Condensation of aldehydes and ketones

The alkaline condensation of β-aceto-and β-propionaphthalenes with furfural has given, respectively, 2-(α-furfuryl)-1, 3-di(β-naphthoyl)-propane and 3-(α-furyl)-2,4-di(β-naphthoyl)pentane; both δ-diketones have also been obtained by the Michael condensation. Under more severe conditions, two molecules of furfural condense with three molecules of β-acetonaphthalene to form 2, 4-di(α-furyl)-1, 3, 5-tri(β-naphthoyl)pentane. Under similar conditions, benzaldehyde exhibits only a feeble capacity for triketone condensation with β-acetonaphthalene. The condensation of β-propionaphthalene with furfural has given the new compound furylidenepropionaphthalene. It has been shown that both under the conditions of the improved Chichibabin pyridine synthesis and under the conditions of the Leuckhardt reaction, 3-(α-furyl)-1, 3-di(β-naphthoyl)propane gives 4-(α-furyl)-2, 6-di(β-naphthyl)pyridine.     

Cycloascauloside b from <Emphasis Type="Italic">Astragalus caucasicus</Emphasis>

The structure of a new cycloartane glycoside isolated from leaves of Astragalus caucasicus Pall. (Leguminosae) was elucidated using chemical transformations and spectral data. Cycloascauloside B is 20R, 25-epoxy-24S-cycloartan-3β,6α,16β,24-tetraol 3-O-[α-L-rhamnopyranosyl-(1å2)]-β-D-glucopyranoside.     

Modeling of the electronic,optoelectronics, photonic and thermodynamics properties of 1,4-bis(3-carboxyl-3-oxo-prop-1-enyl) benzene molecule

The modeling of the molecule 1,4-bis(3-carboxyl-3-oxo-prop-1-enyl) benzene has been carried out to study the electronic, optoelectronics, photonic and thermodynamics properties using Hartree–Fock, density functional theory (B3LYP) and MP2 (Möller–Plesset perturbation theory second-order) with the 6-31G and 6-31+G** basis sets. The dipole moment (µ), polarizability (〈α〉), first hyperpolarizability (β _mol), dielectric constant (ε), electric susceptibility (χ), refractive index (η) and thermodynamics properties of this molecule have been calculated using the same level of theory. The small values of ε, and LUMO–HOMO energy gap, and the high values of χ, η, MR, 〈α〉 and (β _mol) show that the molecule has very good electronic, optoelectronic and photonic applications. The results of this study show that this molecule is an interesting pi-conjugated molecule whose electronic structure and properties can be regulated over a wide range by variation in backbone structure, by side group substitution, and through intramolecular hydrogen bonding.     

Alternate solutions for two particular third order kinetic rate laws

Alternate solutions to third order rate law expressions which are first order in one reactant and second order in another for the generalized reaction \({{aA}+{bB}\mathop \rightarrow \limits^{k_A }{P}}\) with a limiting reactant and for simple cubic autocatalysis \({{A}+{ 2B}\mathop \rightarrow \limits^{k_A }{3B}}\) are presented and discussed. These solutions are expressed in terms of the Lambert function W[x] with argument x(t) = α exp(α ? β t), where α and β are empirical parameters. These expressions permit the concentrations of the reactant species to be explicitly represented as dependent functions of time. For the generalized reaction, the solution involves considering exactly which species is limiting, so that the correct branch of the Lambert function can be determined. For simple cubic autocatalysis, the solution is shown to be consistent with the characteristics associated with clock reactions. An exact expression for the “induction time” associated with a clock reaction described by this mechanism is also derived.     

