Sustainable decarboxylative functionalization enabled by a recyclable multichromophore polymer photocatalyst under visible light

Abstract: Decarboxylative functionalization of aliphatic carboxylic acids has emerged as a powerful platform for accessing alkyl radicals from abundant, stable, and structurally diverse feedstocks. Because such acids are prevalent in natural products and pharmaceuticals, they serve as attractive substrates for late-stage diversification. However, many existing decarboxylative methodologies rely on metal catalysts, specialized additives, or homogeneous photocatalysts that are costly, difficult to recover, and challenging to reuse, limiting their sustainability. Herein, we report the development of a recyclable polymeric photocatalyst incorporating three complementary chromophores that operate cooperatively under visible light irradiation. This multichromophoric design enhances light absorption and promotes efficient charge separation, enabling the generation of alkyl radicals via smooth decarboxylation. The resulting strategy facilitates metal-free sulfonylation and fluorination of aliphatic carboxylic acids across a broad substrate scope, delivering good yields while maintaining excellent tolerance to sensitive functional groups under mild conditions. Importantly, the polymer photocatalyst is synthesized in a single step, can be readily recovered, and retains its photocatalytic efficiency over multiple cycles with minimal loss of activity. This work highlights the potential of multichromophore polymer photocatalysts as robust, reusable platforms for sustainable decarboxylative radical chemistry, offering a practical alternative to conventional small-molecule and metal-based photocatalysts.