Furan Derivatives Research Articles

Experimental and Theoretical Analysis of the Thiol-Promoted Fragmentation of 2-Halo-3-tosyl-oxanorbornadienes.

2-Halo-3-tosyl-oxanorbornadienes are able to accept two thiol molecules through an initial nucleophilic substitution, giving isolable oxabicyclic thiovinyl sulfones that, subsequently, can react with a second thiol molecule via thio-Michael addition. The resulting oxanorbornenic thioketals undergo retro-Diels-Alder (rDA) fragmentation to release a furan derivative and a ketene S,S-acetal. The substitution pattern of the oxanorbornadienic skeleton influences the rate of the rDA through electronic and steric factors examined by quantum mechanical calculations.

Aroma Profile of Grapevine Chips after Roasting: A Comparative Study of Sorbara and Spergola Cultivars for More Sustainable Oenological Production

This study aimed to compare the aroma profiles of Sorbara and Spergola grapevine prunings roasted at different temperatures (120, 140, 160, 180, 200, and 240 °C). One potential application of grapevine prunings is their use as infusion chips to enhance and improve the aging processes of alcoholic beverages and vinegars. Aromatic compounds impart unique flavors and contribute to the complexity of the final products. Thermogravimetry–mass spectrometry coupled with evolved gas analysis (TGA-MS-EGA) was conducted to identify the thermal steps at which substantial changes occurred in the wood matrix. Solid-phase microextraction–gas chromatography–mass spectrometry (SPME-GC-MS) was used for the analysis of volatile compounds. Several key volatile compounds were identified, showing variations in their concentrations as a function of cultivar and roasting temperature. Furan derivatives, such as furfural, and phenolic compounds, such as guaiacol and vanillin, were the two main chemical classes of volatile compounds that predominantly defined the aroma of grapevine chips roasted above 180 °C. At lower roasting temperatures, some aldehydes, such as hexanal and terpenes, defined the aroma profiles of the samples. By repurposing waste materials, this application offers a pathway for environmentally conscious viticulture and sustainable practices within the food industry.

An Overview on Production of Lignocellulose-Derived Platform Chemicals Such as 5-Hydroxymethyl Furfural, Furfural, Protocatechuic Acid

Furan derivatives such as 5-hydroxymethyl furfural (HMF) and furfural (FA) and aromatic acids such as protocatechuic acid (PCA) represent the most essential classes of intermediates derived from lignocellulosic biomass. These bio-based compounds are potential feedstocks for producing bio-based chemicals and fuels. However, the derivatives of these bio-based compounds are useful in their antioxidative, antibacterial, and anti-aging activities. Protocatechuic acid (PCA, 2,3-dihydroxybenzoic acid), derived from lignin biomass, is also one of the essential bio-derived aromatic intermediates with an active acid and hydroxyl group, which can elevate it into an important class of potential platform chemicals for the production of value-added chemicals, such as HMF and furfuryl alcohol (FAL). The platform compounds are indeed the most used furan-based feedstocks since their chemical structure allows the preparation of various high-value-added chemicals. The related catalytic techniques are well known for the upgradation of biomass into these platform chemicals and their conversion into value-added chemicals. In this short review, we aim to briefly discuss biomass conversion into FA, HMF, and PCA and related heterogeneous catalytic processes. In addition, a few potential ongoing research trends are also proposed to provide some ideas for the further preparation of bio-based innovative derivatives in a much more green, simple, efficient, and economical way.

Palladium‐Catalyzed Oxidative Alkynylation of Allenyl Ketones: Access to 3‐Alkynyl Poly‐substituted Furans†

Comprehensive SummaryFurans bearing alkynyl substituents are highly useful in organic synthesis. However, the methodologies to access these important furan derivatives are rather limited. We herein report an efficient synthesis of alkynylated furan derivatives based on Pd‐catalyzed oxidative cross‐coupling reaction between allenyl ketones and terminal alkynes. This novel synthesis of alkynylated furans with wide substrate scope is operationally simple and tolerates various functional groups. Mechanistically, the formation of the palladium carbene through cycloisomerization and the subsequent alkynyl migratory insertion are proposed as the key steps in the transformation. The reaction reported in this paper further demonstrates the generality of the carbene‐based cross coupling.

