Advances in Nickel-Metallaphotoredox Catalysis in Organic Synthesis: A New Approach to Targeted Reaction Design

Nickel-metallaphotoredox catalysis has emerged as a groundbreaking approach in organic synthesis research over the last decade. It integrates the accessibility of the redox states of inexpensive, earth-abundant nickel to capture carbon-centred radicals with the ability of photoredox catalysts (PCs) to mediate singleelectron transfer (SET) or energy transfer (ET) for efficient, selective, and sustainable transformations. Advances in catalyst design, reaction optimization, and mechanistic understanding have unlocked a wide range of cross-coupling protocols, enabling previously inaccessible or less efficient C-C bond formations. This progress opens new possibilities for innovative applications in pharmaceuticals, materials science, and beyond. This mini-review focuses on advancements in the last three years in the formation of challenging C(sp3)-C(sp3) and C(sp3)-C(sp2) bonds, both in two-component and three-component systems, featuring a broad substrate scope, with chemo-, regio-, and stereo-selectivity under mild conditions. Although mechanistic studies have been conducted for some systems, and kinetic isotope effects have been probed for others, detailed investigations using computational methods to understand the molecular interactions are lacking or sometimes fail to indicate a general trend of the catalytic mechanism. The discovery of novel approaches to open-shell radical species, which dictate reactivity and selectivity, will be of utmost importance in developing new reactions. These advances will enrich all areas of chemical sciences and create numerous opportunities for interdisciplinary research.