Integration of cavitand with biologically inspired manganese oxidation catalyst for C-H oxidation reactions Siu-Chung Chan, Ricard López, Agustí Lledó, Miquel Costas Universitat de Girona, Spain Direct functionalization of unactivated sp 3 C–H bonds represents a powerful synthetic tool to construct and diversify molecules.However, primary C–H bonds of unfunctionalized alkyl chains are highly unreactive due to their high bond dissociation energy (BDE > 100 kcalmol -1 ), and their catalytic oxidation remains also as an insurmountable challenge for non-enzymatic molecular catalysts. Herein, we present an innovative supramolecular approach that can oxidize primary C–H sites by integrating a cavitand ( CAVCO2H ) containing carboxylic acid at their upper rim of the aromatic walls with biologically inspired oxidation manganese catalysts containing tetradentate aminopyridine N4 ligand (scheme 1). The derivatized cavitands can thus synergistically engage with the metal complex in the H 2 O 2 activation process generating the reactive Mn V =O( CAVCO2 ) under catalytic regime (scheme 1), rendering the oxidant in close proximity to the cavity for hosting the substrates. Under catalytic condition, the confinement of the preorganized short and small size of alkanes within the cavity of the cavitand assists the oxidation of their primary C–H sites and results in the formation of the corresponding terminal epoxides. This represents a cooperative catalytic approach by taking the advantages of the strong oxidation power of the biologically inspired oxidation catalyst 1 and the ability to bind non-polar substrates by means of hydrophobic force of the cavitand 2 .
Scheme 1 . Supramolecular approach by integration of reactive oxidation catalysts and carboxylic acid functionalized cavitand ( CAVCO2H ) for unprecedented primary C–H oxidation of alkanes in this work. References 1. Vicens, L.; Olivo, G.; Costas, M. ACS Catal. 2020, 10, 8611.Yu, Y.; Rebek Jr, J. Acc. Chem. Res. 2018, 51, 3031.
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