Electrochemical Radical Reaction Construction of C-C Bonds: Access to 1,4-Dicarbonyl Compounds from Enol Acetates and 1,3-Diketones.

As important substrates for the construction of heterocycles, a simple and efficient approach for synthesis of 1,4-diones is highly desirable. In this work, novel and efficient electrochemical radical reactions of enol acetates and 1,3-diketones have been developed to successfully achieve 1,4-diketones under catalyst-free and oxidant-free conditions. The wide range of substrates, good group tolerance, and simple operation process make the approach have important practical value. Moreover, the obtained 1,4-diketones can be easily further transformed to pyrrole and furan derivatives.

Strategies for Improving Lignocellulosic Butanol Production and Recovery in ABE Fermentation by Tailoring Clostridia Metabolic Perturbations

The present study investigates approaches to enhance bio-butanol production using lignocellulosic feedstock via supplements of metabolism perturbation. Traditionally, bio-butanol has been produced through chemical synthesis in a process known as acetone–butanol–ethanol (ABE) fermentation. Today, biochemical techniques involving bacterial strains capable of producing butanol are used with renewable sources of biomass. In this study, a stepwise approach was tailored for metabolic perturbations to maximize butanol production from pure sugar and lignocellulosic feedstock as a reference model fermentation. In preliminary investigations, impacts of CaCO3, furfural and methyl red on cell growth, sugar utilization, acid production and butanol production were evaluated in glucose feedstock and xylose feedstock. Following the preliminary investigation, with supplementation of 4 g/L CaCO3, the concentrations of furan derivatives (75% furfural and 25% HMF) and ZnSO4 were optimized for maximal butanol production from glucose and xylose feedstocks, respectively. A final experiment of butanol production was concluded using lignocellulosic feedstock hydrolysate normally containing 0.5~1.5 g/L furan derivatives under optimized conditions of 2 mg/L ZnSO4 and 4 g/L CaCO3. Under optimized conditions, butanol production exceeded 10 g/L in wheat straw hydrolysate, which was significantly higher than that obtained in the absence of ZnSO4 and CaCO3. As compared to the traditional lignocellulosic feedstock post-treatment method, the metabolic perturbations method shows advantages in terms of productivity and economics.

Hydrothermal and thermal-acid pretreatments of wheat straw: Methane yield, recalcitrant formation, process inhibition, kinetic modeling

Bio-methanation of agro-residue could fulfill the rising energy demands and curb the environmental pollution. Nevertheless, hydrolysis is the rate limiting step in anaerobic digestion (AD) of agro-waste (wheat straw, WS) due to its recalcitrant lignocellulosic composition. Hydrothermal (100–175 °C, 30–120 min) and thermal-acid (100–175 °C, 0.5–2% H2SO4 v/v) pretreatments of WS were performed to assess the pretreatment effects on WS solubilization, recalcitrant formation, lignocellulosic composition and improvement in methane yield. The 60-min hydrothermal pretreatments had an optimum chemical oxygen demand (COD) solubilization. The hydrothermal pretreatment degraded predominantly the hemicellulose by 53.4%. The furan derivatives, i.e., furfural and 5-hydroxyl-methyl-furfural (5-HMF) were formed during hydrothermal pretreatment of WS at 175 °C. The furfural and 5-HMF were generated at all studied thermal-acid pretreatment conditions owing to hemicellulose solubilization. The anaerobic co-digestion (AcoD) of hydrothermally and thermal-acid pretreated WS was performed with food waste and cow manure in a batch assay. The hydrothermally pretreated WS showed 4–14% higher methane production, while the thermal-acid pretreated WS had 29–44% less methane production than untreated WS. High concentrations of furfural, 5-HMF, total volatile fatty acids (tVFA), and NH4–N affected the methane production in digesters treating thermal-acid pretreated WS. The kinetic analysis of the assays revealed that methane production was affected by furfural, 5-HMF, temperature and acid dosing. Therefore, the calculated values through modified Gompertz and logistic models deviated from the experimental values.

