functionalization and C-S bond formation of thiobenzanilides 54, employing inexpensive graphitic carbon nitride g-C3N4 15 as a photocatalyst under ambient air and blue LED irradiation (Scheme 17) . This method is gram-scalable, operates at room temperature, and tolerates a wide range of functional groups, including nitro substituents. Moreover, it eliminates the need for strong bases or organic oxidants. Notably, the photocatalyst g-C3N4 15 exhibited excellent stability and reusability, maintaining efficiency for at least five cycles. The proposed mechanism begins with the adsorption of N-substituted benzothioamide 54 (R 1 =H, R 2 =Ph) onto the surface of g-C3N4 15, forming a complex A. This adsorption creates a new donor energy level above the valence band of g-C3N4 15. Upon visiblelight irradiation, an electron is promoted from the donor level of complex A to the conduction band of g-C3N4 15, resulting in the formation of a radical cation B. Subsequent quenching of the photogenerated electron by molecular oxygen (O₂) and deprotonation of B leads to the formation of a sulfur-centered radical C. This radical C then undergoes intramolecular cyclization, attacking the aromatic ring to form an aryl radical intermediate D. Further interaction of D with the conduction band of g-C3N4 15 generates a cationic species E. Finally, deprotonation and rearomatization of E yield the desired benzothiazole 53 (R 1 =H, R 2 =Ph). In this reaction, molecular oxygen (O₂) functions as an electron scavenger, being reduced to superoxide radicals (O₂ •-), which can further react with protons to form hydroperoxyl radicals (HOO • ). These intermediates ultimately convert into hydrogen peroxide (H₂O₂) and regenerate molecular oxygen, sustaining the catalytic cycle. This environmentally friendly, metal-free protocol underscores the utility of g-C3N4 15 as a robust photocatalyst for sustainable organic transformations.