Organophotoredox‐Catalyzed Postfunctionalization of Poly(methacrylate) Derivatives via Radical–Polar Crossover Phosphonylation

Abstract Photoredox‐catalyzed postfunctionalization of poly(meth)acrylate‐based copolymers bearing phthalimide moieties can produce novel polymer architectures that are inaccessible using polymerization approaches; however, this method is restricted to radical reactions. To expand the scope of reactions applicable to photoredox‐catalyzed postfunctionalization, this study focused on the radical–polar crossover (RPC) process, in which a carbocation equivalent is generated to react with nucleophiles. The organophotoredox‐catalyzed reaction of a random copolymer of N ‐(methacryloxy)phthalimide and methyl acrylate using trialkyl phosphite nucleophiles afforded the corresponding phosphonate‐containing polymers. Although simultaneous hydrogenation was inevitable, a novel polymer comprising dialkyl isopropenylphosphonate, propylene, and methyl acrylate units was obtained, which is of interest because phosphonate‐containing polymers are potentially applicable as thermoresponsive materials, flame‐retardant materials, and additives in Li‐ion batteries. A series of copolymers with different components were successfully applied to the postfunctionalization method. The organophotoredox catalysis‐based postfunctionalization strategy developed in this study provides versatile functional polymers in a simple, green, and sustainable manner.