Preparation of monolignol γ-acetate, γ-p-hydroxycinnamate, and γ-p-hydroxybenzoate conjugates: selective deacylation of phenolic acetates with hydrazine acetate

We report here a reliable and facile synthesis of a range of monolignol gamma-p-hydroxycinnamate (including p-coumarate, ferulate, and caffeate), gamma-acetate, and gamma-p-hydroxybenzoate conjugates, many not previously reported, that are either putative intermediates in the biosynthesis of natural lignins or new monomer-conjugates destined for upcoming designer lignins. The key was the development of a highly selective deacylation approach for phenolic acetates; i.e., a method that cleaves phenolic acetates while leaving the sensitive monolignol ester conjugates intact.