Synthesis of biomass-based amines: Metal-free catalytic reductive amination of xylose and biomass-derived carbonyl compounds using pyridine-based ionic liquid/triethoxysilane

Abstract

Conversions of biomass into value-added nitrogen-containing compounds such as furfurylamines are industrially demanding, contrarily, highly challenging. In this work, we present the synthesis of N-substituted furfurylamines from xylose/biomass-derived carbonyl compounds utilizing novel [Pro(Etpy)3][Lac]3 ionic liquid (IL) coupled with (EtO)3SiH as a reductive agent, which offers a metal-free alternative route with mild reaction conditions. Besides, reductive amination of a wide variety of biomass-derived carbonyl compounds proceeded in 25–92% yield, whereas, conversion of xylose to furfural followed by reductive amination gave 59–72% yield of furfurylamines by using [Pro(Etpy)3][Lac]3 IL catalyst with (EtO)3SiH. The one-pot three-step procedure is highly efficient for the synthesis of furfurylamines from xylose as it avoids isolation of furfural and requires a single catalyst for three different steps. Additionally, this IL demonstrates excellent recyclability and selectivity substantiating industrial feasibility. Overall, we present a simple yet efficient integrated approach to overcome the problems associated with the separation and purification of intermediates (i.e, furfural), which saves energy, solvent, cost, and time. The synthesized IL showed excellent catalytic activity towards the synthesis of industrially essential molecules containing N-substituted furfurylamines.