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Triazoles
Terms modified by Triazoles Selected AbstractsSynthesis and Characterization of the Nitrogen-Rich Hyperbranched Polymers , Poly([1,2,3]-Triazole-[1,3,5]-Triazine)sPROPELLANTS, EXPLOSIVES, PYROTECHNICS, Issue 6 2008Georgiy Abstract Novel hyperbranched poly([1,2,3]-triazole-[1,3,5]-triazine)s (HBP TT) were synthesized by a 1,3-dipolar cycloaddition reaction from AB2 monomer , 2-azido-4,6-bis-prop-2-yn-1-yloxy- [1,3,5]-triazine (ABPOT). The monomer contains one azide group A and two terminal alkyne units B. Thermal polymerization of ABPOT in bulk or in DMF solution leads to hyperbranched polymers containing both 1,4- and 1,5-disubstituted [1,2,3]-triazoles. The monomer was also polymerized catalytically in the presence of Cu(I) salts under mild reaction conditions in DMSO solution and in bulk affording hyperbranched poly-[1,2,3]-triazoles 1,4-disubstituted only. The reactions lead to the products soluble in aprotic polar solvents like DMSO or DMF. Side reactions can proceed in a few cases, particularly: (i) homocoupling of alkyne groups, leading to the formation of insoluble products as a result of cross-linking, (ii) isomerization of propynyloxytriazine fragments to propynyl- or propadienyltriazinone ones, and (iii) hydrolysis of triple bonds without the loss of solubility. Heats of formation of monomer and synthesized polymers were calculated from their combustion heats. All products were characterized by NMR-, IR-spectroscopy, and size exclusion chromatography (SEC) data. The obtained results open the prospect for the use of HBP TT as the high-enthalpy modifiers for energetic and non-energetic binders. [source] Kupferkatalysierte Azid-Alkin-Cycloadditionen: regioselektive Synthese von 1,4,5-trisubstituierten 1,2,3-Triazolen,ANGEWANDTE CHEMIE, Issue 1 2010Christian Spiteri Aller guten Dinge sind drei: Nur wenige Methoden wurden beschrieben, die einen effizienten, hoch regioselektiven Zugang zu trisubstituierten Triazolen eröffnen. Dies regte die Suche nach neuen Reaktivitäten und die Entwicklung neuer Methoden an. Ein neues, effizientes, robustes Eintopfverfahren zur Synthese hoch funktionalisierter, trisubstituierter Triazole (oben im Schema) ist eine wichtige Erweiterung für das Repertoire der Klickreaktionen. [source] ChemInform Abstract: Efficient Synthesis of (E)-,-Haloenones Through Chemoselective Alkyne Activation over Allene with Triazole,Au Catalysts.CHEMINFORM, Issue 39 2010Dawei Wang Abstract The reaction proceeds with internal aromatic and aliphatic alkynes, whereas terminal ones fail. [source] ChemInform Abstract: Synthesis of New 4-Pyrrol-1-yl Benzoic Acid Hydrazide Analogues and Some Derived Oxadiazole, Triazole and Pyrrole Ring Systems: A Novel Class of Potential Antibacterial and Antitubercular Agents.CHEMINFORM, Issue 10 2009S. D. Joshi Abstract ChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 200 leading journals. To access a ChemInform Abstract of an article which was published elsewhere, please select a "Full Text" option. The original article is trackable via the "References" option. [source] Use of Polyfunctionalized Ethylene Synthons: Convenient Synthesis of Biologically Active Trifluoromethyl Containing N-Substituted-benzoylpyrazoles and Triazole.CHEMINFORM, Issue 23 2006Ming Li Abstract ChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 200 leading journals. To access a ChemInform Abstract, please click on HTML or PDF. [source] Triazole-Based Monophosphines for Suzuki,Miyaura Coupling and Amination Reactions of Aryl Chlorides.CHEMINFORM, Issue 10 2006Duan Liu Abstract ChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 200 leading journals. To access a ChemInform Abstract, please click on HTML or PDF. [source] Efficient Synthesis of 5-Fluoroalkylated 1H-1,2,3-Triazoles and Application of the Bromodifluoromethylated Triazole to Prepare New gem-Difluorinated Triazole