Current Organic Synthesis - Volume 22, Issue 1, 2025

Nanocellulose is not only a biocompatible and environmentally friendly material but also has excellent mechanical properties, biodegradability, and a large number of hydroxyl groups that have a strong affinity for water. These characteristics have attracted significant attention from researchers in the field of glucose sensing.

This review provides a brief overview of the current research status of traditional materials used in glucose sensors. The sensing performance, chemical stability, and environmental properties of nanocellulose-based glucose sensors are compared and summarized based on the three sensing methods: electrochemical sensing, colorimetric sensing, and fluorescence sensing. The article focuses on recent strategies for glucose sensing using nanocellulose as a matrix. The development prospects of nanocellulose-based glucose sensors are also discussed.

Nanocellulose has outstanding structural characteristics that contribute significantly to the sensing performance of glucose sensors in different detection modes. However, the preparation process for high-quality nanocellulose is complicated and has a low yield. Furthermore, the sensitivity and selectivity of nanocellulose-based glucose sensors require further improvement.

Nowadays, macrocyclic compounds constitute a privileged source for the development of compounds with interesting biological properties. Ring-closing olefin metathesis has received great attention for the synthesis of small, medium, and larger ring systems.

In the present work, we described the synthesis of eight original pyridyl macrocyclic triarylmethanes using an efficient 3-step synthetic strategy. The bisalkylated 4,4'-(pyridin-X-ylmethylene) diphenols (X = 2 - 4) were prepared by ring-closing metathesis as macrocyclization key step, using Grubbs second generation catalyst.

The pyridyl macrocyclic triarylmethanes were obtained with moderate to good yields. The introduction of a pyridine N-oxide moiety before the macrocyclization proved to be interesting to afford a higher yield of the corresponding metathesis product. FT-IR, ¹ H NMR, ¹³C NMR, and X-ray diffraction analysis have been used for the characterization of the synthesized compounds.

The synthetic strategy used here proposes an efficient alternative to prepare macrocyclic triarylmethanes of different sizes.

Previous studies have reported various biological activities of indenopyridazine and thiazole derivatives, including antiviral activity and CoV-19 inhibition. In this paper, the authors aimed to design, synthesize, and characterize a novel series of indenopyridazinethiazoles, starting with 2-(4-cyano-3-oxo-2,3-dihydro-9H-indeno[2,1-c]pyridazin-9-ylidene)-hydrazine-1-carbothioamide and available laboratory reagents.

The strategy involved the synthesis of indeno[2,1-c]pyridazincarbothioamide, followed by its reaction with various hydrazonoyl chlorides and α-halocompounds (phenacyl bromides and α-chloroketones) to obtain the desired indenopyridazinethiazole derivatives. The synthesized structures were confirmed using IR, NMR, mass spectra, elemental analysis, and alternative synthesis when possible. Docking scores and poses of thirteen synthesized compounds were examined using AutoDock4.2.6 software against multiple targets of SARS-CoV-2, including 3C-like protease (3CL^pro), helicase, receptor binding domain (RBD), papain-like protease (PL^pro), neuropilin-1 (NRP-1), RNA-dependent RNA polymerase (RdRp), and human angiotensin‐converting enzyme 2 (ACE2).

Docking predictions revealed that compound 13d exhibited high potency against 3CL^pro and helicase, with docking scores of -10.9 and -10.5 kcal/mol, respectively. Compound 10c showed superior docking scores against RBD and ACE2, with values of -8.7 and -11.8 kcal/mol, respectively. Compounds 10a, 13c, and 7b demonstrated excellent docking scores against RdRp, PL^pro, and NRP-1, with values of -10.3, -10.4, and -8.6 kcal/mol, respectively.

The authors recommend further experimental assessments of compounds 13d, 10c, 10a, 13c, and 7b against SARS-CoV-2 multi-targets, considering their promising docking scores.

The aims of this study are to synthesize new derivatives of sodium alginate that improve the inherent properties, such as hydrogel strengthening, and create environmental sensitivity, such as pH sensitivity, for use in drug delivery.