Glycosylation of panaxadiol

Glycosylation of 3β,12β-dihydroxy-20R,25-epoxydammarane (panaxadiol) (1) under Koenigs–Knorr, Helferich, and ortho-ester reaction conditions was studied. Condensation of panaxadiol and 2,3,4,6-tetra-O-acetyl-α-D-glucopyranosylbromide (2) in the presence of silver oxide and 4-Å molecular sieves in dichloroethane gave a mixture of acetylated panaxadiol 3- and 12-O-β-D-glucopyranosides (3:1 ratio). Reaction of diol 1 and D-glucose tert-butylorthoacetate (3) in the presence of 2,4,6-collidinium perchlorate in chlorobenzene resulted in regioselective formation of panaxadiol 12-O-β-D-glucopyranoside tetraacetate. Reaction of equimolar amounts of 1 and glycosyl donor 2 in the presence of Hg(II) cyanide in nitromethane at 90°C was accompanied by opening of the tetrahydropyran ring and gave 3β,12β,25-trihydroxydammar20(22)E-ene 12-O-β-D-glucopyranoside tetraacetate. Panaxadiol 3- and 12-O-β-D-glucopyranosides and 3β,12β,25-trihydroxydammar-20(22)E-ene 12-O-β-D-glucopyranoside tetraacetate were synthesized for the first time.     

Thio-click approach to the synthesis of stable glycomimetics

Carbon-sulfur-bridged glycomimetics were prepared by free radical hydrothiolation of the exocyclic double bond of unsaturated sugars. Reaction between benzoyl-substituted pyranoid-exoglycal and a range of thiols including peptide, 1-thioglycerol and 1-thiosugar derivatives gave β-D-configured carbon-sulfur-linked glycoconjugates with full stereoselectivity. Addition of a panel of thiols to a 3-exomethylene-glucofuranose derivative also proceeded in a stereoselective manner and afforded a series of D-allo-configured 3-deoxy-3-C-S-bridged glycoconjugates.     

Synthetic transformations of isoquinoline alkaloids. Synthesis of 1-halo derivatives of <Emphasis Type="Italic">endo</Emphasis>-ethenotetrahydrothebaine and their behavior in the heck reaction

Bromination of endo-ethenotetrahydrothebaine derivatives having a pyrrolidine ring fused at the C⁷-C⁸ bond, namely 1′-substituted 4,5α-epoxy-6α,14-etheno-3,6-dimethoxy-17-methyl-2′,5′,7β,8β-tetrahydro-1′H-14α-pyrrolo[3′,4′:7,8]morphinan-2′,5′-diones, 1′-aryl-4,5α-epoxy-6α,14-etheno-3,6-dimethoxy-17-methyl-2′,5′,7β,8β-tetrahydro-1′H-14α-pyrrolo[3′,4′:7,8]morphinans, and 4,5α-epoxy-6α,14-etheno-2′α-hydroxy-3,6-dimethoxy-17-methyl-1′-phenyl-2′,5′,7β,8β-tetrahydro-1′H-14α-pyrrolo[3′,4′:7,8]morpphinan-5′-one, with molecular bromine in formic acid smoothly afforded the corresponding 1-bromo derivatives. Iodination of 4,5α-epoxy-6α,14-etheno-3,6-dimethoxy-17-methyl-1′-phenyl-2′,5′,7β,8β-tetrahydro-1′H-14α-pyrrolo[3′,4′:7,8]-4,5α-epoxy-6α,14-etheno-3,6-dimethoxy-17-methyl-1′-phenyl-2′,5′,7β,8β-tetrahydro-1′H-14α-pyrrolo[3′,4′:7,8]-morphinan-2′,5′-dione with iodine(I) chloride gave 4,5α-epoxy-6α,14-etheno-1-iodo-3,6-dimethoxy-17-methyl-1′-phenyl-2′,5′,7β,8β-tetrahydro-1′H-14α-pyrrolo[3′,4′:7,8]morphinan-2′,5′-dione. The resulting 1-halo derivatives were brought into the Heck reaction with acrylic acid esters to obtain 1-[(E)-2-(alkoxycarbonyl)ethenyl]-substituted compounds. Demethylation of the 6-methoxy group in 1-bromo-endo-ethenotetrahydrothebaines was accomplished using boron(III) bromide in chloroform.     