Compounds.CHEMINFORM, Issue 19 2003Weimin Peng Abstract For Abstract see ChemInform Abstract in Full Text. [source] Alkylations of N4 -(4-Pyridyl)-3,5-di(2-pyridyl)-1,2,4-triazole: First Observation of Room-Temperature Rearrangement of an N4 -Substituted Triazole to the N1 AnalogueCHEMISTRY - AN ASIAN JOURNAL, Issue 4 2010Jonathan Abstract Attempts to use alkylation to introduce a positive charge at the nitrogen atom of the 4-pyridyl ring in the bis(bidentate) triazole ligand N4 -(4-pyridyl)-3,5-di(2-pyridyl)-1,2,4-triazole (pydpt) were made to ascertain what effect a strongly electron-withdrawing group would have on the magnetic properties of any subsequent iron(II) complexes. Alkylation of pydpt under relatively mild conditions led in some cases to unexpected rearrangement products. Specifically, when benzyl bromide is used as the alkylating agent, and the reaction is carried out in refluxing acetonitrile, the N4 substituent moves to the N1,position. However, when the same reaction is performed in dichloromethane at room temperature, the rearrangement does not occur and the desired product containing an alkylated N4 substituent is obtained. Heating a pure sample of N4 -Bzpydpt,Br to reflux in MeCN resulted in clean conversion to N1 -Bzpydpt,Br. This is consistent with N4 -Bzpydpt,Br being the kinetic product whereas N1 -Bzpydpt,Br is the thermodynamic product. When methyl iodide is used as the alkylating agent, the N4 to N1 rearrangement occurs even at room temperature, and at reflux pydpt is doubly alkylated. The observation of the lowest reported temperatures for an N4 to N1 rearrangement is due to this particular rearrangement involving nucleophilic aromatic substitution: a possible mechanism for this transformation is suggested. [source] Epoxiconazole causes changes in testicular histology and sperm production in the Japanese quail (Coturnix coturnix japonica)ENVIRONMENTAL TOXICOLOGY & CHEMISTRY, Issue 11 2008Konstanze Grote Abstract The fungicide epoxiconazole (Epox), a triazole, belongs to the group of azole compounds that are extensively used as fungicides in various fruit crops. The frequent use of agricultural lands for wintering by migrating birds can be the source of their increased dietary intake of agricultural pesticides. We investigated whether exposure to Epox causes effects on avian fertility and reproduction, using the Japanese quail (Coturnix coturnix japonica) as a model species for the assessment of reproductive effects of pesticides in wild birds. Epox was administered to adult Japanese quail for three weeks at dietary levels of 10, 50, and 500 ppm, and possible effects on reproduction were investigated. Epox administration resulted in a significantly decreased number of spermatids in the 50- and 500-ppm dose groups. Histopathology showed a reduced number of testicular canaliculi with visible germ cells and a reduction in spermatid number. However, testis weight was not affected up to the highest dose level. No impact was observed on hormone levels, fertility, and reproductive outcome, as laying rate and percentage of fertile eggs were not altered. Likewise, treatment had no influence on the egg or chick parameters evaluated. A time- and dose-related transfer of Epox into the eggs was determined in all treatment groups. We conclude that dietary treatment of Japanese quail with 50 and 500 ppm of the triazole fungicide Epox resulted in a clear impact on the testis. The evaluation of the additional endpoints spermatid count and testicular histology have proven useful and are recommended for future studies on avian reproduction. [source] Betaine Adducts of N-Heterocyclic Carbenes: Synthesis, Properties, and ReactivityEUROPEAN JOURNAL OF INORGANIC CHEMISTRY, Issue 13 2009Lionel Delaude Abstract N-Heterocyclic carbenes (NHCs) form stable zwitterionicadducts with a range of heteroallenes, ketenes, and allenes. Although the first representatives