Development, Characterisation, and Performance Evaluation of Some Indigenous Plants for Faecal Sludge Treatment in Ghana

The search for alternative solutions for sustainable management of faecal sludge in the area of dewatering with biocoagulants/bioflocculants remains unfulfilled. Some available and accessible indigenous plants in the northern part of Ghana have been characterised and subsequently evaluated in their suitability for use as biocoagulant/bioflocculants. The Yila (Crossopteryx febrifuga) and the Voulo (Grewia mollis) plants were the indigenous plants used in this study. Three applications from the Yila wooden stem, the Yila bark, and the Voulo at different treatment concentrations with faecal sludge were monitored. The Yila wooden stem gave a potential of pollutant removal up to about 83.99%, 93.79%, and 91.54% for Chemical Oxygen Demand (COD), Total Suspended Solids (TSS), and turbidity, respectively. Application of the Yila bark gave a respective removal efficiency of up to about 77.39%, 82.02%, and 54.60% for COD, TSS, and turbidity. The efficiency of the Voulo plant obtained for COD, TSS, and turbidity was up to about 80.43%, 86.83%, and 72.55%, respectively. No cyanogenic or toxic compounds were identified in the characterised raw materials used for this study. The study has revealed the potential of producing biocoagulants that can perform as effectively as synthetic/chemical coagulants using locally natural raw materials but the use of it at large scale will only be applicable for batch or semi-batch systems. Some interesting constituents identified in the plants under consideration, such as trialkyl bismuthine and furan derivative, can open up opportunities to elucidate the potential applications of these identified plants in the areas of pharmaceuticals, cosmetics, glass and ceramics, rubber production, and other applicable medicinal advantageous areas.

Design and synthesis of 3,4-seco-lupane triterpene derivatives to resist myocardial ischemia-reperfusion injury by inhibiting oxidative stress-mediated mitochondrial dysfunction via the PI3K/AKT/HIF-1α axis

In this study, 86 new seco-lupane triterpenoid derivatives were designed, synthesized, and characterized, and their protective activities against ischemia-reperfusion injury were investigated in vitro and in vivo. Structure–activity relationship studies revealed that most target compounds could protect cardiomyocytes against hypoxia/reoxygenation-induced injury in vitro, with compound 85 being the most active and exhibiting more potent protective activity than clinical first-line drugs. Furthermore, all thiophene derivatives exhibited stronger protective activity than furan, pyridine, and pyrazine derivatives, and the protective activity gradually increased with the extension of the alkyl chain and changed in the substituent. The data from the in-vitro and in-vivo experiments revealed that compound 85 protected mitochondria from damage by inhibiting excessive production of oxidative stressors, such as intracellular ROS, which in turn inhibited the apoptosis and necrotize of cardiomyocytes and reduced infarct size, thereby protecting normal cardiac function. It was associated with enhanced activation of the PI3K/AKT-mediated HIF-1α signaling pathway. Therefore, compound 85 acts as an oxidative stress inhibitor, blocks ROS production, protects mitochondria and cells from myocardial ischemia/reperfusion (MI/R) injury, and represents an effective new drug for treating MI/R injury.

Synthesis and Biological Studies of Benzo[b]furan Derivatives: A Review from 2011 to 2022.

The importance of the benzo[b]furan motif becomes evident in the remarkable results of numerous biological investigations, establishing its potential as a robust therapeutic option. This review presents an overview of the synthesis of and exhaustive biological studies conducted on benzo[b]furan derivatives from 2011 to 2022, accentuating their exceptional promise as anticancer, antibacterial, and antifungal agents. Initially, the discussion focuses on chemical synthesis, molecular docking simulations, and both in vitro and in vivo studies. Additionally, we provide an analysis of the intricate interplay between structure and activity, thereby facilitating comparisons and profoundly emphasizing the applications of the benzo[b]furan motif within the realms of drug discovery and medicinal chemistry.