Synthesis and structure investigation of Co(III) complex salts with the perrhenate anion

Complex salts of the composition [Co(NH₃)₆](ReO₄)₃·2H₂O (I), [Co(en)₃](ReO₄)₃ (II), [Co(NH₃)₅H₂O](ReO₄)₃·2H₂O (III), and [Co(NH₃)₅Cl](ReO₄)₂·0.5H₂O (IV) are obtained. Their crystal structures are determined by single crystal XRD. Crystallographic characteristics: (I) a = 9.9797(3) Å, b = 12.6994(3) Å, c = 14.7415(4) Å, β = 102.870(1)°, C2/c space group; (II) a = 8.0615(3) Å, b = 8.4483(4) Å c = 8.8267(4) Å, α = 61.923(2)°, β = 89.552(2)°, γ = 72.295(2)°, P1 space group; (III) a = 8.0086(4) Å, b = 12.9839(6) Å, c = 17.5122(7) Å, β=91.858(1)°, P2₁/n space group; (IV) a = 14.9446(3) Å, b = 14.6562(4) Å, c = 12.2434(4) Å, Cmc2₁ space group.     

Composition of essential oils of four <Emphasis Type="Italic">Hedychium</Emphasis>species from Vietnam

Background

Vietnam is a country blessed with many medicinal plants widely used as food and for medicinal purposes, and they contain a host of active substances that contribute to health. However, the analysis of chemical constituents of these plant species has not been subject of literature discussion.

Results

In this study, the chemical compositions of essential oils of four Hedychium species, obtained by hydrodistillation, were determined by means of gas chromatography-flame ionization detector (GC-FID) and gas chromatography–mass spectrometry (GC-MS) techniques. Individually, α-pinene (52.5%) and β-pinene (31.8%) were present in the leaf oil of Hedychium stenopetalum Lodd., while linalool (45.2%), (E)-nerolidol (8.7%) and α-pinene (5.0%) were identified in the root. The leaf of Hedychium coronarium J. König was characterized by α-pinene (20.0%), linalool (15.8%), 1,8-cineole (10.7%), α-pinene (10.1%) and α-terpineol (8.6%); while α-pinene (23.6%), α-humulene (17.1%) and β-caryophyllene (13.0%) were identified in the root. Hedychium flavum Roxb., gave oil whose major compounds were α-pinene (22.5%), α-humulene (15.7%) and β-caryophyllene (10.4%) in the leaf; α-humulene (18.9%), β-caryophyllene (11.8%) and α-pinene (11.2%) in the stem, as well as α-pinene (21.8%), linalool (17.5%) and 1,8-cineole (13.5%) in the root. The main constituents of Hedychium ellipticum Buch.-Ham. ex Smith were (E)-nerolidol (15.9%), α-pinene (11.8%) and bornyl acetate (9.2%) in the leaf with 1,8-cineole (40.8%), α-pinene (18.3%) and α-pinene (11.0%) occurring in the root.

Conclusions

Ubiquitous monoterpenes and sesquiterpenes were identified as characteristic markers for Hedychium species. This work is of great importance for the evaluation of Hedychium essential oils grown in Vietnam.

     

Structure Studies of the Extracellular Polysaccharide from <Emphasis Type="Italic">Trichoderma</Emphasis> sp. KK19L1 and Its Antitumor Effect via Cell Cycle Arrest and Apoptosis

An extracellular polysaccharide TP1A was purified from the fermented broth of Trichoderma sp. KK19L1 by combination of Q Sepharose fast flow and Sephacryl S-300 chromatography. TP1A was composed of Man, Gal, and Glc in a molar ratio of about 3.0:5.1:8.1. The molar mass of TP1A was about 40.0 kDa. Methylation and NMR analysis indicated that the probable structure of TP1A was [→4,6)-α-D-Glcp(1→6)-β-D-Galf(1→6)-β-D-Galf(1→2,6)-β-D-Galf(1→2,6)-β-D-Galf(1→2,6)-β-D-Galf(1→2,6)-α-D-Manp(1→2,6)-α-D-Manp(1→] with [α-D-Glcp(1→] and [α-D-Manp(1→6)-α-D-Glcp(1→6)-α-D-Glcp(1→] as branches. The antitumor study showed that TP1A was able to inhibit the cell viability of HeLa and MCF-7 cells. TP1A could arrest HeLa cells in G2/M phase and induce HeLa cell apoptosis. These findings suggest that fungal polysaccharides could be a potential source for antitumor agents.     

