Iron Complex Catalyzed Selective C-H Bond Oxidation with Broad Substrate Scope.

Area of Science:

• Catalysis
• Organic Chemistry
• Oxidation Reactions

Background:

• Selective C-H bond oxidation is crucial for synthesizing complex molecules.
• Developing efficient and selective catalysts for C-H activation remains a significant challenge in chemistry.

Purpose of the Study:

• To report a new peroxidase-mimicking iron complex, Fe-bTAML, for selective C-H bond oxidation.
• To demonstrate the catalyst's broad substrate scope and predictable selectivity based on established rules.

Main Methods:

• Utilized a biuret-modified TAML macrocyclic ligand framework complexed with iron (Fe-bTAML).
• Performed oxidation reactions on diverse substrates including arenes, heteroaromatics, and complex aliphatic compounds.
• Investigated reaction mechanisms to identify the active oxidizing species.

Main Results:

• Achieved selective oxidation of unactivated tertiary (3°) and activated secondary (2°) C-H bonds with low catalyst loading (1 mol %).
• Demonstrated excellent product yields and mass balance across 18 different substrates.
• Successfully oxidized (+)-artemisinin to (+)-10β-hydroxyartemisinin, showcasing predictable selectivity for complex molecules.
• Mechanistic studies identified Fe(V)=O as the active oxidant.

Conclusions:

• Fe-bTAML is a highly effective catalyst for selective C-H oxidation under mild, near-neutral conditions.
• The catalyst's selectivity can be predicted using steric and electronic factors, enabling targeted functionalization.
• This work provides a valuable advancement in catalytic C-H functionalization for organic synthesis.