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.