Mono- and Bisphosphonylation of Aryl Chlorides via Phenothiazine Organophotoredox Catalysis

Aryl phosphonates are important structural motifs in a variety of fields, including pharmaceuticals and functional materials. While methods for the phosphonylation of aryl iodides and bromides have been widely developed, the corresponding transformation of aryl chlorides remains relatively unexplored due to the high energy barrier associated with the activation of C(sp²)-Cl bonds. In particular, bisphosphonylation of aryl chlorides remains largely unexplored. Here, we report the mono- and bisphosphonylation of aryl chlorides using a phenothiazine organophotoredox catalyst. The reaction is applicable to various mono- and bischlorinated benzenes to obtain the corresponding aryl phosphonates. This method offers versatile access to functionalized aryl phosphonates, thus rendering it a promising tool for the synthesis of pharmaceuticals and functional materials.