Redetermination of the structure of 2-amino-8-thia-1,5-diazaspiro[4,5]dec-1-en-5-ium chloride monohydrate

The reaction of β-(thiomorpholin-1-yl)propioamidoxime with tosyl chloride in CHCl3 in the presence of DIPEA when heated at 343 K for 8 h afforded the title hydrated salt, C7H14N3S+·Cl−·H2O, in 84% yield. This course of the tosylation reaction differs from the result of tosylation obtained for this substrate at room temperature, when only 2-amino-8-thia-1,5-diazaspiro[4.5]dec-1-ene-5-ammonium tosylate was isolated in 56% yield. The structure of the reaction product was established by physicochemical methods, spectroscopy, and X-ray diffraction. The single-crystal data demonstrated that the previously reported crystal structure of this compound [Kayukova et al. (2021). Chem. J. Kaz, 74, 21–31] had been refined in a wrong space group. In the extended structure, the chloride anions, water molecules and amine groups of the cations form two-periodic hydrogen-bonded networks with the fes topology.

DESIGN, CHARACTERIZATION AND ENHANCED BIOAVAILABILITY OF HYDROXYPROPYLCELLULOSE-BASED NOVEL BIOCONJUGATES FOR INCLUSION OF A FLUOROQUINOLONE ANTIBIOTIC – GEMIFLOXACIN

Polysaccharides are beneficially used as drug carriers via prodrug formation and offer a mechanism for better effectiveness and delivery of the drug. The unique geometry of hydroxypropylcellulose (HPC), a polysaccharide, allows the attachment of drug molecules with a higher degree of substitution. Therefore, HPC-gemifloxacin conjugates, i.e., macromolecular prodrugs, were synthesized using acylation reagents, i.e., tosyl chloride and carbonyldiimidazole using N,N-dimethylacetamide as a solvent. The reactions were carried out at 80 °C under stirring for 24 h in inert environment. This strategy of reaction appeared efficient to obtain a high degree of drug substitution (DS = 0.42-1.34) on the polymer parent chain, as calculated by UV-visible spectrophotometry after hydrolysis of the samples. The method provides high efficacy as product yields were high (71-76%). Macromolecular prodrugs with different DS of gemifloxacin (GEM) designed were found soluble in organic solvents. The pharmacokinetic studies showed that the t1/2 and tmax values of GEM from HPC-GEM conjugate were considerably higher, which indicates improved bioavailability of the drug after conjugate formation.

Occurrence and Levels of Biogenic Amines in Beers Produced by Different Methods

The concentration of biogenic amines (BAs) in beer depends, among other factors, on the activity of microorganisms, in particular lactic acid bacteria. In this work an analytical method based on derivatization with tosyl chloride and high-performance liquid chromatography-tandem mass spectrometry (HPLC-MS/MS) was used to determine 17 BAs in samples of commercially available beers, and to monitor the changes in concentration of several BAs throughout the fermentation process. In some of the analysed samples the concentration of BAs exceeded the safety threshold for consumers. During the fermentation stage of home-brewing of ale the concentration of spermine in the wort increased until the end of the stormy fermentation, to then drop below the initial concentration at the end of fermentation, and below the LOQ after refermentation. The results of the study indicate that monitoring the total content of BAs is required due to the potential risk to human health.

Catalytic and co-ordination chemistry of enolate oxazoline K2-N,O-ligands to group 9 & 11 transition metals

The co-ordination chemistry and resulting catalytic potential of Group 9 and 11 transition metal centered complexes with the 2-acylmethyl-2-oxazoline skeleton are detailed. Each of the synthesized ligand species were treated with either a Copper (II) or Cobalt (II) salt to promote co-ordination, in all cases deprotonation of the ligand occurred. These complexes have, thereafter, been examined by infrared spectroscopy (IR), UV-Visible spectroscopy (UV-Vis), mass spectrometry (MS), cyclic voltammetry (CV), combustion analysis (EA) and x-ray diffraction and probed for their potential redox properties. In the case of Cu(II) chelated complexes, no desirable redox behaviour was observed. Although, with respect to Co(II) complexes, one complex displayed favourable redox potential. The redox active species have been shown to effectively catalyze the polymerization of methyl methacrylate with tosyl chloride as an initiator, through an ATRP-like mechanism. Work within also reflects preliminary co-ordination to Iridium and Rhodium metal centers. Successfully synthesized Iridium complexes have been tested with respect to their oxidative properties. Positive results have been observed in their ability to perform oxidative addition with both HSnPh3 and MeI. Both small molecule species have been effectively added to an Ir(I) complex, formally changing its oxidation state to Ir(III).