Green solvents to enhance hydrochar quality and clarify effects of secondary char

Several limitations hinder the industrial-scale implementation of hydrothermal carbonization (HTC) of biomass, especially the quality of as-carbonized hydrochar. This work investigates solvent extraction of hydrochars to enhance their potential applications. Hydrochars were produced at several HTC temperatures (190, 220, 250 °C) from cellulose and extracted using combinations of green polar solvents (ethyl acetate, acetone, and methanol). Results show that the composition of the extractable fraction resembles that of the HTC liquor, rich in carboxylic acids and furan derivatives, while the non-extractable solid phase shows improved thermal profiles devoid of highly volatile compounds. Carbon microspheres (non-dissolvable secondary char) are unaffected by extraction. The organics adsorbed on the hydrochar surface comprise highly volatile species and solvent washing effectively removes them.

Pyrolysis of waste printed circuit boards: Parametric effects on product distribution, characterization and gas emissions

The efficient and environmentally friendly disposal of waste printed circuit board (WPCB) is of great significance for resource sustainability. This study focuses on the pyrolysis process of WPCB and the comprehensive characterization of the products. Meanwhile, the emission properties of the main gas products in the pyrolysis process of WPCB were investigated in real time. The results of pyrolysis experiments indicated that a solid yield of 79.03% was obtained by pyrolysis at 500 °C for 60 min, and 91.46% of copper and 95.36% of tin were recovered. The gas products mainly consisted of CO, CO2, CH4, H2, and C2H2. The liquid products contained phenols, aromatic hydrocarbons, ketones and furan derivatives. The pyrolysis gas and liquid products might be utilized as the raw material for fuel and other composite materials after purification. The process combines medium-temperature pyrolysis and crushing processes to recover metal fractions and high-value products from WPCB. This provides a solution for the large-scale pyrolysis of electronic waste.

Hydroarylation of carbon–carbon double bond of furanic conjugated enones by arenes under superelectrophilic activation: synthesis and evaluation of antimicrobial activity of novel furan derivatives

Hydroarylation of carbon–carbon double bond of furanic conjugated enones by arenes under superelectrophilic activation: synthesis and evaluation of antimicrobial activity of novel furan derivatives

Exploring the Synthetic Chemistry of Phenyl-3-(5-aryl-2-furyl)- 2-propen-1-ones as Urease Inhibitors: Mechanistic Approach through Urease Inhibition, Molecular Docking and Structure-Activity Relationship.

Furan chalcone scaffolds belong to the most privileged and promising oxygen-containing heterocyclic class of compounds, which have a wide spectrum of therapeutic applications in the field of pharmaceutics, pharmacology, and medicinal chemistry. This research described the synthesis of a series of twelve novel and seven reported furan chalcone (conventional synthetic approach) analogues 4a-s through the application of microwave-assisted synthetic methodology and evaluated for therapeutic inhibition potential against bacterial urease enzyme. In the first step, a series of nineteen substituted 5-aryl-2-furan-2-carbaldehyde derivatives 3a-s were achieved in moderate to good yields (40-70%). These substituted 5-aryl-2-furan-2-carbaldehyde derivatives 3a-s were condensed with acetophenone via Claisen-Schmidt condensation to furnish 19 substituted furan chalcone scaffolds 4a-s in excellent yields (85-92%) in microwave-assisted synthetic approach, while in conventional methodology, these furan chalcone 4a-s were furnished in good yield (65-90%). Furan chalcone structural motifs 4a-s were characterized through elemental analysis and spectroscopic techniques. These nineteen (19)-afforded furan chalcones 4a-s were screened for urease inhibitory chemotherapeutic efficacy and most of the furan chalcones displayed promising urease inhibition activity. The most active urease inhibitors were 1-phenyl-3-[5-(2',5'-dichlorophenyl)-2-furyl]-2-propen-1-one 4h with an IC50 value of 16.13 ± 2.45 μM, and 1-phenyl- 3-[5-(2'-chlorophenyl)-2-furyl] -2-propen-1-one 4s with an IC50 value of 18.75 ± 0.85 μM in comparison with reference drug thiourea (IC50 = 21.25 ± 0.15 μM). These furan chalcone derivatives 4h and 4s are more efficient urease inhibitors than reference drug thiourea. Structure-activity relationship (SAR) revealed that the 2,5-dichloro 4h and 2-chloro 4s moiety containing furan chalcone derivatives may be considered as potential lead reagents for urease inhibition. The in silico molecular docking study results are in agreement with the experimental biological findings. The results of this study may be helpful in the future drug discovery and designing of novel efficient urease inhibitory agents from this biologically active class of furan chalcones.

