Palladium-Catalyzed Direct Alkenylation Of C-H Bonds Under O₂ Atomosphere

Recently,the cross-dehydrogenative-coupling between two C-H bonds for constructing C-C bonds has become one of the most active areas of research and extensive progress has been made in all aspects of such reactions.However,in most palladium-catalyzed cross-dehydrogenative-coupling,stoichiometric oxidants are required to regenerate activate Pd? catalyst.The use of molecular oxygen as the terminal oxidant or as the only oxidant has appeared as an ideal choice with the production of a minimum amount of waste.Nevertheless,despite the several recent discoveries,aerobic cross-dehydrogenative-coupling is still in its infancy.In the future,the construction C-C bonds via dehydrogenation coupling reaction using oxygen as sole oxidant or terminal oxidant is expected to play an important role in organic synthesis.In the presence of catalytic system of Pd(OAc)2/PivOH/DL-pGu-OH,polyfluoroarenes can react with alkenes via cross-dehydrogenative-coupling.The reaction made use of molecular O2 as the sole oxidant and worked in only 1 atm.of O2.We also found that Pd(OAc)2/PivOH/DL-pGu-OH showed high catalytic activity for direct arylation between polyfluoroarenes and simple arenesPd(OAc)2-catalyzed aerobic direct olefination of caffeine has been developed Molecular oxygen was used as the sole oxidant for this kind of transformation.The Z-Phe-OH plays important roles in the reaction efficiency.This reaction also worked under 1 atm.of O2.