Strongly Reducing Visible Light Organic Photoredox Catalysts as Sustainable Alternatives to Precious Metals

摘要

Photoredox catalysis is a versatile approach for the construction of challenging covalent bonds under mild reaction conditions, commonly using photoredox catalysts (PCs) derived from precious metals. As such, there is need to develop organic analogues as sustainable replacements. Although several organic PCs have been introduced, there remains a lack of strongly reducing visible light organic PCs. Herein, we establish the critical photophysical and electrochemical characteristics of both a dihydrophenazine and a phenoxazine system that enables them success as strongly reducing visible light PCs for trifluoromethylations and dual photoredoxickel catalyzed C-N and C-S cross-couplings, reactions which have been historically exclusive to precious metal PCs.