Thermal decomposition behaviors and degradation kinetics of biobased polyesters with partial crosslinking to eliminate cyclic compounds

A series of poly(butylene adipate-co-butylene itaconate) (PBAPI) copolyesters with and without a small amount of ethylenediaminetetraacetic acid (EDTA) were synthesized via melt polymerization. Thermogravimetric analysis -gas chromatography/mass spectroscopy (TGA-GC/MS) techniques were used to identify the thermal degradation behaviors. By introducing 0.1 mol % EDTA into BA/BI = 10/0, the dominant degradation product was converted from furan and cyclopentanone derivatives to CO2 and formation of cyclic compounds was notably inhibited. Moreover, similar tendencies were observed when the BI content increased, demonstrating that the existence ratio of CO2 and furan derivatives increased while the concentrations of cyclopentanone and cyclic compounds reduced during decomposition. Finally, no cyclic compound product was detected in the BA/BI = 7/3 copolyester. These results indicate that the introduction of both EDTA and BI inhibits generation of cyclic compounds, which are attributed to the formation of partial crosslinking for chemical structures. The nonisothermal degradation kinetic was also carried out to investigate the decomposition behaviors. The activation energy requirements at each degradation stage varied with the composition of BA/BI ratios and the introduction of EDTA, demonstrating further evidence of degradation behavior transformation.

Robust Pd/Al2O3 bifunctional catalyst for single reactor tandem synthesis of furan and tetrahydrofuran derivatives from furfural

In this study, we report a reusable catalytic system based on a bifunctional Pd/Al2O3 spheres to conduct the single-reactor tandem aldol condensation/crotonization reaction between furfural and methylisobutyl ketone, followed by hydrogenation, both in batch and continuous mode. In batch mode, the process achieved an overall 86 % yield of 1-(tetrahydrofuran-2-yl)-5-methylhexan-3-one at 180 °C after 9 h at (5.2 wt% furfural concentration). The reaction rate for the aldol condensation/crotonization step decreased at higher FF concentration, suggesting the inhibition of Lewis acid centers due to adsorbed FF as inferred from kinetic modeling. In continuous mode, the catalyst was operated in a dual-type fixed bed reactor and reached 55 % steady-state conversion and 60 % and 35 % selectivity to 1-(furan-2-yl)-5-methylhexan-3-one and (E)-1-(furan-2-yl)-5-methylhex-1-en-3-one, respectively, after 12 h operation at 170 °C and a weight-hourly space velocity of 0.50 h−1 at high furfural concentration (18 wt%). NH3/CO2 temperature-programmed desorption and FT-IR spectroscopy implemented with adsorbed pyridine, NH3 and CO2 were used to assess the nature, strength, density and stability of the acid and basic sites.

Transfer hydrogenation of furfural to furfuryl alcohol under microwave irradiation using mixed oxides.

The reaction to obtain furan alcohols is one of the most important in the upgrading of furan derivates. An attractive route is the transfer hydrogenation of furfural using acidic-basic catalysts. In this work, mixed oxides derived from ternary hydrotalcites were employed to obtain furfuryl alcohol from furfural assisted by microwave irradiation. The reaction was studied using containing Co2+ and Ni2+ in their structure and was then optimized using distinct primary and secondary alcohols as hydrogen donor sources, as well as distinct temperatures and initial concentrations of furfural. The yields to furfuryl alcohol are strongly dependent on the type of Me2+ in layered oxides mainly due to higher basicity and also to the donor employed in the reaction. The mixed oxide containing Co2+ showed complete conversion of furfural and higher yields to furfuryl alcohol (> 95%) at short times of reaction (< 1 h).