of this class of inner salts were first investigated as far back as the 1960s, they have enjoyed a sustained interest from the chemical community over the years. Depending on the nature of their anionic moiety, NHC betaines display a very broad palette of reactivities and have found applications in various fields of organic synthesis and catalysis. In this Microreview, the synthesis, properties, and reactivity of NHC betaines are surveyed. The NHCs under consideration include ylidenes derived from imidazole, benzimidazole, imidazoline, thiazole, or triazole, and the heteroallenes investigated so far are carbon dioxide, carbon disulfide, isocyanates, isothiocyanates, and their selenium analogues. A historical background is provided for each type of adduct under consideration, but emphasis is placed mainly on developments that have appeared in the literature within the past few years. (© Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2009) [source] Fluoride-Free Hiyama and Copper- and Amine-Free Sonogashira Coupling in Air in a Mixed Aqueous Medium by a Series of PEPPSI-Themed Precatalysts,EUROPEAN JOURNAL OF INORGANIC CHEMISTRY, Issue 12 2009Chandrakanta Dash Abstract A new series of robust, user-friendly, and highly active PEPPSI-themed (pyridine-enhanced precatalyst preparation, stabilization and initiation) (NHC)PdX2(pyridine)-type (X = Cl, Br) precatalysts of C4,C5 saturated imidazole- (1,4) and triazole-based (5 and 6) N-heterocyclic carbenes for the Hiyama and Sonogashira couplings under amenable conditions are reported. Specifically 1,6 efficiently catalyze the fluoride-free Hiyama coupling of aryl halides with PhSi(OMe)3 and CH2=CHSi(OMe)3 in air in the presence of NaOH as a base in a mixed aqueous medium (dioxane/H2O, 2:1 v/v). Along the same lines, these 1,6 precatalysts also promote the Cu-free and amine-free Sonogashira coupling of aryl bromides and iodides with phenylacetylene in air and in a mixed aqueous medium (DMF/H2O, 3/1 v/v). The complexes 1,6 were synthesized by the direct reaction of the respective imidazolinium and triazolium halide salts with PdCl2 in pyridine in the presence of K2CO3 as a base. DFT studies on the catalytically relevant palladium(0) (NHC)Pd(pyridine) precursors 1a,6a reveal significant donation from the N-heterocyclic carbene lone pair onto the unfilled ,* orbital of the trans Pd,pyridine bond. This weakens the Pd-bound "throwaway" pyridine ligand, and its dissociation marks the initiation of the catalytic cycle.(© Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2009) [source] Click Chelators for Platinum-Based Anticancer DrugsEUROPEAN JOURNAL OF INORGANIC CHEMISTRY, Issue 2 2008Aurélie Maisonial Abstract Triazoles from "click chemistry" are convenient ligands for the formation of platinum complexes bearing combined triazole,amine or triazole,carboxylate moieties. Striking differences in the chelation modes are observed between the two series. One of the triazole,amine platinum complexes exhibits selective cytotoxicity against breast cancer cells lines. (© Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2008) [source] Bright and Efficient, Non-Doped, Phosphorescent Organic Red-Light-Emitting Diodes,ADVANCED FUNCTIONAL MATERIALS, Issue 12 2004Y.-H. Song Abstract Ir(III) metal complexes with formula [(nazo)2Ir(Fppz)] (1), [(nazo)2Ir(Bppz)] (2), and [(nazo)2Ir(Fptz)] (3) [(nazo)H,= 4-phenyl quinazoline, (Fppz)H,=,3-trifluoromethyl-5-(2-pyridyl) pyrazole, (Bppz)H,=,3- t -butyl-5-(2-pyridyl) pyrazole, and (Fptz)H,=,3-trifluoromethyl-5-(2-pyridyl) triazole] were synthesized, among which the exact configuration of 1 was confirmed using single-crystal X-ray diffraction analysis. These complexes exhibited bright red phosphorescence with relatively short lifetimes of 0.4,1.05,,s in both solution and the solid-state at room temperature. Non-doped organic light-emitting diodes (OLEDs) were fabricated using complexes 1 and 