Simple method for synthesizing phenolic β-O-4 dilignols

Abstract

A modified synthetic method for phenolic β-O-4 lignin substructure model dimers was developed involving protection of the phenolic hydroxyl group of acetophenons with benzoyl chloride, bromination with 4-dimethylaminopyridiniumbromide perbromide, condensation with phenols in the presence of 18-crown-6-ether, condensation with paraformaldehyde, reduction with NaBH4, and debenzoylation. This method results in shorter reaction times and increasing yields without the application of strict anhydrous and drastic conditions or chloric solvents. This alternative route could be applied to the β-O-4 dilignol syntheses of four combinations of guaiacyl and syringyl derivatives. © The Japan Wood Research Society 1999.