Study on the influence of chain extension and substituent position on charge transport properties and optoelectronic properties based on 2,5-di(pyrazine-2-yl)furan derivatives

In this paper, the basic structure of 2,5-di(pyrazine-2-yl)furan (DPF) was initially designed to tune the charge transport properties and photoelectric properties of organic materials by chain extension. Through the calculation of recombination energy, the structure with the introduction of anthracene group (DPF-A) is a stable P-type material with the smallest recombination energy in terms of adiabatic ionization potential, so the chain extended molecule DPF-A was selected as the base for the study of substituent positions. While thiophene, trifluorinated acyl, and methoxy groups were introduced to design DPF-A series derivatives. Density functional theory with high computational accuracy was applied to investigate geometric structure, orbital energy levels, ionization energy, electron affinity energy, and recombination energy. The results show that the increase (decrease) of the HOMO (LUMO) energy level leads to the red (blue)-shift of absorption wavelength and fluorescence emission wavelength; the vertical ionization potential decreases and the vertical electron affinity potential increases, thus the hole and electron injection barrier decreases; the decrease of the hole/electron recombination energy improves the charge transport ability of the molecule. Moreover, the adjustment of thiophene orientation and the position of the introduced group has the potential to transform the p-type material into an n-type material, resulting in the enhanced electron injection ability.

Comprehensive binding analysis of glycated myosin with furan derivatives via glucose by means of multi-spectroscopy techniques and molecular docking simulation

Myosin is an ideal binding receptor for aroma compounds and its functional properties are easily affected by glucose. The study comprehensively clarified the effects of glucose glycation-induced structural modifications of myosin on its binding ability with furan derivatives, including 2-methylfuran, 2-furfural, and 2-furfurylthiol. The results demonstrated that the binding levels of furan derivatives were obviously affected by the glycation levels of myosin due to the changes of myosin structure and surface. The increased glycation levels caused the unfolding of myosin structure and accelerated the aggregation, as were exhibited by the data of zeta potential, particle size, microstructure, and secondary structure. The glycated myosin with wrinkled surfaces favored the significant increase of hydrophobic interactions (31.59–69.50 μg), the more exposure of amino acid residues (3459–6048), the formation of free sulfhydryl groups (16.37–20.58 mmol/104g) and hydrogen bonds. These key (non)covalent linkages accounted for the generation of glycated myosin-odorants complex, including 2-furfurylthiol (29.17–47.87 %), thus enhancing the resultant binding ability as evidenced by the free furan derivatives concentrations, fluorescence quenching and molecular docking simulation analysis. The glycated myosin for 8 h bound highest concentrations of furan derivatives. The results will provide comprehensive data on the retention of aroma compounds in meat products.

Appraisals on the anticancer properties of Mentha species using bioassays and docking studies

The medicinal properties of Mentha species are highly regarded due to their pro-health biological properties. This study aimed to investigate the fractions and bioactive compounds that are responsible for anticancer properties of the Mentha species. Firstly, the cytotoxic effects of leaves and hairy roots extracts from two Mentha species including Mentha piperita L. and Mentha spicata L., were assessed by MTT assay. Then, a bioassay-guided fractionation of an extract with higher toxicity against cancer cells was conducted to yield the bioactive compound. Among all the four extracts tested, the leaf extract of M. piperita possessed the greatest cytotoxic activity against A549, MCF-7, and PC-3 cells. Bioassay-guided fractionation revealed that the purified fraction showed a cytotoxic effect (IC50 =54.8 μg/mL) against the PC-3 cancer cell line and exhibited potent anticancer activity by inducing apoptosis and wound healing properties, as well as upregulating the expression of tumor suppressor genes. Analytical investigations on the purified fraction utilizing LC-MS NMR, and FT-IR methodologies indicated that the identified anticancer metabolite was considered as a furanic compound called 2-ethylhexyl 5-hydroxyfuran-2 carboxylate, which is reported for the first time here. Molecular docking analyses indicated that the furan derivative has a great potential to differentially interact with cancer-related receptors. Therefore, this evidence suggests that the Mentha species has valuable anticancer bioactive compounds that could be considered in phytochemical-based cancer therapy programs.