Synthesis of 3,5-disubstituted 1,2,4-oxadiazoles using ionic liquid-phase organic synthesis (IoLiPOS) methodology

New 3,5-disubstituted 1,2,4-oxadiazoles were synthesized in five steps by ionic liquid-phase organic synthesis (IoLiPOS) methodology. The strategy involved the preparation of amidoxime from the ionic liquid-phase bound arylnitrile. Addition of various carboxylic acid to the amidoxime produced the expected 3,5-disubstituted 1,2,4-oxadiazoles via the stable O-acyl amidoxime intermediate grafted on the ionic liquid-phase. The 1,2,4-oxadiazoles were easily cleaved by transesterification under mild reaction conditions in high purity with good overall yields. The structures of the intermediates in each step were verified by routine spectroscopic analysis (¹H, ¹³C NMR, and HRMS).     

(±)-trans,cis-4-Hydroxy-5,6-di-O-isopropylidenecyclohex-2-ene-1-one: synthesis and facile dimerization to decahydrodibenzofurans

An efficient synthesis of (±)-trans,cis-4-hydroxy-5,6-di-O-isopropylidenecyclohex-2-ene-1-one (3) has been developed from acetonide-protected meso-1,2-dihydrocatechol derivative 1 via photooxygenation, then Kornblum-DeLaMare rearrangement. The product is unstable unless its 4-hydroxy group is protected, as it undergoes facile dimerization in solution to a 1:1 mixture of diastereoisomeric decahydrodibenzofurans 8 and 9. A new synthesis of the dihydrocatechol 1 from 1,3-cyclohexadiene has also been developed.     

Traveling Wave Ion Mobility Mass Spectrometry Study of Low Generation Polyamidoamine Dendrimers

We reported the use of ion mobility (IM) combined with mass spectrometry (MS) as an analytical tool to investigate low generation polyamidoanine (PAMAM) dendrimers. This analytical approach has been employed to separate ions of defective structures with different charge state but exactly the same m/z value. Tandem mass spectrometry (MS/MS) after IM separation allowed a comprehensive structural characterization of defective dendrimers. In addition, IM was used to evaluate the collision cross-sections of ions of perfect dendrimers. They showed a good correlation with calculated collision cross-sections obtained by the trajectory method (TM) and were also consistent with dimensions reported by other established analytical methods.      

Intrinsic ratios of glucose,fructose, glycerol and ethanol <Superscript>13</Superscript>C/<Superscript>12</Superscript>C isotopic ratio determined by HPLC-<Emphasis Type="Italic">co</Emphasis>-IRMS: toward determining constants for wine authentication

High-performance liquid chromatography linked to isotope ratio mass spectrometry (HPLC-co-IRMS) via a Liquiface© interface has been used to simultaneously determine ¹³C isotope ratios of glucose (G), fructose (F), glycerol (Gly) and ethanol (Eth) in sweet and semi-sweet wines. The data has been used the study of wine authenticity. For this purpose, 20 authentic wines from various French production areas and various vintages have been analyzed after dilution in pure water from 20 to 200 times according to sugar content. If the ¹³C isotope ratios vary according to the production area and the vintage, it appears that internal ratios of ¹³C isotope ratios \(\left( {R_{^{13} C} } \right)\) of the four compounds studied can be considered as a constant. Thus, ratios of isotope ratios are found to be 1.00?±?0.04 and 1.02?±?0.08 for \(R_{^{13} C_{G/F} }\) and \(R_{^{13} C_{Gly/Eth} }\), respectively. Moreover, \(R_{^{13} C_{Eth/Sugar} }\) is found to be 1.15?±?0.10 and 1.16?±?0.08 for \(R_{^{13} C_{Gly/Sugar} }\). Additions of glucose, fructose and glycerol to a reference wine show a variation of the \(R_{^{13} C}\) value for a single product addition as low as 2.5 g/L^?1. Eighteen commercial wines and 17 concentrated musts have been analyzed. Three wine samples are suspicious as the \(R_{^{13} C}\) values are out of range indicating a sweetening treatment. Moreover, concentrated must analysis shows that ¹³C isotope ratio can be also used directly to determine the authenticity of the matrix.

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Figure HPLC-co-IRMS chromatogram of a diluted sweet wine.

     

Synthesis and glycosidase inhibitory activity of enantiopure polyhydroxylated octahydroindoles and decahydroquinolines, analogs to castanospermine

The synthesis of new enantiopure polyhydroxylated octahydroindoles and decahydroquinolines, analogs to castanospermine, via a double reductive amination of enantiopure cyclic ketoaldehyde, and their inhibitory activity against α- or β-d-glucosidases, α-d-mannosidase and α-l-fucosidase are described.     

Cucurbit[5]uril derivatives as oxygen carriers

ABSTRACT

Cucurbit[n]urils are rigid cage-molecules of pumpkin-like shape, made of n-glycoluril units, able to bind mainly neutral molecules and cations. In this work, we investigate the binding of three cucurbit[5]uril derivatives with dioxygen O₂ and show that one of them, namely per-hydroxylated cucurbit[5]uril, (OH)₁₀CB[5], is able to significantly bind dioxygen gas at physiological temperature, even in the presence of sodium chloride at the concentration of injectable solution in blood. As cucurbit[n]urils studied up to now reveal low toxicity, per-hydroxylated cucurbit[5]uril appears as a promising precursor to design a host able to transport O₂ in a haemoglobin substitute solution.     

