Redox-neutral photocatalytic cleavage and $gem$-difluoroalkenylation of lignin linkages

Abstract

The conversion of lignin into high–value-added chemicals represents a promising strategy to enhance its valorization. However, developing catalytic systems and reagents that enable the selective activation and functionalization of specific linkages within its complex polymeric structure remains highly challenging. Here, we report a photocatalytic method for the efficient cleavage and gem -difluoroalkenylation of β-O-4 and β-1 lignin models, as well as native lignin biomass. By using α-trifluoromethyl alkenes as functionalization reagents, this protocol provides a wide array of valuable gem -difluoroalkenes through proton-coupled electron transfer (PCET), β-scission, radical addition, and β-F elimination processes. This redox-neutral method features operational simplicity, good functional group compatibility, and excellent selectivity. In addition, the derivatization of the resulting gem -difluorobishomoallylic alcohol highlights its synthetic potential.