Exploring Covalent Organic Cage as Heterogenous Platform for Aerobic Photooxidation of Alcohols

Abstract

Innovation of sustainable and efficient catalytic systems for controlled aerobic oxidation of alcohols remains a fundamental challenge in green chemistry. Here, we report a phenothiazine‐functionalized covalent organic cage ( P 2 D 3 R ) as a robust heterogeneous platform for photocatalytic dehydrogenative oxidation of primary and secondary alcohols. The trigonal‐prismatic cage was synthesized via [2 + 3] imine condensation followed by reduction. Gas‐phase DFT calculations confirmed its shape‐persistent architecture and internal confined cavity. Under ambient aerobic conditions, P 2 D 3 R catalyzes the oxidation of various benzyl alcohols to their corresponding benzaldehyde/acetophenone derivatives, under an open atmosphere without any additives or metal‐based oxidants. Optimization studies revealed rapid kinetics, high selectivity, and excellent yields under benign conditions. The catalysis demonstrates broad substrate scope for efficiently oxidizing aryl and heteroaryl alcohols bearing both electron‐donating and electron‐withdrawing substituents with high yields (>90%) and gram‐scale scalability within minutes. Moreover, the catalyst is recoverable and reusable over eight cycles without loss of catalytic activity. Notably, two value‐added natural products, vanillin and camphor, were obtained from this present catalysis, where vanillin is well known for its antibacterial and antioxidant properties. This work highlights organic cages as a promising porous material for next‐generation additive‐free photocatalysts, integrating light harvesting, substrate confinement, and recyclability within discrete multifunctional systems.