Synthesis of β-Lactam and Anomalous Minor Products in the (<Emphasis Type="Italic">i</Emphasis>-Pr)<Subscript>2</Subscript>NEt-Promoted Reaction of <Emphasis Type="Italic">N</Emphasis>-Chloroglycine Methyl Ester Derivative with Dichloroacetyl Chloride

Apart from the expected [2 + 2]-cycloaddition product, the reaction of N-chloro-N-(2-methoxy-2-oxoethyl)-β-alanine methyl ester with dichloroacetyl chloride in the presence of ethyl(diisopropyl)amine gave minor N-(1,2-dichloro-2-oxoethyl)-β-alanine methyl ester and (3E)-1,1,1-trichloro-4-(diisopropylamino)- but-3-en-2-one.     

Temperature-dependent <Emphasis Type="Italic">β</Emphasis>-crystal growth in isotactic polypropylene with <Emphasis Type="Italic">β</Emphasis>-nucleating agent after shear flow

In our current work, the effect of the shear temperature on the growth of β-crystal in isotactic polypropylene (iPP) with β-nucleating agent is investigated by means of in situ two-dimensional wide-angle X-ray diffraction (2D-WAXD). At low shear temperatures, the formed shear-induced oriented precursors are hard to relax back to random coiled state due to the weak mobility of molecular chains. Therefore, plenty of oriented α-crystals are induced by shear-induced oriented precursors, while β-crystal is greatly depressed. As the shear temperature increases, oriented β-crystal gradually increases along with the decrease of α-crystal. It is deduced that the shear temperature at which the content of β-crystal increases to the (maximum) value found in quiescent crystallization is almost the same as that at which the accelerating effect of flow on crystallization kinetics is completely erased. Our work manifests its significance in regulating β-crystal and thus in the structure and property manipulation of iPP.     

Kinetics and mechanism of benzyl <Emphasis Type="Italic">para</Emphasis>-chlorophenyl ketone oxidation

The oxidation of benzyl para-chlorophenyl ketone in chlorobenzene at 100°C occurs through the formation of short chains. Non-peroxide reaction products (1-(4-chlorophenyl)-2-hydroxy-2-phenyl-1-ethanone, para-chlorobenzyl, benzaldehyde, and para-chlorobenzoic acid) are formed not only by the transformation of hydroperoxide (1-(4-chlorophenyl)-2-hydroxy-2-phenyl-1-ethanone) but also (or solely) through the recombination of α-ketoperoxyl radicals with or without chain termination. α-Hydroperoxide decomposes predominantly through a heterolytic route to form para-chlorobenzoic acid and benzaldehyde. Benzaldehyde and 1-(4-chlorophenyl)-2-hydroxy-2-phenyl-1-ethanone undergo radical chain oxidation in the reaction medium to form benzoic acid (benzaldehyde), para-chlorobenzyl, and benzoic and para-chlorobenzoic acids (1-(4-chlorophenyl)-2-hydroxy-2-phenyl-1-ethanone). The homolytic decomposition of α-hydroperoxy ketone and α-hydroxy-α-hydroperoxy ketone causes the self-acceleration of the process and affords 1-(4-chlorophenyl)-2-hydroxy-2-phenyl-1-ethanone or, to a lesser extent, benzaldehyde and para-chlorobenzoic acid (α-hydroperoxy ketone). para-Chlorobenzoic acid substantially accelerates the heterolytic decomposition of α-hydroxy-α-hydroperoxy ketone and the oxidation of benzyl para-chlorophenyl ketone with peroxy acids to ester according to the Baeyer-Villiger mechanism. The rate constants of the main steps of the process and kinetic parameters are calculated by solving the inverse kinetic problem.     

