Direct conversion of phenols into primary anilines with hydrazine catalyzed by palladium

Downstream processing of lignin derived feedstock into end products

This review provides critical analysis on various downstream processes to convert lignin derived feedstock into fuels, chemicals and materials.

Direct synthesis of novel quinoxaline derivatives via palladium-catalyzed reductive annulation of catechols and nitroarylamines

A palladium-catalyzed new hydrogenative annulation reaction of catechols and nitroarylamines, allowing straightforward access to two classes of novel quinoxaline derivatives, has been demonstrated.

Heteroatom-participated lignin cleavage to functionalized aromatics

Heteroatom-containing reagents triggered the catalytic cleavage of lignin linkages and functionalization of products simultaneously.

Construction of Spirocyclic Tetrahydro-β-carbolines via Cross-Annulation of Phenols with Tryptamines in Water

Phenols are readily available by degradation of lignin resource. Palladium-catalyzed conversion of phenols to tetrahydro-β-carboline skeletons bearing a spirocycle at the C-1 position in water is reported. Various substituted phenols are successfully cross-annulated with different tryptamines via sequential C(Ar)-O bond cleavage of phenols, C-H bond activation of tryptamines, and C-N/C-C bond formations. This method provides a new protocol of converting lignin phenols into high-value-added compounds, such as natural product Komavine.

Direct Synthesis of Diphenylamines from Phenols and Ammonium Formate Catalyzed by Palladium

Arylamines are commercially and synthetically useful compounds with a wide variety of applications. Their preparation has been traditionally achieved using metal-catalyzed C-N coupling reactions with aryl halides. In this work, 17 different diarylamines are prepared from phenols by using ammonium formate as the aminating reagent. Phenolic compounds are more desirable feedstocks, owing to their availability from lignin, making them valuable biorenewable alternatives to aryl halides. Ammonium formate is found to be a convenient surrogate for ammonia and a useful aminating reagent for phenols. Diarylamine products are obtained in good to excellent yields while only water and CO₂ are generated as byproducts of the transformation.