Today, hydrogels, due to outstanding properties such as biodegradability, biocompatibility, mechanical properties, and response to stimuli properties, are widely used as harmless biomaterials in various fields in drug delivery, wound dressing, and tissue engineering. Stimulus-sensitive polymers significantly respond to slight changes in their environment. Different types of stimuli are used to influence the properties of polymers, the most important of which are temperature and pH because these are two vital factors in the human body; hence, temperature-sensitive and pH-sensitive hydrogels have been extensively studied. The ability to absorb water and swell the hydrogel is due to hydrophilic chains in the hydrogel network, and water absorption by hydrogel can be controlled by response to the stimuli. Since hydrogels mimic human tissue, the ability to retain water in them is essential. As a result, it is considered in many biomedical drug delivery systems. Stimulus-responsive swelling can control diffusion out of and into the hydrogel network, which allows temporal and spatial control of drug release. When a drug is loaded onto a biodegradable and stimuli-sensitive hydrogel, the drug delivery system has the added advantage of sustained release of the drug, which reduces side effects.

In this study, two different hydrocarbons, [1,3-diaminopropane (DAP)] as a short-chain hydrocarbon, and [1,7-diaminoheptane (DAH)] as a long-chain hydrocarbon were grafted onto three types of sodium alginate (SA), through amide bond linkages. The hydrogel copolymer matrices were compared with sodium alginate (SA) beads. The graft copolymers were characterized using FTIR, ¹HNMR, XRD spectroscopy, elemental analysis (CHNS) and thermal analysis (TGA, DTA and DSC). An environmental scanning electron microscope (ESEM) was used to investigate the surface morphology of hydrogels.

Effects of variables such as the length of hydrocarbon chains cross-linked to alginate, temperature, pH, and cross-linkers on the properties of hydrogels investigated in the temperature range of 2-70˚C and two different pH values (4.4 and 7.4). The results showed that when the hydrocarbon chain length of diamines decreases, the extent of cross-linking and strength of the hydrogels are increased. Other results suggest that the hydrogels obtained from high-viscosity alginate derivatives had positive pH sensitivity. Hydrogels prepared in this study demonstrated good mechanical and swelling ratios that are necessary for wound dressing.

DAP-g-SA and DAH-g-SA pH-sensitive hydrogels were successfully synthesized through amide bond linkages. The new synthesis derivatives showed lower swelling levels at low pH (4.4). In contrast, their swelling levels at higher pH (7.4) were significantly enhanced. Higher swelling degree could be obtained at high pH. pH-responsive hydrogels are especially useful for various biological applications due to their unique feature of controlled swelling, biodegradability, biocompatibility, and fluid retention in their network structures. pH-responsive hydrogels, as intelligent systems, can be used in controlled-release drug delivery systems such as insulin delivery.

This work describes the oxidation of a catechol moiety to the corresponding quinone by using Mn(III)-based catalysts in the presence of an organic base. Two newly reported Mn(III)-Schiff base complexes were utilized for the oxidation of three different substrates, namely, 3,5-di tert-butyl catechol, 1,4-dihydroxy benzene and pyrocatechol, aerobically.

We intended to understand the role of a base for the above-mentioned oxidation process. Also, we were interested to monitor the progress of reaction using ¹H-NMR spectroscopy and to get more insight into the mechanistic path of the reaction.

The oxidation processes were studied in open air in acetonitrile or methanol solvent. The reaction mixture containing concerned substrate, catalyst, and base were stirred in open air and ¹H-NMR spectrum was recorded using the crude reaction mixture in different time intervals.

Interestingly, introduction of a base in the reaction mixture, enhanced the rate to a great extent for the first two substrates. This observation may provide an idea toward the rate determining step of the process. Notably, the third substrate, pyrocatechol, could not be oxidized by any of the two catalysts even with a base. The oxidation of 1,4-dihydroxy benzene may emphasize monodentate binding mode of the substrate. Each of the oxidation was monitored with the help of time dependent ¹H-NMR spectroscopy.

