Photocatalytic C–C Bond Coupling Reactions Towards Organic Transformation—Recent Updates

The development of sustainable and efficient methods for carbon–carbon (C–C) bond formation remains the main objective in modern organic synthesis. In recent years, photocatalysis has developed as a suitable alternative to conventional transition-metal-catalyzed approaches, offering mild reaction conditions, high functional-group tolerance, excellent atom economy, and the ability to utilize visible light as a clean and renewable energy source. Through unique radical-mediated pathways, photocatalytic strategies allow the selective activation of traditionally unreactive substrates, including haloarenes, alkanes, alcohols, carboxylic acids, and amines, thereby providing efficient routes to complex molecular architectures. Beyond organic synthesis, photocatalysis has also demonstrated significant potential in broader areas of applied chemistry. This review summarizes the major advances in photocatalytic C–C bond coupling reported from 2023 to early 2026, with special focus on C(sp3)–C(sp3), C(sp3)–C(sp2), and C(sp2)–C(sp2) bond-forming reactions. Representative catalytic systems, substrate scope, reaction mechanisms, and synthetic applications are critically discussed, including dual photoredox/transition-metal catalysis, metal-free photocatalysis, hydrogen atom transfer (HAT), proton-coupled electron transfer (PCET), radical–radical coupling, decarboxylative and deaminative functionalization, and enantioselective transformations. Finally, current challenges, emerging trends, and future opportunities for developing more sustainable, scalable, and selective photocatalytic C–C bond-forming methodologies are highlighted, providing a comprehensive resource for researchers working in synthetic and medicinal chemistry.