Metal-free photocatalytic C(sp3)–H bond activation

Visible-light-induced cascade reaction: a sustainable approach towards molecular complexity

Photoredox catalysis has demonstrated rapid evolution in the field of synthetic organic chemistry. On the other hand, the splendour of cascade reactions in providing complex molecular architectures renders them a cutting-edge research area. Therefore, the merging of photocatalysis with cascade synthesis brings out a synthetic paradigm with immense potential. The development of photocascade catalysis for a target molecule with a particular molecular skeleton and stereochemical framework presents certain challenges but provides a robust and environmentally benign synthetic alternative. This comprehensive review assembles all the accomplishments and highlights of visible-light-induced cascade reactions with literature coverage up to October 2022.

Visible light-induced functionalization of indazole and pyrazole: a recent update

Indazole and pyrazole are renowned as a prodigious class of heterocycles having versatile uses in medicinal as well as industrial chemistry. Considering sustainable approaches, recently, photocatalysis has become an indispensable tool in organic chemistry due to its application for the activation of small molecules and the use of a clean energy source. In this review, we have highlighted the use of metal-based photocatalysts, organic photoredox catalysts, energy transfer photocatalysts and electron-donor-acceptor complexes in the functionalization of indazole and pyrazole. This perspective is arranged based on the types of functionalization reactions on indazole and pyrazole. A detailed discussion regarding the reaction mechanism of each reaction is given to provide a comprehensive guide to the reader. Finally, a summary of existing challenges and the future outlook towards the development of efficient photocatalytic methods for functionalization of these heterocycles is also presented.