2 in the absence of a host matrix. Saturated red electroluminescence was observed at ,max,=,626,nm (host-emitter complex,1) and 652,nm (host-emitter complex,2), which corresponds to coordinates (0.66,0.34) and (0.69,0.31), respectively, on the 1931 Commission Internationale de l'Eclairage (CIE) chromaticity diagram. The non-doped devices employing complex,1 showed electroluminance as high as 5780,cd,m,2, an external quantum efficiency of 5.5,% at 8,V, and a current density of 20,mA,cm,2. The short phosphorescence lifetime of 1 in the solid state, coupled with its modest ,,, stacking interactions, appear to be the determining factors for its unusual success as a non-doped host-emitter. [source] Heterocyclic synthesis containing bridgehead nitrogen atom: Synthesis of 3-[(2H)-2-oxobenzo[b]pyran-3-yl]- s -triazolo[3,4- b]-1,3,4-thiadiazine and thiazole derivativesHETEROATOM CHEMISTRY, Issue 2 2003M. A. Raslan The reaction of 2H-2-oxobenzo[b]pyran-3-hydrazide (2) with carbon disulfide in basic DMF afforded potassium thiocarbamate 3, which readily underwent heterocyclization upon its reaction with hydrazine and/or phenacyl bromide to yield 1,2,4-tiazole (4) and thiazole 7 derivatives, respectively. Condensation of 4 with substituted phenacyl bromide and/or chloranil gave 1,2,4-triazole[3,4-b]thiadiazine (5a,b) and 3,10-bis-[2H-2-oxobenzo[b]pyran-3-yl]-6,13-dichloro-bis-1,2,4-triazolo[3,4-b]-1,3,4-thiadiazino[5,,6,-b:5,,6,-e]cyclohexa-1,4-diene (6), respectively. Cyclization of thiosemicarbazide 10 by refluxing it in sodium hydroxide and/or phosphoryl chloride afforded triazole 13 and thiadiazole 15 derivatives, respectively. Also, 10 reacted with phenacyl bromide in the presence of anhydrous sodium acetate to give the oxothiazolidine derivative 17. The structure of the synthesized compounds were confirmed by elemental analyses, IR, 1H NMR, and mass spectra. © 2003 Wiley Periodicals, Inc. Heteroatom Chem 14:114,120, 2003; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/hc.10109 [source] Copper Nanoparticles on Charcoal for Multicomponent Catalytic Synthesis of 1,2,3-Triazole Derivatives from Benzyl Halides or Alkyl Halides, Terminal Alkynes and Sodium Azide in Water as a "Green" SolventADVANCED SYNTHESIS & CATALYSIS (PREVIOUSLY: JOURNAL FUER PRAKTISCHE CHEMIE), Issue 1-2 2009Hashem Sharghi Abstract A one-pot procedure for synthesis of 1,2,3-triazole derivatives via the three-component coupling (TCC) reaction between terminal alkynes, benzyl or alkyl halides, and sodium azide in the presences of 1,mol% nanoparticles copper/carbon (Cu/C) catalyst has been developed. The catalyst showed high catalytic activity and 1,4-regioselectivity for the [3+2],Huisgen cycloaddition in water as a "green" solvent and good to excellent yields were obtained in all cases. This procedure eliminates the need to handle organic azides, and they are generated in situ. The reaction has a broad scope and is especially practical for the synthesis of new azacrown ether and anthraquinone derivatives of triazole. The heterogeneous catalysts were fully characterized by scanning electron microscopy (SEM), atomic forced microscopy (AFM), X-ray diffraction (XRD), inductively coupled plasma (ICP) analysis and FT-IR experimental techniques. The catalyst was recycled ten times without significant loss of activity. [source] Alkylation of azoles: Synthesis of new heterocyclic-based AT1 -non-peptide angiotensin (II) receptor antagonistsJOURNAL OF HETEROCYCLIC CHEMISTRY, Issue 3 2007Amal Al-Azmi Several novel analogues of Losartan 2 were synthesized as potential non-peptide angiotensin (II) receptor antagonists. In these non-peptide analogues, the tetrazole and the substituted imidazole rings of Losartan 2 were replaced, respectively, by a carboxylic acid function or its methyl ester and substituted triazole, imidazole or benzimidazole moieties. The biphenyl bromide precursor 3 (BPE) used to introduce the