Light in SmI2-mediated chemistry: Synthetic applications and mechanistic studies

Abstract

SmI₂ is a versatile reagent in single electron transfer-mediated reductive transformations. Photoexcitation of SmI₂ 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 SmI₂-mediated chemistry, with the potential to replace the suspected carcinogen hexamethylphosphoramide (HMPA). Rate constants of photoinduced electron transfer from SmI₂ are in the range of 10⁷–10⁹ 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 SmI₂-mediated reductive transformations.