Chemodivergence made possible by micellar photocatalysis: C-H arylation vs. N-dealkylation of chlorinated benzamides in aqueous media

Abstract

Micellar photocatalysis has recently provided new opportunities for the activation of strong carbon chlorine bonds and enabled the valorization of cheap and readily available chlorinated starting materials. Thus far, however, it has mainly explored strongly reducing conditions, which restrict the available chemical space to radical or anionic reactivity. Here, we demonstrate a radical-polar crossover process involving cationic intermediates, which enable chemodivergent functionalization of chlorinated benzamide derivatives in aqueous solutions. The reaction can be guided towards either C H arylation or N dealkylation by simple adjustment of reaction parameters such as the amount of water, the type of surfactant or the amine. The system operates under mild conditions where methylene blue is used as a photocatalyst and blue light emitting diodes are the light source. Tuning the reaction environment not only affects the selectivity of the ionic process, but also alters the mechanism of substrate activation - different forms of the photocatalyst are involved in each of the two reactions.