Biologically Inspired C−H and C=C Oxidations with Hydrogen Peroxide Catalyzed by Iron Coordination Complexes

The development of catalysts for the selective oxidation of readily available hydrocarbons or organic precursors into oxygenated products is a long-standing goal in organic synthesis. In the last decade, some iron coordination complexes have shown the potential to fit this role. These catalysts can mimic the O−O activation mode of far more sophisticated iron oxygenase enzymes, generating powerful yet selective oxidants. In this review, we report state-of-the-art C−H and C=C oxidations catalyzed by non-heme iron complexes and H2O2 as the oxidant. Finally, we briefly describe some novel oxidative reactivity and the perspectives of this chemistry

Oxidation of alkane and alkene moieties with biologically inspired nonheme iron catalysts and hydrogen peroxide: from free radicals to stereoselective transformations

Abstract: The selective oxidation of hydrocarbons is a challenging reaction for synthetic chemists, but common in nature. Iron oxygenases activate the O–O bond of dioxygen to perform oxidation of alkane and alkenes moieties with outstanding levels of regio-, chemo- and stereoselectivity. Along a bioinspired approach, iron coordination complexes which mimic structural and reactivity aspects of the active sites of nonheme iron oxygenases have been explored as oxidation catalysts. This review describes the evolution of this research field, from the early attempts to reproduce the basic reactivity of nonheme iron oxygenases to the development of effective iron oxidation catalysts. The work covers exclusively nonheme iron complexes which rely on H2O2 or O2 as terminal oxidants. First, it delineates the key steps and the essential catalyst design principles required to activate the peroxide bond at nonheme iron centers without (or at least minimizing) the release of free-diffusing radicals. It follows with a critical description of the mechanistic pathways which govern the reaction between iron complexes and H2O2 to generate the oxidizing species. Eventually, the work presents a state-of-the-art report on the use of these catalysts in aliphatic C–H oxidation, olefin epoxidation and alkene syn-dihydroxylation, under substrate-limiting conditions. A special focus is given on the main strategies elaborated to tune catalyst activity and selectivity by modification of its structure. The work is concluded by a concise discussion on the essential progresses of these oxidation catalysts together with the challenges that remain still to be tackled. Graphical Abstract: [Figure not available: see fulltext.

Fe III Bipyrrolidine Phenoxide Complexes and Their Oxidized Analogues

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