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High valent iron-oxo intermediates play key role in enzymatic oxidations. For example, in the cytochrome P450 family of enzymes, the high-valent FeIV(O)(porphyrinradical-cation), isoelectronic with FeV(O), has been shown to be the reactive intermediate in the selective hydroxylation of camphor. In Rieske dioxygenases, FeV(O) has been proposed as the reactive intermediate for the oxidation of aliphatic C-H bonds. We have successfully synthesized an FeV(O) complex of a biuret-containing Fe-complex (Fe-bTAML) which shows remarkable stability at room temperature. This higher stability has allowed us to study oxidation reactions of FeV(O) with unactivated alkanes at room temperature using a variety of physical and spectroscopic techniques. This mechanistic understanding has helped us to develop synthetic methodologies in which Fe-bTAML was used as a catalyst to perform selective oxidation of unactivated 3° and activated 2° C-H bonds with unprecedented regioselectivity, expanded substrate scope, high stereoretention, and very low catalyst loadings (1 mol %) using mCPBA as the oxidant. Aliphatic C-H oxidation at 3° and 2° sites of complex substrates were oxidized with predictable selectivity using steric, electronic and stereoelectronic rules, which also included oxidation of the anti-malarial drug (+)-artimisinin to (+)-10β-hydroxyartimisinin. |