Production of polysubstituted pyrroles from lignin β-O-4 models via a one-pot multicomponent reaction

The synthesis of N-bearing heterocyclic chemicals from renewable lignin remains a huge challenge due to the intricate lignin internal structure as well as the cover of multi-step process, generally involving the breakage of lignin CO or CC bonds and the generation of CN bonds and N-heterocyclic ring. Herein, a general synthesis of pyrroles from lignin β-O-4 segments, amines, and vicinal diols via ruthenium-catalyzed three-component reaction has been provided. Mechanistic studies indicate the transformation includes highly-coupled cascade steps of catalytic dehydrogenation, CN and CC bond formations, as well as two dehydration reactions. Through our protocol a variety of functionalized pyrroles were developed from lignin β-O-4 models, showing the potential of biomass in pharmaceutical synthesis field.