A chemoenzymatic cascade for sustainable production of chiral N-arylated aspartic acids from furfural and waste

Abstract

Both biomass valorization and waste upcycling are important routes to sustain the circular bioeconomy. In this work, we present a chemoenzymatic cascade for selective synthesis of chiral N-arylated aspartic acids from biomass-derived furfural and waste nitrophenols (NPs) by merging robust photo- and electrocatalysis with stereoselective biocatalysis. Concurrent photoelectrocatalytic oxidation of furfural into maleic acid (MA) and fumaric acid (FA) was significantly enhanced by combining catalyst and reaction engineering strategies including identification of a powerful photocatalyst meso-tetra(4-carboxyphenyl)porphyrin, continuous flow technique, enhancing dissolved O₂ and paired electrosynthesis. The overall space-time yield (STY) approached 2.8 g L⁻¹ h⁻¹ in a fed-batch process, with the product titer of 28.3 g L⁻¹. Besides, photoelectrosynthesis of MA/FA was effectively fueled by sunlight, with the STY of up to 3.6 g L⁻¹ h⁻¹. Both MA selectivity and yield could be facilely improved to around 89% by reducing the buffer concentrations. Paired electrosynthesis strategy not only resulted in greatly improved MA production at the anode, but also enabled NPs upcycling into value-added aminophenols (APs) at the cathode. The products formed in the two electrode chambers were converted into N-arylated (S)-aspartic acids by a bienzymatic cascade. This work presents a multicatalytic approach for integrating selective biomass valorization and waste upcycling towards sustainable manufacture.