Robust Bio-derived Polyoxometalate Hybrid for Selective Aerobic Oxidation of Benzylic C(sp3)-H Bonds

Utilization of natural resources to construct func-tional catalytic materials for challenging organic reactions is of great importance in the chemical community, which has achieved significant attention. Herein, we describe the synthesis of a robust bio-derived polyoxometalate (POM) hybrid by the reaction of the naturally occurring phytic acid (PhyA) with MoO3, and the obtained hybrid was denoted PhyA-Mo. Systematic studies revealed that the multi-phosphate structure of PhyA enabled the synthesized PhyA-Mo to simultaneously possess a higher concentration of surface-active oxygen species and more negatively charged Mo sites, which played the role of catalytically active sites for aerobic oxidation. These two types of active sites together enabled the PhyA-Mo to show outstanding catalytic activity for aerobic oxidation of benzylic C(sp3)-H in different substrates to generate various carbonyl compounds without using any additional initiator. Importantly, the fact of realizing aerobic oxidation of benzylic C(sp3)-H bonds efficiently over POM-based materials in the absence of any radical initiator represented the main finding and the major breakthrough. Especially, this work provided a general and useful strategy to improve the catalytic performance of POM-based materials by using phosphoric acids containing multi-phosphate groups.

Automated summary

In this study, a robust bio-derived polyoxometalate (POM) hybrid, PhyA-Mo, was synthesized by reacting naturally occurring phytic acid (PhyA) with MoO3. Systematic studies revealed that the multi-phosphate structure of PhyA allowed PhyA-Mo to simultaneously possess a higher concentration of surface-active oxygen species and more negatively charged Mo sites, enabling outstanding catalytic activity for aerobic oxidation of benzylic C(sp3)-H in different substrates without using any additional initiator. Importantly, this work provided a general and useful strategy to improve the catalytic performance of POM-based materials using phosphoric acids containing multi-phosphate groups.