linker between the acid/ester function and the heterocyclic moiety was synthesized using Suzuki biphenyl coupling and then incorporated into the target molecule by simple nucleophilic substitution. The fixed N-aryl isomeric forms of several azole and benzimidazole tautomers were successfully separated by HPLC using 50% aqueous acetonitrile as eluent. Intermediate reaction products and final target compounds were fully characterized spectroscopically. [source] Studies with enaminones: synthesis of new coumarin-3-yl azoles, coumarin-3-yl azines, coumarin-3-yl azoloazines, coumarin-3-yl pyrone and coumarin-2-yl benzo[b]FuransJOURNAL OF HETEROCYCLIC CHEMISTRY, Issue 4 2001Fathy Mohamed Abel Aziz El-Taweel 3-Acetylcoumarine was condensed with dimethylformamide dimethylacetal (DMFDMA) to yield the enaminone, which reacts readily with hydroxylamine and with hydrazines to yield coumarin-3-ylisoxazoles and coumarin-3-ylpyrazoles respectively. Reaction of the enaminone with benzamidine hydrochloride and 3-amino-1,2,4-1H -triazole affords the pyrimidine and triazolo[3,4- b]pyrimidine. The enaminone reacts with hippuric acid and with the dithiocarboxylic acid to yield pyranones. The reaction of the enaminone with 3-amino-1H -1,2,4-triazole gives the triazolo[3,4- b]pyrimidine. The enaminone underwent self dimerization on reflux in acetic acid ammonium acetate to yield the coumarinyl pyridines and reacted with ketone under the same conditions to yield the pyridine. The reaction of the enaminone with 1,4-benzoquinone and 1,4-naphthoquinone gives benzofuryl coumarine derivatives. [source] The synthesis of novel polycyclic heterocyclic ring systems via photocyclization.JOURNAL OF HETEROCYCLIC CHEMISTRY, Issue 1 2000Photocyclization of 3-chloro- N -(3-phenanthryl)naphtho[1,2- b]thiophene-2-carboxamide (12) furnished only one of the two possible isomers, i.e., naphtho[2,,1,:4,5]thieno[2,3- c]naphtho[1,2- f]quinolin-6(5H)-one (13), which was further elaborated to yield the unsubstituted ring system 7, its triazole 8 and tetrazole 9. The structural confirmation of 7 was accomplished by the total assignment of its 1H and 13C nmr spectra utilizing the concerted two-dimensional nmr spectroscopic experiments. [source] Mechanism of 4-methyl-1,2,4-triazol-3-thione reaction with formaldehydeJOURNAL OF PHYSICAL ORGANIC CHEMISTRY, Issue 5 2008Monika Wujec Abstract We have recently described theoretically the mechanism of the reaction between 4-methyl-1,2,4-triazol-3-thiol and formaldehyde that leads to the N- substituted product, N1 -hydroxymethyl-4-methyl-1,2,4-triazol-3-thione. New experimental findings indicate that the thione tautomeric form in reaction with formaldehyde also yields this product. This observation could not be explained on the basis of previous calculations, which predicted that the thione tautomer undergoes nucleophilic substitution at the sulfur atom, leading to the S- substituted product. We present theoretical explanation of the observed reactivity. We show that under experimental conditions this reaction proceeds with the intervention of the anionic form of the triazole with the Gibbs free energy of activation of only 1.8,kcal/mol. Copyright © 2008 John Wiley & Sons, Ltd. [source] Phenylene vinylene-based electroluminescent polymers with electron transport block in the main chainJOURNAL OF POLYMER SCIENCE (IN TWO SECTIONS), Issue 11 2006Honghao Sun Abstract We report a new route for the design of soluble phenylene vinylene (PV) based electroluminescent polymers bearing electron-deficient oxadizole (OXD) and triazole (TZ) moieties in the main chains with the aryloxy linkage. Both series of the PV-based polymers were prepared by Wittig reaction. By properly adjusting the OXD and/or TZ content through copolymerization, we can achieve an enhanced balance of hole- and electron injections, such that the device efficiency is significantly improved. Light-emitting diodes