Site Selective C-H Bond Activation by a Non-Heme Oxo Iron(Ⅴ) Catalyst

Pal, Debraj (2025) Site Selective C-H Bond Activation by a Non-Heme Oxo Iron(Ⅴ) Catalyst. Masters thesis, Indian Institute of Science Education and Research Kolkata.

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Abstract

The activation of C-H & C=C bond is a recent major challenge in the field of chemistry. But in mother nature there are lots of enzyme like cyt P450, Methane monooxygenase & Rieske dioxygenase with different functionality which plays specific role by transforming the C-H bond into commercialized pdt like methane to methanol, ethane to ethanol etc. If nature can do all the things in its own way with selectively by maintaining the chirality & conformation so our goal is to mimic the active site of natural enzyme. To mimic the active site of the cyt P450 which has multiple functionality like heme containing group, synthetic earth abundant metals i.e Fe, selective oxidation of C-H bond etc-by inspiring from nature our group has already synthesize the modified bTAML system. It is a tetraanionic macrocylic biuret ligand. But the thing is that there is no chiral version of the catalyst. That is why our goal is to prepare the chiral catalyst by different way. Chirality incorporation in organic molecules is very much challenging because chiral molecules are important in pharmaceuticals, agrochemicals etc. Biomimetic synthetic catalysts have played a pivotal role in the enantioselective oxidation of C–H and C=C bonds. Enantioselective oxidation of unactivated C–H bonds remains a significant challenge in synthetic chemistry. Recent advancements have demonstrated the viability of achieving this transformation using bioinspired manganese catalysts in conjunction with hydrogen peroxide (H₂O₂) under mild conditions. These catalysts, designed to mimic the active sites of natural enzymes, facilitate the selective hydroxylation of C–H bonds, leading to the formation of chiral products with high enantioselectivity. The key to this enantioselectivity lies in the precise alignment of the substrate within the catalyst's active site. Theoretical studies suggest that a network of non-covalent interactions between the substrate and the catalyst ensures the correct orientation, allowing for selective hydrogen atom abstraction and subsequent hydroxylation. This mechanism is akin to the lock-and-key model observed in enzymatic processes, where the substrate fits into the enzyme's active site in a specific manner that dictates the reaction's outcome.

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