RhI/RhIII catalyst-controlled divergent aryl/heteroaryl C-H bond functionalization of picolinamides with alkynes
The ability to establish switchable site-selectivity through catalyst control in the direct functionalization of molecules that contain distinct C-H bonds remains a demanding challenge that would enable the construction of diverse scaffolds from the same starting materials. Herein we describe the realization of this goal, namely a divergent heteroaryl/aryl C-H functionalization of aromatic picolinamide derivatives, targeting two distinct C-H sites, either at the pyridine ring or at the arene unit, to afford isoquinoline or ortho-olefinated benzylamine (or phenethylamine) derivatives. This complementary reactivity has been achieved on the basis of a RhIII/RhI switch in the catalyst, resulting in different mechanistic outcomes. Notably, a series of experimental and DFT mechanistic studies revealed important insights about the mechanism of the reaction and reasons behind the divergent regiochemical outcome ; We thank the Spanish Government (MINECO, CTQ2012-35790) for financial support. N. R. thanks the MICINN for a Ramón y Cajal contract and the European Commission for a Marie Curie Career Integration Grant (CIG: CHAAS-304085). We also thank the Centro de Computación Científica de la UAM for their generous allocation of computer time
