Non‐Chelate‐Assisted Palladium‐Catalyzed Aerobic Oxidative Heck Reaction of Fluorobenzenes and Other Arenes: When Does the C−H Activation Need Help?

The pyridone fragment in the ligand [2, 2’-bipyridin]-6(1H)-one (bipy-6-OH) enables oxidative Heck reaction of simple arenes with oxygen as sole oxidant and no redox mediator. Arenes either electron-donating or electron-withdrawing groups can be functionalized this way. Experimental data on toluene model arene shows that C−H activation step is turnover limiting structure crucial to facilitate reaction, which supports involvement step. In case fluoroarenes, alkenylation mono 1,2-difluoro benzenes requires presence bipy-6-OH. contrast, detrimental for 1,3-difluoro, tri, tetra pentafluoro carried out using just [Pd(OAc)2]. This correlates acidity most acidic undergoing easier so other steps such coordination-insertion olefin become kinetically important polyfluorinated arenes. use a catalytic amount sodium molybdate base proved optimal all these reactions.