A mechanistic pathway has been proposed. The spectra obtained in different cases help to compare the efficiency of the catalysts with or without base. In the absence of the catalysts, triethylamine alone cannot complete the conversion in the stipulated time, which may establish the effectiveness of the catalysts via the base-assisted mechanism.

Condensation of 3-acetyl coumarin (1) with 2‐(4-methoxy- benzylidene)malononitrile (2) in ammonium acetate/acetic acid or absolute ethanol/piperidine affords pyridine (3) and chromen-2-one (4) derivatives, respectively.

In this study, the reaction of 3 with an electrophilic reagent, namely, formic acid, acetic anhydride and formamide afforded the pyridopyrimidinone and pyridine derivatives (6-9). Also, treatment of 3 with different aromatic aldehydes, carbon disulfide, NaN3/NH4Cl, 2-(4-methoxybenzylidene)malononitrile and acetophenone afforded pyridopyrimidinone, carbamodithioic acid, tetrazol-5-yl-chromen-2-one, 2H-chromen-2-one, and pyridine derivatives (10-14), respectively.

This study synthesized coumarins with antimicrobial activity and verified the structure and purity of the synthesized compounds using spectral data.

The new compounds were evaluated in vitro for their antimicrobial activity against gram-positive bacteria (Staphylococcus aureus, Methicillin-resistant Staphylococcus aureus) and gram-negative bacteria (Escherichia coli, Pseudomonas aeruginosa), in addition to fungus (Candida albicans). The investigated substances 3 and 14 presented good activity against MRSA, E. coli, P. aeruginosa and C. albicans, while compounds 9, 10a-c, 11, 12 and 13 exhibited good to moderate activity.

Lipid droplets (LDs) serve as primary storage sites for neutral lipids within cells and are crucial for lipid metabolism. Disorders affecting LDs can contribute to the pathogenesis of common metabolic diseases such as obesity and cancer, highlighting the importance of comprehending LD biology in health and disease contexts.

Fluorescence assays are commonly used for the detection and quantification of lipids in biological samples or lipid-rich environments. In this study, BODIPYs were synthesized and analyzed for structural confirmation. These compounds were subsequently evaluated for photophysical, electrochemical (cyclic voltammetry) and theoretical analysis, followed by live-cell imaging studies to confirm their affinity for intracellular lipid droplets.

BODIPYs have been identified as fluorogenic probes for live-cell imaging studies and found to serve as efficient and selective fluorescent substances for intracellular lipid droplets.

These BODIPYs, especially 2b, are valuable addition to the expanding toolkit for intracellular diagnostics, offering versatility and reliability across various cellular imaging applications.

The chiral triazole-oxazoline ligands are rarely reported.

The aim of the study was to synthsize some new chiral triazole-oxazoline ligands (S)-4-benzyl-2-(1-aryl-5-methyl-1H-1,2,3-triazole-4-yl)-4,5-dihydrooxazoline (5a-g).

The one-pot methods of oriented synthesis were adopted. This study provides a simple and effective method for the synthesis of new chiral triazole-oxazoline derivatives.

The some new chiral the triazole-oxazoline ligands (S)-4-benzyl-2-(1-aryl-5-methyl-1H-1,2,3-triazole-4-yl)-4,5-dihydrooxazoline (5a-g) were synthesized and the asymmetric Diels-Alder cyclization of 3-allyl-1,3-oxazolidin-2-ketone and 2-methyl-1,3-butadiene was catalyzed by PdCl2 using the synthesized (S)-4-triazole-oxazoline ligands.

Some new (S)-4-benzyl-2-(1-aryl-5-methyl-1H-1,2,3-triazole-4-yl)-4,5-dihydro-oxazoline was synthesized by corresponding N-[(S)-1-hydroxy-3-phenylpropan-2-yl]-1-aryl-5-methyl-1H-1,2,3-triazole-4-formamide, through one-pot oriented synthesis method. After preliminary evaluation, the chiral triazoline-oxazoline ligands, in which 1,2,3-triazole rings, like pyridine-type rings, chiral materials were saved and replace one oxazoline ring in the dioxazoline ligands for asymmetric catalytic reactions.