Search Results (44)

The problem of antibiotic resistance is one of the challenges that science and medicine face in the 21st century. Nucleoside analogs have already proven as antiviral and antitumor agents, and, currently, there are more and more reports on their antibacterial and antifungal activity. The substitution of an oxygen atom by a sulfur one leads to the emergence of unique properties. Here, we report the synthesis of eight new 4-thioanalogs of 5-substituted (5-alkyloxymethyl and 5-alkyltriazolylmethyl) derivatives of 2′-deoxyuridine and uridine, which were active against Mycobacterium tuberculosis and Gram-positive bacteria. The novel sulfur-containing nucleosides were synthesized via activation of the pyrimidine C4 position, followed by condensation with thioacetic acid and deblocking. To increase the solubility, oligoglycol carbonate depot forms were obtained via activation of the 3′-hydroxyl group using N,N’-carbonyldiimidazole and condensation with triethylene glycol. The highest inhibitory activity was demonstrated by 3′-triethylene glycol depot forms of 4-thio-5-undecyl- and 5-dodecyloxymethyl-2′-deoxyuridine (4a,b) against two strains of M. smegmatis. The most promising compounds were 5-[4-decyl-(1,2,3-triazol-1-yl)methyl]-4-thio-2′-deoxy- and ribouridine (3c,g) and 5-undecyloxymethyl 4-thiouridine (3e) active toward clinical M. intracellulare isolates. Overall, novel sulfur-containing nucleoside analogs were low toxic, demonstrated better inhibitory activity compared to their C4-oxo ones, and, thus, are promising compounds for the development of new antibacterial agents. Full article

Metal-free C(sp³)–S bond cleavage of thioethers was achieved using NCS as a critical additive. A wide range of arylmethyl thioethers were successfully transformed into aryl aldehydes with satisfactory yields in chloroform. Meanwhile, employing fluorobenzene as the solvent enables the selective formation of dithioacetals from arylmethyl thioethers, achieving moderate to good yields. Notably, dithioacetals were first prepared through a metal-free C(sp³)–S bond cleavage and subsequent thioacetalization process. Furthermore, these simple and efficient approaches also provide complementary strategies for accessing important aryl aldehydes and dithioacetals. Full article

The influence of sulfide (S²⁻) concentration on the corrosion resistance of Cr₃C₂-25(Ni20Cr) cermet coating on Al7075 (EN, AW-7075) substrate (Cr₃C₂-25(Ni20Cr)/Al7075) was investigated. The coating was produced by the cold-sprayed (CS) method. The Cr₃C₂-25(Ni20Cr)/Al7075 coatings were modified chemically in solutions containing thioacetic acid amide (TAA). The surface and microstructure of the specimens were both observed by a scanning electron microscope (SEM). The mechanical properties of the Cr₃C₂-25(Ni20Cr) coatings were characterized using microhardness (HV) measurements. The corrosion tests of the materials were carried out using the electrochemical method in a acidic chloride solution. The adsorbed (Me_mS_n)_ads layer effectively separates the Cr₃C₂-25(Ni20Cr)/Al7075 coating surface from contact with the aggressive corrosive environment. More than a twice lower value of corrosion rate (CW) was obtained for the Cr₃C₂-25(Ni20Cr)/Al7075 coating after exposure to the environment with 0.15 M TAA. Full article

A novel and controllable synthesis of thioacetals/thioketals and β-sulfanyl ketones mediated by the reaction of aldehyde/acetone with thiols has been developed. In this protocol, β-sulfanyl ketones can be generated without the prior preparation of α, β-unsaturated carbonyl compounds. A variety of thiols reacted with aldehyde/acetone and provided the corresponding thioacetals/thioketals and β-sulfanyl ketones in good to excellent yields, respectively. This protocol is operationally simple, mild, and atom-economical, providing controllable access to thioacetals/thioketals and thia-Michael addition products under mild conditions. Full article

