Harnessing Solvent-3 O2 Charge Transfer Complex for Photochemical Conversion of Phosphines to Phosphine Oxides: The Synergy of Light and Ambient Air

The development of "zero-additive" synthetic protocols is the primary objective of modern green chemistry. Herein, we report a remarkably simple and robust catalyst-free and photosensitizer-free aerobic oxidation of a diverse range of tertiary phosphines to their corresponding phosphine oxides. This transformation is driven by near-UV light irradiation at room temperature, utilizing ambient air as the sole oxidant. Notably, the reaction proceeds with excellent yields in green solvent, eliminating the need for toxic transition-metal catalysts, expensive organic dyes, or hazardous solvents. This methodology circumvents the traditional kinetic barriers of oxygen activation through a solvent-3O2 charge-transfer pathway facilitated by the precise wavelength of the light source. The combination of high atom economy, the use of benign reagents, and a simplified purification process make this protocol an ideal, eco-friendly alternative for both academic and industrial applications.