Catalyst-Free Aerobic Photooxidation: Mechanistic Pathways and Sustainability Perspectives

Catalyst-free aerobic photooxidation represents an increasingly important strategy for visible-light-driven oxidative synthesis using molecular oxygen as the terminal oxidant. In these transformations, substrate excitation or electron donor-acceptor (EDA) interactions directly activate O₂ through energy transfer, single-electron transfer, hydrogen-atom transfer, or EDA-mediated pathways, enabling diverse oxidative reactivity without external photocatalysts or stoichiometric oxidants. Despite rapid growth of this field, these reactions have largely been discussed as isolated transformations rather than as a unified oxidative platform governed by common photoactivation principles. This review provides a unified mechanistic and operational framework for catalyst-free aerobic photooxidation. Reported systems are organized into six major reaction classes, establishing recurring relationships between activation modes, oxygen-derived intermediates, and oxidative reactivity. The review further discusses sustainability and operational implications arising from solvent choice and reaction conditions. Together, these perspectives establish catalyst-free aerobic photooxidation as a conceptually unified platform for future sustainable oxidative synthesis.