Aryl and heteroaryl iodides have been efficiently converted into the corresponding thioacetates in cyclopentyl methyl ether (CPME), a green solvent, under Cu catalysis. The chemoselectivity of the reaction is mainly controlled by electronic factors, enabling the conversion of both electron-rich and electron-deficient substrates into the corresponding thioacetates in good to excellent yields. The products can be easily deprotected to the corresponding thiolates to carry out additional synthetic transformations in situ. Surprisingly, despite CPME’s relatively low dielectric constant, the reaction rate significantly increased when conducted under microwave irradiation conditions. This synthetic methodology exhibits a remarkable tolerance to functional groups, mild reaction conditions, and a wide substrate scope, utilizing a safe and inexpensive CuI pre-catalyst in the green solvent CPME. A non-aqueous workup allowing for the complete recovery of both catalyst and solvent makes this approach an environmentally sustainable protocol for C(sp²) sulfur functionalization. Additionally, the reaction shows selective cross-coupling with iodides in competition with chlorides and bromides, allowing its use in multistep syntheses. To demonstrate the potential of this methodology, it was applied to the high-yield synthesis of a photochromic dithienylethene, where a selective synthesis had not been reported before. Full article

The influence of yeast assimilable nitrogen (YAN) and elemental sulfur (S⁰) on the formation of volatile sulfur compounds (VSCs) during fermentation was investigated. Pinot noir fermentations were performed using Saccharomyces cerevisiae strain UCD522 or P1Y2 with an addition of 0, 5, or 15 µg/g elemental sulfur. H₂S production during fermentation was measured using lead acetate tubes and additional VSCs measured by GC-PFPD. The addition of S⁰ resulted in H₂S formation during alcoholic fermentation regardless of which yeast strain was used. H₂S production was greater in fermentations performed by UCD522 with increasing amounts of S⁰ resulting in increased production of H₂S. Higher S⁰ resulted in wines containing higher concentrations of methyl thioacetate and glutathione disulfide. Additional experiments examined the impact of nitrogen composition and S⁰. The addition of diammonium phosphate (DAP) resulted in an increase in H₂S formation during fermentation whereas the addition of amino acids did not, whether S⁰ was added or not. Fermentations where DAP and S⁰ were both added produced a higher concentration of H₂S compared to fermentations where S⁰ or DAP additions were made individually. VSCs in the wine were also impacted by the addition of nitrogen and/or S⁰ with the addition of S⁰ and nitrogen (DAP or amino acids) resulting in elevated concentrations of methyl thioacetate in the wines. Full article

Considering the biological and ecological importance of Cu–thiol interactions and the discrepancies in previous research, this study focuses on Cu interactions with biologically and ecologically relevant thiols: glutathione (GSH), L-cysteine (L-cys), 3-mercaptopropionic acid (MPA), and thioacetic acid (TAA) in aqueous solution. The addition of Cu(II) to a thiol-containing solution led to a rapid reduction of Cu(II) and the formation of a Cu(I)–thiol complex. The mechanism of Cu(II) reduction and Cu(I) complex formation as well as the kinetics of Cu(I) oxidation strongly depend on the structural properties of the individual thiols investigated. The reducing power of the investigated thiols can be summarized as follows: L-cys ≅ GSH > MPA > TAA. The reaction order, with respect to Cu(I) oxidation, also changes over the time of the reaction course. The deviation of the reaction kinetics from the first order with respect to Cu(I) in the later stages of the reaction course can be attributed to a Fenton-like reaction occurring under low thiol concentration conditions. At high Cu:thiol ratios, in the case of GSH, L-cys, and MPA, the early stage of the reaction course is characterized by high Cu(I) stability, most likely as a result of Cu(I) complexation by the thiols present in excess in the reaction mixture. Full article

The divergent reactivity of D-A cyclopropane, under PTC conditions, is herein reported. Thus, a ring-opening or a decyanation reaction can be achieved by reacting 2-arylcyclopropane-1,1-dicarbonitriles 1 with thioacetic acid in different reaction conditions. The use of solid Cs₂CO₃ leads unexpectedly to the synthesis of new D-A cyclopropane derivatives via a decyanation reaction, followed by diastereoselective acetylation, whereas the use of an aqueous solution of Cs₂CO₃ results in a typical ring-opening reaction with the formation of S-thiolate products. Therefore, the use of tailored reaction conditions allows one to obtain either cyclic or open-chain products in moderate to good yields. Full article

