An indolizidine alkaloid, (−)-8a-epi-lentiginosine was synthesized from d-glucose using the Pd-BiPhePhos catalyzed intramolecular Tsuji–Trost reaction of non−derivatized allylic alcohol as a key construction of the hydroxylated pyrrolidine ring to give the desired product in good yield and high stereospecificity (dr = 97:3). The absolute configuration and structure of (−)-8a-epi-lentiginosine were confirmed by NMR and X-ray crystal structure analysis. The crystal structure of (−)-8a-epi-lentiginosne showed the envelope conformation of the five-membered ring, which is an N-atom in the endo-position, and the fused six-membered ring adopts a chair conformation similar to the DFT optimized structure. The solid-state packing is dominated by a 1D-hydrogen-bonded network along the a-axis involving both hydroxyl groups and the amine. The large HOMO–LUMO energy gap indicated the high stability of the compound.

Bark represents 10 % dry weight of spruce trees and is a major side stream from pulp production. Currently, pulp mills burn bark to produce energy with a low economic value, directly emitting biogenic carbon dioxide to the atmosphere. Biorefining bark using a continuous flow-through fractionation process generates high added-value compounds (tall oil, starch, phenol, and pulp) that allow for extended carbon storage durations. This study assesses the potential future environmental impacts of valorising bark instead of burning it. We conduct a LCA study combining a prospective consequential modelling perspective with an input-related functional unit and account for the effects of storing biogenic carbon in the bark-based products. Our findings show that biorefining bark maintains lower environmental impacts than combustion, reducing time-differentiated climate impacts by up to 30 %, but only when the carbon dioxide used for pulping is recirculated and the fractionation processes are integrated with a co-located pulp mill supplying surplus waste energy, considered to have no associated environmental impacts. Storing biogenic carbon for a longer period of time has a positive effect on mitigating short-term climate impacts. However, our analysis reveals that while time-dependent climate impacts decrease, there is an increase in human toxicity and ecotoxicity impacts, with combustion performing better in these categories. This highlights the importance of expanding the scope of LCA studies to include impacts beyond climate change. Overall, this work demonstrates that combining a prospective consequential modelling perspective with an input-related functional unit is a relevant approach to study potential future impacts of emerging biorefineries and thus supports the development of a sustainable circular bioeconomy.

α-Amino ketones were synthesized by a Meinwald rearrangement of biomass-based amino epoxides using copper(II) triflate as a catalyst. The regioselectivity of the rearrangement can be rationalized in terms of the reaction proceeding via the most stable carbocationic intermediate to give various α-amino α′-aryl ketones in moderate to good yields. This is an attractive method to prepare α-amino ketones using a benign and inexpensive catalyst.

A novel combination of strong Brønsted acidity (B), from propyl sulfonic acid functionalized on H–Y zeolite (HY-PrSO3H); Lewis acidity (L), by dispersion of SnO2; and confinement control showed high reactivity and selectivity in the conversion of cellulose to ethyl levulinate (EL). An optimal catalyst for EL formation was found by combining the Faujasite (FAU) structure, which incorporates strong Brønsted and Lewis acids in a B/L acidity ratio of 3.9. The resulting catalyst showed high yield of EL 63.7, 57.6 and 24.8%, from fructose, glucose, and empty palm fruit bunch (EFB), respectively. By isolating the cellulose from EFB, the yield from cellulose in EFB could be increased to 42.8% with a selectivity of 74.8%. Moreover, the catalyst could be reused up to 3 times with decreased of EL formation; and moreover, 90% of initial activity was regained after regeneration.

Condensation of glycerol with bioderived carbonyls yields cyclic ketals with unique properties. In this study, efficient solvent-free heterogeneously catalyzed ketalization has been achieved to give the corresponding products in good to excellent yields. Substrate-to-glycerol ratios of 1:1 have been used; the reactions were performed at 120 °C for 30 min. By using an acid-treated H-ZSM-5 catalyst, high selectivity to a five-membered ring was achieved. Furthermore, the catalyst could be recycled up to 4 times without losing activity. The ketal from glycerol and levulinic acid (GLK) was isolated and applied as a solvent in oil color paint and showed advantageous properties over commercial paint solvents in terms of aging.

