Sulfato groups capping one or two pairs of adjacent glucose units in methylated cyclodextrin (CD) derivatives have been found to undergo regioselective opening with various nucleophiles; the reported methodology opens the way to the efficient synthesis of tridifferentiated α- and β-cyclodextrins that constitute key starting materials for the preparation of ...

A stereoselective synthesis of (-)-1-epi-ventiloquinone L and (+)-ventiloquinone L, the monomeric unit of cardinalin 3 has been described. The synthesis is completed in 7 steps with 10.5% and 13% overall yields for (-)-1-epi-ventiloquinone L and (+)-ventiloquinone L respectively. The key steps involve Dötz benzannulation of carbene with alkyne to give ...

Ahead of the PAC: Polycyclic aromatic compounds (PACs) can be easily accessed by the combination of Suzuki-Miyaura cross-coupling and a [Rh(2) (OAc)(4) ]-catalyzed carbene reaction using easily available bis(N-tosylhydrazone)s as intermediates (see scheme; Ts=4-toluenesulfonyl).

A brilliant debut! Cinchona thioureas have been reported for the first time as catalysts in the area of asymmetric oxidations. They efficiently promote an unprecedented highly enantioselective epoxidation of deactivated 1,1-disubstituted alkenes to terminal epoxides containing a quaternary stereogenic center.

An asymmetric Diels-Alder cycloaddition of δ,δ-disubstituted 2,4-dienones by trienamine catalysis with cinchona-based primary amines has been developed. In their Communication (DOI: 10.1002/anie.201200248), Y.-C. Chen and co-workers show that a wide range of electron-deficient dienophiles were tolerated in this reaction to afford multifunctional cyclohexene derivatives with excellent stereoselectivity.

The welwitindolinones with bicyclo[4.3.1] cores are a class of natural products that have attracted tremendous interest from the synthetic community because of their fascinating structures and promising biological profiles. More than 15 research groups worldwide have reported progress toward these elusive natural products. This Minireview describes contemporary studies aimed at ...

About 30 % of the world's iodine production comes from the Chiba area in Japan, shown in the background of the picture (Map data ©2012 ZENRIN Imagery ©2012 TerraMetrics). Enantiomerically pure hypervalent iodine compounds are the key for metal-free, highly stereoselective oxyaminations of alkenes. This reaction can be used for the ...

The stereocontrolled synthesis of the β-branched anti,anti-dipropionate stereotriad 4 via aldol or crotylmetal chemistry represents a historical challenge to the organic synthesis community. Here we describe a general solution to the long-standing problem associated with the synthesis of 4 by utilizing mismatched double asymmetric crotylboration reactions of enantioenriched α-methyl substituted ...

An organoimido-substituted monovacant hexamolybdate containing additional multidentate ligands and its phenylphosphonate derivative were both synthesized directly from an aromatic amine by using an N,N-dicyclohexylcarbodiimide (DCC) protocol. The inherent chirality of these compounds and their hydrophobic shells are pictured.

In this communication we describe an unprecedented catalytic asymmetric heterodimerization of ketenes of wide substrate scope. The alkaloid-catalyzed method provides access to ketene heterodimer beta-lactones and allows even two different monosubstituted ketenes to be cross-dimerized, with excellent enantioselectivity (17 examples with ≥90% ee) and excellent heterodimer regioselectivity observed in all ...

A new flavane glucoside, 7,2'-dihydroxy-8-hydroxyethyl-4'-methoxyflavane-2'-O-β-d-glucopyranoside (3), along with three known flavonoids, 7,2'-dihydroxy-8-prenyl-4'-methoxyflavane (1), euchrenone a(7) (2), and 7,2'-dihydroxy-8-prenyl-4'-methoxy-2'-O-β-d-glucopyranosylflavane (4), was isolated from silkworm droppings. The structures of the compounds were elucidated on the basis of 1D and 2D NMR spectroscopic analyses and optical rotational characteristics. The compounds isolated from silkworm ...

