Phenothiazines, Dihydrophenazines, and Phenoxazines: Sustainable Alternatives to Precious-Metal-Based Photoredox Catalysts.

The application of photoredox catalysis to atom-transfer radical polymerization (ATRP) has resulted in the development of strongly reducing organic photoredox catalysts (PCs) that are some of the most reducing catalysts known. The objectives of this review are to highlight these PCs with regard to their development and applications in polymer and organic synthesis, as well illuminate aspects of these PCs that remain to be studied further.