Sustainable Production of Amide-Based Fungicidal Agents from Lignin β-O-4 Motifs and Alcohols

The catalytic conversion of lignin into N-containing aromatic compounds expands lignin’s potential for high-value agrochemicals. However, achieving selective C–C bond cleavage and subsequent C–N bond formation with compatible catalysts remains challenging. This work reports an inexpensive CuI-catalyzed oxidative amidation of lignin β-O-4 moieties, primary alcohols, and secondary alcohols with aromatic amines under an oxygen atmosphere, yielding diverse functionalized aromatic amides in moderate to high yields, up to 86%. Mechanistic investigations suggest a reaction pathway involving the selective oxidation of benzylic alcohol, followed by the key C–C bond cleavage, C–N bond formation, and final dehydrogenative oxidation. Furthermore, bioassay results showed that most of the synthesized amide derivatives exhibit superior antifungal efficacy against six plant-pathogenic fungi compared with the commercial fungicides ethylicin and azoxystrobin at 100 μg/mL. Here, we present a practical protocol for synthesizing aromatic amides that effectively links lignin valorization to crop-protection chemicals.