fabricated from P1, P2, P3, P4, P5, P6, and P7 with the configuration of Indium,Tin Oxide (ITO)/Poly (styrene sulfonic acid) doped poly (ethylenedioxythiophene) (PEDOT)/polymer/Ca/Al, emit bright green light with the maximum peak around 500 nm. For the device using the optimal polymer (P4) as emitting layer, a maximum brightness of 1300 cd/m2 at 20 V and a maximum luminance efficiency of 0.325 cd/A can be obtained. © 2006 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 44: 3469,3478, 2006 [source] Comparative pharmacodynamic interaction analysis of triple combinations of caspofungin and voriconazole or ravuconazole with subinhibitory concentrations of amphotericin B against Aspergillus spp.MYCOSES, Issue 3 2010Joanne P. Demchok Summary Triple combination therapy with an antifungal triazole, echinocandin and amphotericin B (AmB) is used in some centres to treat refractory aspergillosis. The objective of this study was to investigate the effect of subinhibitory concentrations of AmB on the double combinations of caspofungin (CAS) + voriconazole (VOR) or ravuconazole (RAV) against Aspergillus fumigatus, Aspergillus flavus and Aspergillus terreus. Isolates were studied in triplicate against CAS/VOR and CAS/RAV combinations by chequerboard broth microdilution. AmB was added to each double combination at concentrations of 0, 0.1 and 0.2 ,g ml,1. The fractional inhibitory concentration (FIC) index was calculated for the double and triple combinations. Comparative analysis was performed by repeated measures analysis followed by Dunnett's post-test. The double combinations of CAS/RAV and CAS/VOR were synergistic or additive in most conditions. Addition of AmB to the double combinations resulted in increased FIC indices for A. fumigatus and A. flavus. By contrast, AmB increased the synergism of the double combinations decreasing FIC indices for A. terreus (P < 0.05). RAV and VOR displayed similar synergistic activity with CAS. The addition of sub-inhibitory amphotericin B concentrations reduced but did not eliminate the synergistic interaction between the echinocandin and triazole against A. fumigatus and A. flavus, while it increased the synergy against A. terreus. [source] In vitro effects of flutriafol and azoxystrobin on Beauvaria bassiana and its efficacy against Tetranychus urticaePEST MANAGEMENT SCIENCE (FORMERLY: PESTICIDE SCIENCE), Issue 7 2010Mutimura C Gatarayiha Abstract BACKGROUND: Testing the compatibility of chemical pesticides and fungal biocontrol agents is necessary if these two agents are to be applied together in the integrated management of plant pests and diseases. In this study, the fungicides azoxystrobin (a strobilurin) and flutriafol (a triazole) were tested in vitro for their effects on germination of conidia and mycelial growth of Beauveria bassiana (Bals.) Vuill. and in bioassay for their effect on fungal activity against Tetranychus urticae Koch. The fungicides were tested at three different concentrations [recommended rate for field use (1 × X) and the dilutions 10,1× X and 10,2× X]. RESULTS: Flutriafol inhibited growth of mycelia and germination of the fungal conidia at all concentrations tested in vitro, and also reduced the efficacy of B. bassiana in bioassays against mites. The inhibitive effect of azoxystrobin in vitro varied with the concentration applied. A significant effect was observed at 1 × X and 10,1× X concentrations on both the germination of conidia and mycelia growth. At 10,2× X concentration, azoxystrobin showed little effect on B. bassiana. However, when this fungicide was tested in bioassays, none of the concentrations reduced B. bassiana activity against mites. CONCLUSION: Azoxystrobin was most compatible with B. bassiana, while flutriafol was the most harmful. Further studies are required to confirm the negative effect of flutriafol on B. bassiana activity. Copyright © 2010 Society of Chemical Industry [source] Method