From an in-house library of compounds, five phenothiazines and one dibenzothiadiazepine were selected to be tested in neuroprotective and cholinergic assays. Three of them, derived from the N-alkylphenothiazine, the N-acylaminophenothiazine, and the 1,4,5-dibenzo[b,f]thiadiazepine system, protected human neuroblastoma cells against oxidative stress generated by both exogenous and mitochondrial free radicals. They ...

Several routes for the synthesis of m-terphenyl thio-, seleno-, and telluroethers were investigated. m-Terphenyl iodides react with diphenyl diselenides or ditellurides (CsOH·H(2)O, DMSO, 110 °C) to give the desired compounds in 19-84% yield which significantly extends the previously reported such reactions because o-benzyne cannot be an intermediate as previously suggested. ...

BACKGROUND: Elimination of free radicals to prevent oxidation has played a major role in the development and product differentiation of the latest generation of highly cross-linked ultra-high molecular weight polyethylene bearing materials. In the current study, we (1) examined oxidation in a series of retrieved remelted highly cross-linked ultra-high molecular ...

Polyacrylamide grafted starch (St-g-PAM) was made by a novel method of synthesis, involving combination of microwave radiation and a chemical free radical initiator (ceric ammonium nitrate) to initiate grafting reaction. This method (microwave assisted synthesis) is quick, highly reliable, reproducible and yields high quality product as compared to the conventional ...

Free radicals are by-products of metabolism and exist in a homeostasis between generation and scavenging in vivo. Excessive free radicals cause various diseases, including nervous system diseases. Neuroglobin (Ngb), a nervous system-specific oxygen-binding protein, has been suggested to be a potential free radical scavenger in the nervous system in vivo; ...

Polyhydroxylated fullerenes (fullerenols: C(60)(OH)(n)) are known as the major water-soluble fullerene derivatives which possess particular significance as free radical scavengers or antioxidants in biological systems. Recently, the novel polyhydroxylated fullerene (C(60) (OH)(44)·8H(2)O: SHH-F) was successfully synthesized. In the present study, we investigated the radical-scavenging effects and cytoprotective effects of three ...

Symmetrical 1,3-diyne compounds can be easily synthesized via a transition-metal-free homocoupling reaction of 1-haloalkynes without base and oxidant. The method shows excellent functional group compatibility and high yields.

A new general reaction for the preparation of isomerically pure hydroxyalkylated C(60) monoadducts, via the free radical photochemical addition of alcohols to [60]fullerene, is described.

Free radicals generation is inhibited through green light (GL) irradiation in cellular systems and in chemical reactions. Standard melanocyte cultures were UV-irradiated and the induced cellular reactive oxygen species (ROS) were quantified by the fluorescence technique. The same cell cultures, previously protected by a 24h GL exposure, displayed a significantly ...

A general and robust racemization-free protocol for the synthesis of a variety of N-tert-butanesulfinyl ketimines is reported. Reaction progress was monitored by (1)H NMR using the nonperturbing internal standard diglyme, and ketimines were formed in good to high yields in either THF or CPME (cyclopentyl methyl ether) as solvent with ...

The free-radical-mediated bromoallylation of acetylenes proceeded efficiently in the presence of V-65 (2,2-azobis(2,4-dimethylvaleronitrile)) as the radical initiator. The regioselective reaction, which yields 1-bromo-2-substituted 1,4-dienes, is complementary to the Pd-catalyzed bromoallylation reaction previously reported by Kaneda. The products of the free-radical-mediated bromoallylation of acetylenes could be converted into a variety of ...

A diamine-free protocol for the s-BuLi-mediated lithiation-trapping of N-Boc heterocycles has been developed. In the optimized procedure, lithiation is accomplished using s-BuLi in THF at -30 °C for only 5 or 10 min. Subsequent electrophilic trapping or transmetalation-Negishi coupling delivered a range of functionalized pyrrolidines, imidazolidines, and piperazines in 43-83% ...

Quercetin, one of the most common dietary flavonols, was investigated in the presence of Cu(II) ions in methanolic solution in order to obtain some explanation on the mechanism interaction and its action against free radical-mediated damage. The spectroscopic studies (UV-VIS, IR, ESI-MS) were used to assess the extent to which ...