A stereospecific deoxygenation of trans-epoxy cinnamic acid derivatives to access (Z)-cinnamamides, (Z)-cinnamyl alcohol and (Z)-cinnamyl amines using a catalytic system based on nickel triflate and triphenylphosphine has been developed. The desired products were obtained in good to excellent yield (up to 92 % isolated yield) and excellent stereospecificity (Z: E ratio up to>99: 1). The transformation has a broad functional group tolerance including amides, amines, alcohols and esters. The power of the methodology was demonstrated in the key step of the total synthesis of biologically active natural product, N-cis-feruloyl tyramine from readily available trans-ferulic acid. A reaction mechanism involving activation of epoxide via coordination of the oxygen atom and the neighboring O- or N-atoms to the nickel catalyst and formation of Ph3P-carbon bond is proposed. This method is important for synthesis of highly desirable functionalized (Z)-alkenes from readily available (E)-alkenes.

Polyethylene terephthalate (PET) is one of the most common plastics and can be cascaded mechanically during its life cycle. However, recycling affects the mechanical properties of the material, and the virgin material is constantly in demand. If a worn material could be depolymerized to its chemical building blocks, then a virgin polymer could be generated from old fibers. In this work, we have developed a benign organo-catalytic depolymerization of PET to yield dimethyl terephthalate (DMT) and ethylene glycol (EG) without the need for purification of generated monomers. By recirculating the solvent and organo-catalyst, a solvent/substrate ratio of 3:1 was achieved. The depolymerization was successfully applied to other polyesters, polycarbonates, and polycotton. The cotton isolated from the polycotton depolymerization was successfully processed into viscose fibers with a tenacity in the range of nonwaste cotton-derived viscose filaments. The global warming potential (GWP) of PET depolymerization was evaluated by using life cycle assessment (LCA). The GWP of 1 kg PET recycling is 2.206 kg CO₂ equivalent, but the process produces DMT, EG, and heat, thereby avoiding the emissions equivalent to 4.075 kg CO₂ equivalent from the DMT, EG, and steam-energy production through conventional pathways. Thus, the net result potentially avoids the emission of 1.88 kg of CO₂ equivalent. The impact of this process is lower than that of waste PET incineration and conventional PET recycling technologies.

Lignocellulose is mainly composed of hydrophobic lignin and hydrophilic polysaccharide polymers, contributing to an indispensable carbon resource for green biorefineries1,2. When chemically treated, lignin is compromised owing to detrimental intra- and intermolecular crosslinking that hampers downstream process3,4. The current valorization paradigms aim to avoid the formation of new C–C bonds, referred to as condensation, by blocking or stabilizing the vulnerable moieties of lignin5–7. Although there have been efforts to enhance biomass utilization through the incorporation of phenolic additives8,9, exploiting lignin’s proclivity towards condensation remains unproven for valorizing both lignin and carbohydrates to high-value products. Here we leverage the proclivity by directing the C–C bond formation in a catalytic arylation pathway using lignin-derived phenols with high nucleophilicity. The selectively condensed lignin, isolated in near-quantitative yields while preserving its prominent cleavable β-ether units, can be unlocked in a tandem catalytic process involving aryl migration and transfer hydrogenation. Lignin in wood is thereby converted to benign bisphenols (34–48 wt%) that represent performance-advantaged replacements for their fossil-based counterparts. Delignified pulp from cellulose and xylose from xylan are co-produced for textile fibres and renewable chemicals. This condensation-driven strategy represents a key advancement complementary to other promising monophenol-oriented approaches targeting valuable platform chemicals and materials, thereby contributing to holistic biomass valorization.

This study presents a sequential fractionation of spruce bark employing a flow-through system that enables continuous extraction without the need to change the chamber during the process. Various bark components such as lipophilic extractives, noncellulosic sugars, and lignin were extracted under mild conditions and within short timeframes compared to the batch process. The utilization of the flow-through system enabled efficient extraction without degradation of products that were observed during the batch process. By recirculating the solvents containing extracted components, the solvent/biomass ratio could be reduced considerably, without degradation of the products. The results demonstrate an energy efficient approach to obtaining valuable components from spruce bark, paving the way for a future biorefinery.