Synthesis of Diarylaminoacridinium Photocatalysts by Halogen-Metal Exchange Combined with Directed ortho Metalations

Photostability is an essential design aspect for the overall performance of photocatalysts, particularly as groups introduced to adjust redox properties often constitute sites of potential reactivity. Herein, we describe a modular and flexible synthetic approach to incorporate diarylamino moieties with increased photostability that allow to efficiently tune the redox behavior of a new generation of organic acridinium photocatalysts. A series of cross-coupling reactions gave access to precursors for halogen metal exchange reactions combined with directed ortho-metalations to provide reagents that allow the formation of acridinium salts with adjustable redox properties and enhanced photostability in good yields.