Metallocorrole-based Catalysts for Biomass Valorization

Epoxides are a special class of ethers with unusually high reactivity due to their ring strain. In the synthesis of a broad range of industrial products, epoxides are important synthetic intermediates. The syntheses of epoxides have been achieved with the aid of metallocorroles as catalyst. However, the challenge of catalytic bleaching and corrole solution decomposition hinders its further progress. This study presents a promising solution to the current limitations of corrole catalysts. This is proposed to be achieved by the synthesis of functionalized Mn-, Fe-, Bi-, A3 and A2B metallocorroles and the application of these metallocorroles in epoxidation of biomass-derived alkenes. These metallocorroles will further be investigated as catalysts for the synthesis of cyclic/poly carbonates from carbon dioxide and the synthesized epoxides.

In our project, a key focus was creating environmentally friendly catalysts using non-precious metals. One significant achievement was the development of a user-friendly and recyclable cobalt-corrole-derived solid composite. This composite efficiently catalyzed the hydrogenation of nitroarenes, producing valuable anilines. Interestingly, we discovered that the corrole motif's axial binding site is ideal for synthesizing heteroatom-doped catalysts. Surprisingly, a DMSO-tagged cobalt corrolate proved to be a self-contained, homogeneous hydrogenation catalyst, eliminating the need for additives. The protocol showcased its versatility by successfully synthesizing a precursor to Imatinib, a crucial anti-cancer drug for leukemia. In our pursuit of a more accessible ligand platform, we identified o-vanillin as suitable for creating augmented salen-type chelators. The resulting [NiCeL] complex served as a solution-phase precursor for a bimetallic pellet catalyst. This catalyst demonstrated remarkable tolerance to sulfur-containing substrates, known for hindering many hydrogenation processes. Notably, the catalyst could be easily removed with tweezers and reused without any loss of activity. Additionally, our research unveiled the [NiCeL] complex as a potent catalyst for electrocatalytic CO2 reduction, with a manuscript in preparation for publication. Finally, we achieved a pyrolysis-free Co-based hydrogenation protocol, relying on the in situ formation of catalytically active particles. This system successfully hydrogenated quinolines to produce valuable 1,2,3,4-tetrahydroquinolines, crucial in the pharmaceutical industry. Notably, the catalytic transformation was fully compatible with water as a solvent, emphasizing our commitment to eco-friendliness.