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Carbon‐supported MgO materials are excellent and sustainable catalysts for the synthesis of N‐containing heterocyclic compounds by the Friedländer condensation under mild, solvent‐free conditions. The results reported herein indicate that MgO is the most active catalytic species that accelerates the reaction compared with the catalytic behavior observed for the carbon material Norit RX3. On the basis of DFT calculations, a reaction mechanism that involves dual activation of the reacting structures by the catalyst is proposed.

We report herein for the first-time acid biomass-derived carbons from vegetal biomass, with high developed porosity, prepared through the integrating method comprising pyrolysis and surface phosphonation, able to efficiently catalyze the synthesis of quinoxalines from 1,2diamines and -hydroxi ketones, under aerobic conditions. The obtained results indicate that the type and number of acid sites drive the reaction in terms of conversion and selectivity.Furthermore, our experimental and theoretical observations suggest that the preferred reaction pathway for this transformation, in the presence of the investigated acid carbon catalysts, involves cascade reactions including imination reaction between reactants, successive imineenamine and ceto-enol tautomerisms, heterocyclization followed by dehydration, and aromatization. While the acid sites seem to be a relevant role in each reaction step, the system formed by activated carbon and molecular oxygen could be behind the last oxidative reaction to give quinoxalines.