Owing to their capacity to form multiple bonds concomitantly, atom transfer radical addition (ATRA) reactions represent an essential subset of radical reactions that has attracted significant attention since the 1940s. In 2018, Itoh et al. pioneered a visible-light-induced [Cu(dmp)(BINAP)](PF6)-catalyzed ATRA, enabling diversification of styrenes with carbon tetrabromide (Figure ). Leveraging the enhanced photostability of in Cu(I) complexes, conferred by the bulky ligands, which affords a kinetically stabilized excited state by impeding exciplex quenching, the authors successfully executed the difunctionalization of styrenes under mild conditions. In 2021, Reiser and Cabrera systematically examined a range of heteroleptic copper complexes incorporating dipyridylamine (dpa) alongside diverse phosphine ligands for their efficacy in photoredox catalysis. Among these, [Cu(dpa)(S-BINAP)]BF4 emerged as the most potent complex across multiple photocatalytic assays, characterized by its high excited state reduction potential (Ered = -1.39 V vs. SCE) and adequate excited state lifetime (excited state = 20.8 s). Both investigations by Itoh and Reiser demonstrated the following mechanism; (i) CBr4 undergoes a single electron reduction by an excited [Cu(I)]* complex leading to the formation Br anion and CB3 radical, (ii) the CBr3 radical subsequently adds to styrene generating a benzylic radical (9.9), (iii) 9.9 gets further oxidized by [Cu(II)] (generated in step i) to form the benzylic cation which readily reacts with Br -to afford the desired product (Figure ).