The Palladium/norbornene catalytic system: novel synthetic applications and mechanistic insights

Novel synthetic applications of the Palladium/norbornene catalytic system are presented herein. Selective aromatic and aliphatic (or heteroaromatic) C-H bond activation in sequence allowed to present two new methods featuring intramolecular C-C bond formation. Development of one of this method employing alpha nitro esters allowed to find a novel method for the synthesys of aryl nitriles in the absence of a cyanide source. DFT calculations on this unsual reactivity proposes that the reaction occours through a Pd-mediated retro Mannich reaction. Mechanistic study on Pd/norbornene catalyzed sequences by DFT calculations allowed to enlight the role of substituents on the reacting aryl halides, which triggers the formation of Pd(IV) complexes responsible for selective biaryl synthesis.