The development of metal-free catalysts has been the focus of many research efforts during the last decades, due to the increasing urge towards sustainable chemical processes. Recently, we showed the potential of pyrazine radical cations as organocatalyst for the oxidative homocoupling of primary amines using oxygen as the terminal oxidant. This was the first time that the pyrazine radical cations were selectively synthesized in high yields and successfully used as redox catalyst. Later on, we exploited the redox chemistry of N,N’-disubstituted-dihydrophenazines and used them as highly effective and selective catalyst for the oxidative homo- and heterocoupling of amines. Inspired by our previous report on the preparation of hybrid porous polymers based on polyhedral oligomeric silsesquioxane (POSS), and the aforementioned pyrazine and phenazine radical-cation oxidation catalysts, we designed and synthesized a novel type of covalently linked porous polymers exhibiting tetrakis(phenyl)silane moieties cross-linked by phenazine groups. Moreover, we extended the reaction scope of this type of catalysts for C-C bond formations via cross-dehydrogenative Aza-Henry reactions. This represents, to the best of our knowledge, the first example of a metal-free heterogeneous system for cross-dehydrogenative coupling reactions.

Persistent radical cations as metal-free catalysts for aerobic oxidative coupling reactions

ACS Spring Meeting 2021

The official archive and repository for all ACS Meetings & Expositions abstracts and select posters or presentations.