Conducting polymer-coated polystyrene latex particles were synthesized in one pot using ammonium persulfate as an initiator for free radical polymerization of styrene and a chemical oxidant for chemical oxidative polymerization. Pressed pellets of the core-shell particles showed an efficient electrical conduction.

A free radical multicomponent reaction mediated by an acidic TiCl(4)-Zn/H(2)O(2) system allows the assembly of an amine, a ketone, and formamide in one pot, affording instant access to quaternary alpha-amino acid derivatives.

Highly reactive cyclooctynes have been sought as substrates for Cu-free cycloaddition reactions with azides in biological systems. To elevate the reactivities of cyclooctynes, two strategies, LUMO lowering through propargylic fluorination and strain enhancement through fused aryl rings, have been explored. Here we report the facile synthesis of a difluorobenzocyclooctyne (DIFBO) ...

A metal-free catalytic system with N,N',N″-trihydroxyisocyanuric acid (THICA) as the catalyst for the oxidation of nitrotoluenes is introduced, and a novel Pd-free approach for the synthesis of THICA was developed. In a solution of acetic acid, THICA and concentrated nitric acid, nitrotoluenes especially polynitrotoluenes such as 2,4,6-trinitrotoluene (TNT), were converted ...

In the last few decades, virtual screening has proved to be able to guide the selection of new hit compounds with predefined biological activity. However, the usage of these computational techniques is often associated with resource- and time-consuming preparation protocols. In this work we present Commercial Compound Collection (CoCoCo), a ...

An ultrasound-assisted preparation of 1,4-diazabutadienes via smooth condensation of diketones with amines under solvent-free conditions is described. The generality of this method was examined by the synthesized N,N'-diaryl- and N,N'-dialkyl-1,4-diazabutadiene derivatives. In addition to experimental simplicity, the main advantages of the procedure are mild conditions, short reaction time (2-15 min) ...

The free-radical-scavenging activities of various solvent extracts of Microcos paniculata were evaluated through in vitro model systems, such as 1,1-diphenyl-2-picrylhydrazyl (DPPH), 2,2'-azino-bis-(3-ethylbenzothiazoline-6-sulfonate) (ABTS) and Co (II) EDTA-induced luminol chemiluminescence by flow injection. In all three of these systems the ethyl acetate (EtOAc) extract showed the highest free-radical-scavenging activity compared with ...

An application has been developed to help with the creation and editing of Systems Biology Markup Language (SBML) format metabolic networks up to the organism scale. Networks are defined as a collection of Kyoto Encyclopedia of Genes and Genomes (KEGG) LIGAND reactions with an optional associated Enzyme Classification (EC) number ...

Deuterium exchange of a carboxy group was achieved by photochemical decarboxylation of free carboxylic acids in the presence of thiol and a small amount of D(2)O, and a deuterated product with excellent deuterium content was obtained; this reaction is a practical means of synthesizing regioselective deuterium-labelled compounds under mild reaction ...

Free radicals are known to cause cellular damage and are present in ophthalmic preparations. Corneal defence mechanisms are bypassed in intra-ocular surgery. We evaluated commonly used intracameral agents to ascertain the presence of free radicals and investigate the possibility of anterior segment and endothelial toxicity. Samples of 19 commonly used ...

The organotin monomer di(tri-n-butyltin) citraconate (DTBTC, I) was synthesized. Subsequently this monomer was copolymerized with N-vinylimidazole (VI) using a free radical technique. The overall conversion was kept low (< or = 14% wt/wt) for all studied samples and the copolymer composition was determined from tin analysis using the Gilman and ...

Exposure of Caco-2 cells to indometacin can be a useful model to assess some of the cytotoxic events that appear to underlie the gastrointestinal lesions associated with the use of this anti-inflammatory agent. Using such a cellular model, we addressed here the cytoprotective potential of a recently standardized apple peel ...

Thiol-ene click chemistry was used for the attachment of a variety of functional molecules onto oxide-free Si(111) surfaces using very mild conditions; the efficient nature of this coupling strategy allowed for successful light-induced micropatterning and thus provides a novel route towards biofunctional electronics.

