Pterin-dependent hydroxylases are a small group of enzymes that carry out the synthesis of key precursors to important metabolic transformations. An FeIVO unit is generated in the course of the enzymatic reaction, which transfers its oxygen atom to the aromatic substrates and returns to the FeII resting state. Insight into such reactions can be obtained from synthetic FeIVO complexes with an aromatic ring incorporated into the ligand framework, for which FeIII-phenolate products can be identified. However, the generation of the FeIVO unit is the rate-determining step in such studies, so mechanistic details of the hydroxylation step remain unclear. In this study, a new ligand has been designed based on the cyclam macrocycle that supports an unreactive FeIVO unit at lower temperature, but intramolecular arene hydroxylation is observed upon warming., We are thus able to monitor the arene hydroxylation process and intercept it using substrates with weak C-H bonds. Our results shed light into the relative barriers for performing arene hydroxylation and H-atom abstraction by this FeIVO unit. With the identification of this iron complex, a clearer scheme for this reaction can be drawn.

Peeking into how aromatic hydroxylation reactions are performed by synthetic FeIV(O) complexes

2019 Fall National Meeting

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