids with allylic acetates followed by intramolecular cyclization at the allylic C(sp)-H via a π-allylruthenium intermediate.

An efficient Rh(III)-catalyzed aerobic oxidative C−H alkenylation of arylamides with unactivated alkenes is described. The olefination reaction was compatible with various substituted arylamides including primary, secondary, and tertiary as well as functionalized unactivated olefins. Meanwhile, ortho mono/bisalkylated arylamides were synthesized in the reaction of arylamides with norbornene. In the alkenylation reaction, molecular oxygen along with organic acid was used to regenerate the active catalyst for the next catalytic cycle. A possible reaction mechanism involving C− H activation/insertion/β-hydride elimination followed by aerobic oxidation was proposed and supported by the deuterium labeling studies.