Cyanidin-3-rhamnoglucoside (C3R) is the major anthocyanin in fresh fig fruits. In this study, the free radical scavenging potential of C3R was evaluated in vitro using several free radical generators. This naturally occurring anthocyanin was superior to other tested natural antioxidants in scavenging ABTS(*+). Electron paramagnetic resonance served to determine the ...

A linker-free connected reduced graphene oxide/CdSe nanoparticle (R-GO/CdSe NP) nanocomposite was produced by directly anchoring CdSe NPs onto R-GO. The morphological and structural characterizations evidence that the single-crystal CdSe NPs with the size of a few tens of nanometers can be efficiently decorated on the R-GO. The photoresponse of this ...

Polyunsaturated fatty acids (PUFA) are important constituents in all eukaryotic organisms, contributing to the structural integrity of biological membranes and serving as precursors for enzymatically-generated local hormones. In addition to these functions, PUFA can generate by a free radical-initiated mechanism, key products which participate in a variety of pathophysiological processes. ...

The ethanol extracts of 30 mushroom species from the order Polyporales were tested for their free radical scavenging activities by means of the DPPH free-radical scavenging and hydrogen peroxide-induced luminol chemiluminescence assays. In the DPPH radical scavenging test, 7 species gave EC50 values of less than 1 mg/mL. The highest ...

The phenanthroindolizidine alkaloid (S)-(+)-tylophorine was synthesized from L-proline in nine linear steps including a double bromination and a free-radical cyclization of an N-aziridinylimine as the key steps. The phenanthrene moiety was prepared from homoveratric acid and veratraldehyde and permits the variation of each oxygen-substituted ring.

An efficient one-pot method to generate structurally diverse and medicinally interesting pyrazolone derivatives in good to excellent yields of 51-98% under microwave irradiation and solvent-free conditions has been developed.

Free radicals are molecules with one or more unpaired electron(s) commonly found in seminal plasma. Physiologically, free radicals control sperm maturation, capacitation and hyperactivation, the acrosome reaction, and sperm-oocyte fusion. Pathologically, free radicals induce lipid peroxidation, DNA damage and apoptosis of spermatozoa. The present review deals with both the beneficial ...

The photodecomposition of ketones by the Norrish Type I reaction, leading to the efficient release of reducing ketyl or alpha-amino alkyl radicals, provides a facile route for the synthesis of copper nanoparticles (CuNP) in both aqueous and organic solvents. The role of different counterions (especially halides) and surfactants has been ...

Oxidative stress is implicated as one of the key causes underlying many diseases. Free radicals are important constituents of basal physiology. Assessment of free radicals or the end products of their action has proved to be difficult. Consequently, authentication of the contribution of free radicals to physiology and pathology has ...

Bioorthogonal chemical reactions are paving the way for new innovations in biology. These reactions possess extreme selectivity and biocompatibility, such that their participating reagents can form covalent bonds within richly functionalized biological systems--in some cases, living organisms. This tutorial review will summarize the history of this emerging field, as well ...

Hydrogen is a major component of interstellar space and the fuel that sustains the stars. However, it is seldom regarded as a therapeutic gas. A recent study provided evidence that hydrogen inhalation exerted antioxidant and anti-apoptotic effects and protected the brain against ischemia-reperfusion injury by selectively reducing hydroxyl radical and ...

A N-heterocyclic carbene, namely, 1,3-bis-(diisopropyl)imidazol-2-ylidene either directly initiates or catalyzes the metal-free ring opening polymerization of neat propylene oxide at 50 degrees C, affording well-defined alpha,omega-heterodifunctionalized poly(propylene oxide) oligomers.

Melatonin, an endogenous hormone, is used as an antioxidant drug in doses quite higher than the endogenous circulating levels of this hormone. Hepatic endoplasmic reticulum contains the cytochrome P450 (CYP450) system, which catalyzes one biotransformation pathway of melatonin; this organelle is also one of the main sources of reactive oxygen ...