Analogs of ecdysteroids with a tetrasubstituted Δ<Superscript>8,14</Superscript>-bond

By hydrogenation of (20R,22R)-6α,14α,25-trihydroxy-and (20R,22R)-6β,14α,25-trihydroxy-2,3:20,22-bis(isopropylidenedioxy)-5α-cholest-7-enes on a catalyst (Raney nickel) the corresponding (5α,6α)-and (5β,6β)-epimers of previously unknown Δ^8,14-6-hydroxy derivatives of ecdysteroids were synthesized.     

New derivatives of 4-quinaldinol

The reactions of 1, 1, 3-trichloro-1-propene and also 1, 1, 1-trichloro-2-propene with acetoacetic ester gave α-(γ, γ-dichlorallyl)acetoacetic ester (I). In the reactions with aniline and o- and p-toluidines, the corresponding α-(γ, γ-dichloroallyl)-β-arylamino-crotonic esters were produced, thermal cyclization of which gave 2-methyl-3-(γ, γ-dichloroallyl)-4-hydroxyquinoline (II) and its 6CH₃- (III) and 8CH₃- (IV) homologs. With phosphorus oxychloride, II–IV gave the corresponding 4-chloro-substituted quinolines (V–VII); with concentrated sulfuric acid, II–VII were converted into the corresponding β-quinolinylpropionic acids VIII–XIII.     

New Insights on Non-Enzymatic Oxidation of Ganglioside GM1 Using Mass Spectrometry

Gangliosides are acidic glycosphingolipids that are present in cell membranes and lipid raft domains, being particularly abundant in central nervous systems. They participate in modulating cell membrane properties, cell–cell recognition, cell regulation, and signaling. Disturbance in ganglioside metabolism has been correlated with the development of diseases, such as neurodegenerative diseases, and in inflammation. Both conditions are associated with an increased production of reactive oxidation species (ROS) that can induce changes in the structure of biomolecules, including lipids, leading to the loss or modification of their function. Oxidized phospholipids are usually involved in chronic diseases and inflammation. However, knowledge regarding oxidation of gangliosides is scarce. In order to evaluate the effect of ROS in gangliosides, an in vitro biomimetic model system was used to study the susceptibility of GM1 (Neu5Acα2-3(Galβ1-3GalNAcβ1-4)Galβ1-4Glcβ1Cer) to undergo oxidative modifications. Oxidation of GM1 under Fenton reaction conditions was monitored using high resolution electrospray ionization-mass spectrometry (ESI-MS) and tandem mass spectrometry (ESI-MS/MS). Upon oxidation, GM1 underwent oxidative cleavages in the carbohydrate chain, leading to the formation of other gangliosides GM2 (GalNAcβ1-4Gal(Neu5Acα2-3)1-4Glcβ1Cer), GM3 (Neu5Acα2-3Galβ1-4Glcβ1Cer), asialo-GM1 (Galβ1-3GalNAcβ1-4Galβ1-4Glcβ1Cer), asialo-GM2 (GalNAcβ1-4Galβ1-4Glcβ1Cer), of the small glycolipids lactosylceramide (LacCer), glucosylceramide (GlcCer), and of ceramide (Cer). In addition, oxygenated GM1 and GM2 (as keto and hydroxy derivatives), glycans, oxidized glycans, and oxidized ceramides were also identified. Nonenzymatic oxidation of GM1 under oxidative stress contributes to the generation of other gangliosides that may participate in the imbalance of gangliosides metabolism in vivo, through uncontrolled enzymatic pathways and, consequently, play some role in neurodegenerative processes.

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Graphical Abstract ?

     

Researches ok heterocyclic rings containing nitrogen and sulfur II. Orotylamino acids,their esters,and salts of orotic acid with amines

Esters of orotylamino acid are synthesized by reacting orotyl chloride with glycine andα- andβ-alanine esters. Orotylamino acids are prepared by reducing the benzyl ester of orotylglycine, or by reacting orotyl chloride with sodium salts of amino acids. A series of salts of orotic acid are prepared by reacting orotic acid with amines.     