Synthesis and Properties of Alkoxy‐ and Alkenyl‐Substituted Peralkylated Imidazolium Ionic Liquids

Novel peralkylated imidazolium ionic liquids bearing alkoxy and/or alkenyl side chains have been synthesized and studied. Different synthetic routes towards the imidazoles and the ionic liquids comprising bromide, iodide, methanesulfonate, bis(trifluoromethylsulfonyl)imide ([NTf₂]^?), and dicyanamide {[N(CN)₂]^?} as the anion were evaluated, and this led to a library of analogues, for which the melting points, viscosities, and electrochemical windows were determined. Incorporation of alkenyl moieties hindered solidification, except for cations with high symmetry. The alkoxy‐derivatized ionic liquids are often crystalline; however, room‐temperature ionic liquids (RTILs) were obtained with the weakly coordinating anions [NTf₂]^? and [N(CN)₂]^?. For the viscosities of the peralkylated RTILs, an opposite trend was found, that is, the alkoxy derivatives are less viscous than their alkenyl‐substituted analogues. Of the crystalline compounds, X‐ray diffraction data were recorded and related to their molecular properties. Upon alkoxy substitution, the electrochemical cathodic limit potential was found to be more positive, whereas the complete electrochemical window of the alkenyl‐substituted imidazolium salts was shifted to somewhat more positive potentials.     

A photoactivable probe for calcium binding proteins

Ca2+ as a signaling molecule carries information pivotal to cell life and death via its reversible interaction with a specific site in a protein. Although numerous Ca2+-dependent activities are known, the proteins responsible for some of these activities remain unidentified. We synthesized and characterized a photoreactive reagent, azido ruthenium (AzRu), which interacts specifically with Ca2+ binding proteins and strongly inhibits their Ca2+-dependent activities, regardless of their catalytic mechanisms or functional state as purified proteins, embedded in the membrane or in intact cells. As expected from a Ca2+ binding protein-specific reagent, AzRu had no effect on Ca2+-independent and Mg2+-dependent activities. Az103Ru covalently bound, and specifically labeled, known Ca2+ binding proteins. AzRu is a photoreactive reagent that provides an approach for identification of Ca2+ binding proteins, characterization of their binding sites, and exploration of new Ca2+-dependent processes.     

How 10 at% Al Addition in the Ti-V-Zr-Nb High-Entropy Alloy Changes Hydrogen Sorption Properties

Al_0.10Ti_0.30V_0.25Zr_0.10Nb_0.25 was prepared to evaluate the effect of 10% aluminum into the previously reported quaternary alloy, Ti_0.325V_0.275Zr_0.125Nb_0.275. The as-cast quinary alloy formed a single-phase body centered cubic solid solution and transformed into a body centered tetragonal after hydrogenation. The alloy had a storage capacity of 1.6 H/M (2.6 wt.%) with fast absorption kinetics at room temperature, reaching full capacity within the first 10 min. The major improvements of Al addition (10%) were related to the desorption and cycling properties of the material. The temperature for hydrogen release was significantly decreased by around 100 °C, and the quinary alloy showed superior cycling stability and higher reversible storage capacity than its quaternary counterpart, 94% and 85% of their respective initial capacity, after 20 hydrogenation cycles without phase decomposition.     

Comparison of available analytical methods to measure trans-octadecenoic acid isomeric profile and content by gas-liquid chromatography in milk fat

Accurate quantification of trans-fatty acids (TFAs) could be achieved by infrared spectroscopy or by gas-liquid chromatography (GLC). Accurate quantification by GLC should be achieved using specific highly polar capillary columns such as 100 m CP-Sil 88 or equivalent. A pre-fractionation of cis and trans-fatty acids could be performed by silver-ion thin-layer chromatography (Ag-TLC), silver-ion solid-phase extraction (Ag-SPE), or by high-performance liquid-chromatography (HPLC). A pre-fractionation step allows accurate determination of the isomeric profile but it is not essential to achieve quantification of total trans-18:1 isomers nor to determine the level of vaccenic (trans-11 18:1) acid in dairy fat. TFA content could also be calculated in milk fat based on the TAG profile determined by GLC. In this paper, different GLC methods suitable to measure the total of trans-18:1 isomers, vaccenic acid and trans-18:1 acid isomeric distribution in milk fat were compared. Pre-separation of cis- and trans-18:1 isomers by Ag-TLC followed by GLC analysis under optimal conditions was selected as the reference method. Results obtained using alternative methods including pre-separation by HPLC followed by GLC analysis, direct quantification by GLC or calculation from the triacylglycerol (TAG) profile were compared to data acquired using the reference method. Results showed that accurate quantification of total trans-18:1 isomers and vaccenic acid could be achieved by direct quantification by GLC under optimal chromatographic conditions. This method represents a very good alternative to Ag-TLC followed by GLC analysis. On the other hand, we showed that pre-fractionation of fatty acid methyl esters (FAMEs) by HPLC represents a good alternative to Ag-TLC, even if some minor isomers are not selectively purified using this procedure.