In this study, functional Pluronic F127 precursors were designed and synthesized for the preparation of thermosensitive hydrogels. Using linear Pluronic thioacetate and Pluronic multi-acrylate precursors, F127-based hydrogels were prepared through thioacetate deprotection-mediated Michael-type addition. The properties of these gels were compared to those obtained through free radical crosslinking of F127 diacrylate. Temperature was found to have a clear influence on gel swelling as a result of F127 thermoresponsiveness. The macromolecular architecture and functionality of the precursors were also optimized and characterized in terms of gelation kinetics and drug diffusion. In vitro tests were conducted on fibroblasts and endothelial cells to assess their response to cellular adhesion with Pluronic gels that were functionalized with an RGD peptide or pretreated with serum proteins to promote cell adhesion. This study provides a method for creating tailored hydrogels suitable for various biomedical applications, such as soft-tissue engineering, cell encapsulation, wound healing, and sustained delivery of therapeutic molecules. Full article

A series of poly(thiourethanes) (PTUs) from biobased monomers have been synthesized. Limonene and squalene were transformed into polyfunctional thiols by thiol-ene reaction with thioacetic acid and further saponification. They were then reacted in different proportions with hexamethylene diisocyanate (HDI) in the presence of a catalyst to prepare bio-based poly(thiourethane) vitrimer-like materials. The different functionalities of squalene and limonene thiols (six and two, respectively) allow for changing the characteristics of the final material by only varying their relative proportions in the reactive mixture. The proportions of thiol and isocyanate groups were stoichiometric in all the formulations tested. An acidic and a basic catalyst were tested in the preparation of the networked polymers. As the acidic catalyst, we selected dibutyltin dilaurate (DBTDL), and as the basic catalyst, a tetraphenylborate salt of 1,8-diazabicyclo(5.4.0)undec-7-ene (BGDBU), which has the advantage of only releasing the base at high temperatures. The materials obtained were characterized by thermogravimetry and thermomechanical analysis. The vitrimeric-like behavior was evaluated, and we could see that higher proportions of the limonene derivative in the formulations led to faster stress relaxation of the material. The use of the base catalyst led to a much shorter relaxation time. The materials obtained demonstrated good self-healing efficiency. Full article

This review describes the recent advances in photocatalyzed reactions to form new carbon–sulfur and carbon–selenium bonds. With a total of 136 references, of which 81 articles are presented, the authors introduce in five sections an updated picture of the state of the art in the light-promoted synthesis of organochalcogen compounds (from 2019 to present). The light-promoted synthesis of sulfides by direct sulfenylation of C–C π-bonds; synthesis of sulfones; the activation of C_sp2–N bond in the formation of C_sp2–S bonds; synthesis of thiol ester, thioether and thioacetal; and the synthesis of organoselenium compounds are discussed, with detailed reaction conditions and selected examples for each protocol. Full article

Mangrove actinomycetia have been proven to be one of the promising sources for discovering novel bioactive natural products. Quinomycins K (1) and L (2), two rare quinomycin-type octadepsipeptides without intra-peptide disulfide or thioacetal bridges, were investigated from the Maowei Sea mangrove-derived Streptomyces sp. B475. Their chemical structures, including the absolute configurations of their amino acids, were elucidated by a combination of NMR and tandem MS analysis, electronic circular dichroism (ECD) calculation, advanced Marfey’s method, and further unequivocally confirmed by the first total synthesis. The two compounds displayed no potent antibacterial activity against 37 bacterial pathogens and had no significant cytotoxic activity against H460 lung cancer cells. Full article