Molecular dynamic studies of amyloid-beta interactions with curcumin and Cu<Superscript>2+</Superscript> ions

Amyloid-beta (Aβ) peptide readily forms aggregates that are associated with Alzheimer’s disease. Transition metals play a key role in this process. Recently, it has been shown that curcumin (CUA), a polyphenolic phytochemical, inhibits the aggregation of Aβ peptide. However, interactions of Aβ peptide with metal ions or CUA are not entirely clear. In this work, molecular dynamics (MD) simulations were carried out to clear the nature of interactions between the 42-residue Aβ peptide (Aβ-42) and Cu²⁺ ions and CUA. Altogether nine different models were investigated, and more than 2 µs of the simulation data were analyzed. The models represent the possible modes of arrangement between Aβ-42 and Cu²⁺ ions and CUA, respectively, and were used to shed light on the Aβ-42 conformational behavior in the presence of Cu²⁺ ions and CUA molecules. Obtained data clearly showed that the presence of a CUA molecule or a higher concentration of copper ions significantly affect the conformational behavior of Aβ-42. Calculations showed that the change of the His13 protonation state (Aβ(H13δ)-Cu²⁺, Aβ(H13δ)-Cu²⁺ -CUA models) leads to higher occurrence of the Asp23-Lys28 salt bridge. Analyzes of trajectories revealed that C-terminal β-sheet structures occurred significantly less frequently, and CUA promoted the stabilization of the α-helical structure. Further, calculations of the Aβ-42 complex with CUA and Cu²⁺ ions showed that CUA can chelate the Cu²⁺ ion and directly interact with Aβ, which may explain why CUA acts as an inhibitor of Aβ aggregation.     

Enantioseparation of Hydrobenzoin and Structurally Related Compounds on <Emphasis Type="Italic">β</Emphasis>-Cyclodextrin and Hydroxypropyl-<Emphasis Type="Italic">β</Emphasis>-cyclodextrin Bonded Chiral Stationary Phases

A β-cyclodextrin (β-CD) and a hydroxypropyl-β-cyclodextrin (HP-β-CD) bonded chiral stationary phase (CSP) were prepared. Comparative evaluations of these two CSPs for the enantioseparation of hydrobenzoin, benzoin and α-phenethyl alcohol by reversed-phase liquid chromatography were presented. The effects of buffer composition in the mobile phase on the retention and enantioseparation were investigated. The borate buffer had a significant influence on the retention and enantioseparation of hydrobenzoin. Linear solvent strength retention model was used to fit the chromatographic data. Good linearity existed between the logarithm of retention factor (k) and the volume fraction of organic modifier (φ). Another retention model, stoichiometric displacement theory for retention, was also tried to fit the chromatographic data. The results showed that not only acetonitrile, but also water molecules participated in the displacing process of the solute.     

Bioactive compounds from <Emphasis Type="Italic">Smilax excelsa</Emphasis> L.

Phytochemical investigation of EtOAc extract of Smilax excelsa has led to isolation and structure elucidation of five compounds. The structures of these compounds are established by different spectroscopic techniques including 1D and 2D-NMR, HRMS and ECD spectroscopy. The compounds were: solanesol (1), violasterol A (2), trans-resveratrol (3), 5-O-caffeoylshikimic acid (4) and 6-O-caffeoyl-β-d-fructofuranosyl-(2-1)-α-d-glucopyranoside (5). The configuration of compound 2 was established by electronic circular dichroism (ECD) spectroscopy. Meanwhile the cytotoxicity and antibacterial activity of the compounds were evaluated by MTT and MIC assays. Compounds 1 and 2 showed promising inhibition on MCF-7 cell line with IC₅₀ of 161.6 and 190.0 µM, respectively. Also compounds 2 and 3 illustrated activity against Staphylococcus aureus with MIC values of 142.5 and 136.9 µM, respectively.