Light in SmI 2 ‐mediated chemistry: Synthetic applications and mechanistic studies

SmI 2 is a versatile reagent in single electron transfer‐mediated reductive transformations. Photoexcitation of SmI 2 generates a reactive excited state capable of transferring an electron to substrates that are recalcitrant towards accepting electrons. Synthetic results unequivocally indicate light as a green and sustainable promoter of SmI 2 ‐mediated chemistry, with the potential to replace the suspected carcinogen hexamethylphosphoramide (HMPA). Rate constants of photoinduced electron transfer from SmI 2 are in the range of 10 7 –10 9 M −1 s −1 , which are an order of magnitude higher in comparison with the ground state process. Recent advancement in Eu II ‐ and Ce III ‐based photo‐redox catalysis rejuvenated the area of photo‐catalyzed reactions of low‐valent lanthanides. This review article aims to illustrate the role of photoexcitation on SmI 2 ‐mediated reductive transformations.