Many chemically synthesized xenobiotics can significantly inhibit the vitality of parasitic nematodes. However, there is yet too little research on the toxicity of such contaminating compounds toward nematodes. Compounds that are present in plants are able to inhibit the vitality of parasitic organisms as well. According to the results of our laboratory studies of toxicity, the following xenobiotics caused no decrease in the vitality of the larvae of Strongyloides papillosus and Haemonchus contortus: methanol, propan-2-ol, propylene glycol-1,2, octadecanol-1, 4-methyl-2-pen-tanol, 2-ethoxyethanol, butyl glycol, 2-pentanone, cyclopentanol, ortho-dimethylbenzene, dibutyl phthalate, succinic anhydride, 2-methylfuran, 2-methyl-5-nitroimidazole. Strong toxicity towards the nematode larvae was exerted by glutaraldehyde, 1,4-diethyl 2-methyl-3-oxobutanedioate, hexylamine, diethyl malonate, allyl acetoacetate, tert butyl carboxylic acid, butyl acrylate, 3-methyl-2-butanone, isobutyraldehyde, methyl acetoacetate, ethyl acetoacetate, ethyl pyruvate, 3-methylbutanal, cyclohexanol, cyclooctanone, phenol, pyrocatechin, resorcinol, naphthol-2, phenyl ether, piperonyl alcohol, 3-furoic acid, maleic anhydrid, 5-methylfurfural, thioacetic acid, butan-1-amine, dimethylformamide, 1-phenylethan-1-amine, 3-aminobenzoic acid. Widespread natural compounds (phytol, 3-hydroxy-2-butanone, maleic acid, oleic acid, hydroquinone, gallic acid-1-hydrate, taurine, 6-aminocaproic acid, glutamic acid, carnitine, ornithine monohydrochloride) had no negative effect on the larvae of S. papillosus and H. contortus. A powerful decrease in the vitality of nematode larvae was produced by 3,7-dimethyl-6-octenoic acid, isovaleric acid, glycolic acid, 2-oxopentanedioic acid, 2-methylbutanoic acid, anisole, 4-hydroxy-3-methoxybenzyl alcohol, furfuryl alcohol. The results of our studies allow us to consider 28 of the 62 compounds we studied as promising for further research on anti-nematode activity in manufacturing conditions. Full article

In a basic medium, 5-Mercapto-1,2,4-triazoles pass into the thiol form, allowing their transformation into sodium salts, which, in reaction with sodium monochloroacetate, lead to sodium 5-thioacetates of 1,2,4-triazoles-3,4-disubstituted. Sulfur derivatives converted to pivalic mixed anhydrides were used as active forms in the acylation of 6-amino penicillanic acid (6-AP) to obtain new semisynthetic penicillins. They contain in the molecule, together with the β-lactam ring, the nucleus 3-[(5-nitroindazol-1′-yl-methyl)]-4-aryl-5-mercapto-1,2,4-triazole, both contributing to an important antibacterial effect. The structure of the new antibiotics was confirmed by the results of elemental and spectral analysis (FT-IR, ¹H- and ¹³C-NMR). The synthetic penicillins were tested for toxicological action and antibacterial activity and the obtained results were close to those for amoxicillin, the reference drug. Full article

¹⁸F-labelled radiotracers are in high demand and play an important role for diagnostic imaging with positron emission tomography (PET). Challenges associated with the synthesis of the labelling precursors and the incorporation of [¹⁸F]fluoride with practical activity yields at batch scale are the main limitations for the development of new ¹⁸F-PET tracers. Herein, we report a high-yielding and robust synthetic method to access naked dibenzothiophenium salt precursors of complex PET tracers and their labelling with [¹⁸F]fluoride. C-S cross-coupling of biphenyl-2-thioacetate with aryl halides followed by sequential oxidation-cyclisation of the corresponding thioethers gives dibenzothiophenium salts in good to excellent yields. Labelling of neutral and electron-deficient substrates with [¹⁸F]fluoride is ultrarapid and occurs under mild conditions (1 min at 90 °C) with high activity yields. The method enables facile synthesis of complex and sensitive radiotracers, as exemplified by radiofluorination of three clinically relevant PET tracers [¹⁸F]UCB-J, [¹⁸F]AldoView and [¹⁸F]FNDP, and can accelerate the development and clinical translation of new ¹⁸F-radiopharmaceuticals. Full article