Catalytic and co-ordination chemistry of enolate oxazoline K2-N,O-ligands to group 9 & 11 transition metals

The co-ordination chemistry and resulting catalytic potential of Group 9 and 11 transition metal centered complexes with the 2-acylmethyl-2-oxazoline skeleton are detailed. Each of the synthesized ligand species were treated with either a Copper (II) or Cobalt (II) salt to promote co-ordination, in all cases deprotonation of the ligand occurred. These complexes have, thereafter, been examined by infrared spectroscopy (IR), UV-Visible spectroscopy (UV-Vis), mass spectrometry (MS), cyclic voltammetry (CV), combustion analysis (EA) and x-ray diffraction and probed for their potential redox properties. In the case of Cu(II) chelated complexes, no desirable redox behaviour was observed. Although, with respect to Co(II) complexes, one complex displayed favourable redox potential. The redox active species have been shown to effectively catalyze the polymerization of methyl methacrylate with tosyl chloride as an initiator, through an ATRP-like mechanism. Work within also reflects preliminary co-ordination to Iridium and Rhodium metal centers. Successfully synthesized Iridium complexes have been tested with respect to their oxidative properties. Positive results have been observed in their ability to perform oxidative addition with both HSnPh3 and MeI. Both small molecule species have been effectively added to an Ir(I) complex, formally changing its oxidation state to Ir(III).

Nucleophilic Displacement Reaction on Tosyl Cellulose by L-Methionine to the Synthesis of Novel Water-Soluble Cellulose Derivative and Its Antibacterial Activity

A novel ampholytic cellulose derivative, cellulose-L-methionine, has been synthesized by means of an esterification reaction of microcrystalline cellulose with tosyl chloride (p-TsCl) in DMAc/LiCl (8%) at 8°C that was followed by nucleophilic displacement (SN) of the tosyl group by the L-methionine amino acid. The resulting structure of cellulose-L-methionine has been characterized by elemental analysis (CHNSO), Fourier-transform infrared spectroscopy (FTIR), proton nuclear magnetic resonance (1H-NMR), and scanning electron microscopy (SEM). The antibacterial activity of the synthesized product was screened against Gram-positive and Gram-negative microbial strains such as Staphylococcus aureus, Escherichia coli, and Pseudomonas aeruginosa, by the agar well diffusion method, and compared with commercial antibiotics such as ampicillin and chloramphenicol. It was found that antibacterial experiment revealed excellent antibacterial activity of the cellulose-methionine with respect to a minimal inhibitory concentration (MIC) reference.

Catalytic, Regioselective Sulfonylation of Carbohydrates with Dibutyltin Oxide under Solvent-Free Conditions

A simple approach was developed for the solvent-free regioselective functionalization of carbohydrate polyols with 4-toluesulfonyl (tosyl) group, allowing the easy and quick activation of a saccharide site with a tosylate leaving group. The method is based on the use of catalytic dibutyltin oxide and tetrabuylammonium bromide (TBAB), and a moderate excess of N,N-diisopropylethyl amine (DIPEA) and tosyl chloride (TsCl), leading to the selective functionalization at 75 °C of a secondary equatorial hydroxy function flanked by an axial one in a pyranoside. The procedure is endowed with several advantages, such as the use of cheap reagents, experimental simplicity, and the need for reduced reaction times in comparison with other known approaches.

Comparative Studies on Regioselectivity of α- and β-Linked Glucan Tosylation

Alpha- and beta-linked 1,3-glucans have been subjected to conversion with p-toluenesulfonic acid (tosyl) chloride and triethylamine under homogeneous reaction conditions in N,N-dimethyl acetamide/LiCl. Samples with a degree of substitution of tosyl groups (DSTs) of up to 1.91 were prepared by applying 5 mol reagent per mole repeating unit. Hence, the reactivity of α-1,3-glucan is comparable with cellulose and starch, while the β-1,3-linked glucan curdlan is less reactive. The samples dissolve in aprotic dipolar media independent of the DSTs and possess a solubility in less polar solvents that depends on the DSTs. NMR studies on the tosyl glucans and of the peracylated derivatives showed a preferred tosylation of position 2 of the repeating unit. However, the selectivity is less pronounced compared with starch. It could be concluded that the α-configurated glycosidic bond directs tosyl groups towards position 2.