Session: Organometallic Chemistry: Catalysis:

Activation of C–H bonds in hydrocarbons allows for the use of abundant natural compounds as starting materials. First row transition metal porphyrin complexes provide a pathway to C–H activation in hydrocarbon starting materials via homolytic cleavage of C–H bonds through a high valent oxo complex. The alkyl radical formed typically undergoes radical rebound to yield an alcohol product. Alternatively, the radical species may undergo cage escape followed by rebound at the axial ligand on the other side of the porphyrin ring. Manganese porphyrins favor the latter mechanism and therefore offer the opportunity of incorporating a variety of functional groups by C–H activation. This work aims to discover a method for manganese-catalyzed C–H amination using hydroxylamines and oximes as both the coupling partners and oxidants. Initial studies targeted the synthesis of nitroxido and oximato complexes that serve as precursors to the active oxo species. A novel oximato manganese porphyrin was prepared through protonolysis of the hydroxide complex with fluorenone oxime. Upon oxidation in the presence of a hydrocarbon substrate, the formation of an O-alkyl oximato ether was observed. This product presumably forms by a cage escape pathway, providing a foundation for investigation of the targeted C–H amination reactivity.

Professor Jamie Neely

Saint Louis University

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