Cu-Catalyzed Funneling Oxidation Enables C-C Bond Cleavage in Lignin-derived Compounds.

The structural complexity and chemical heterogeneity of lignin present a formidable barrier to its use as a sustainable replacement for petroleum-derived aromatics. Here, we report a robust, earth-abundant copper/nitroxyl catalytic system that achieves the aerobic oxidative funneling of crude, non-pre-fractionated reductive catalytic fractionation (RCF) lignin oil into a single, high-value platform chemical: 2,6-dialkoxybenzoquinone. This transformation operates via a cooperative proton-coupled electron transfer (PCET) mechanism to cleave robust aromatic-aliphatic C-C bonds under mild aerobic conditions (O2 or open air). Using various alcohols as both solvent and nucleophile, the reaction provides modular access to a library of 2,6-dialkoxybenzoquinones in up to 86% isolated yield from model monomers/dimers and an impressive 27 wt % yield (gram product per gram lignin) directly from high-S poplar wood lignin oil (62 mol % convergent yield based on the S-phenol equivalents in the lignin oil). Crucially, we demonstrate that these tunable biomass-derived quinones serve as highly versatile synthons for advanced chemical synthesis to access precursors of bioactive natural product (scutellarein), organic electronics (TCNQ-type acceptors), platform building blocks (1,4-cyclohexanediol), cross-coupling reactions, and a modified high-performancepolyether ether ketone (PEEK) polymer. This work establishes a bridge connecting raw biomass fractionation to diverse applications in synthetic chemistry and materials science.