for estimating decomposition characteristics of energetic chemicalsPROCESS SAFETY PROGRESS, Issue 4 2003Sima Chervin Experimental data on the decomposition characteristics of approximately400 chemicals, representing various classes of energetic materials, were summarized by chemical class and statistically analyzed. Average decomposition characteristics, such as energy of decomposition and decomposition onset temperature, were determined for chemical classes containing the following energetic groups: nitro, nitroso, N-oxide, oxime, hydroxylamine, tetrazole, azide, triazene, triazole, diazo, azo, hydrazine, and perchlorate. Additional statistical information is presented for each chemical class, such as number of chemicals analyzed, ranges, and standard deviations for the decomposition parameters analyzed. For chemical classes containing an energetic group attached to an aromatic ring, the presence and position of another substituting group in the ring can significantly influence the decomposition onset temperature. The study summarizes the list of activating and deactivating functional groups, and the positions in the ring where the strongest activation or deactivation occurs. The authors also recommend a method for estimating decomposition parameters of new chemicals. [source] Synthesis and Characterization of the Nitrogen-Rich Hyperbranched Polymers , Poly([1,2,3]-Triazole-[1,3,5]-Triazine)sPROPELLANTS, EXPLOSIVES, PYROTECHNICS, Issue 6 2008Georgiy Abstract Novel hyperbranched poly([1,2,3]-triazole-[1,3,5]-triazine)s (HBP TT) were synthesized by a 1,3-dipolar cycloaddition reaction from AB2 monomer , 2-azido-4,6-bis-prop-2-yn-1-yloxy- [1,3,5]-triazine (ABPOT). The monomer contains one azide group A and two terminal alkyne units B. Thermal polymerization of ABPOT in bulk or in DMF solution leads to hyperbranched polymers containing both 1,4- and 1,5-disubstituted [1,2,3]-triazoles. The monomer was also polymerized catalytically in the presence of Cu(I) salts under mild reaction conditions in DMSO solution and in bulk affording hyperbranched poly-[1,2,3]-triazoles 1,4-disubstituted only. The reactions lead to the products soluble in aprotic polar solvents like DMSO or DMF. Side reactions can proceed in a few cases, particularly: (i) homocoupling of alkyne groups, leading to the formation of insoluble products as a result of cross-linking, (ii) isomerization of propynyloxytriazine fragments to propynyl- or propadienyltriazinone ones, and (iii) hydrolysis of triple bonds without the loss of solubility. Heats of formation of monomer and synthesized polymers were calculated from their combustion heats. All products were characterized by NMR-, IR-spectroscopy, and size exclusion chromatography (SEC) data. The obtained results open the prospect for the use of HBP TT as the high-enthalpy modifiers for energetic and non-energetic binders. [source] A three-dimensional heterometallic CuI/VIV 1,2-bis(1,2,4-triazol-4-yl)ethane framework: a new insight into the structure of vanadium oxyfluoride coordination hybridsACTA CRYSTALLOGRAPHICA SECTION C, Issue 9 2010Olena V. Sharga The bitopic ligand 1,2-bis(1,2,4-triazol-4-yl)ethane (tr2eth) provides an unprecedented short-distance N1:N2 -triazole bridging of CuI and VIV ions in poly[bis[,4 -1,2-bis(1,2,4-triazol-4-yl)ethane]di-,2 -fluorido-tetrafluoridodi-,2 -oxido-dicopper(I)divanadium(IV)], [Cu2V2F6O2(C6H8N6)2]n. The CuI ions and tr2eth linkers afford a two-dimensional square-grid topology involving centrosymmetric (tr)Cu(,-tr)2Cu(tr) [tr is triazole; Cu,N = 1.9525,(16),2.0768,(18),Å] binuclear net nodes, which are expanded in a third dimension by centrosymmetric [V2O2F6]2, pillars. The concerted ,-tr and ,-O bridging between the CuI and VIV ions allows a multi-centre accommodation of the vanadium oxyfluoride moiety on a cationic Cu/tr2eth matrix [Cu,O = 2.1979,(15),Å and V,N = 2.1929,(17),Å]. The distorted octahedral coordination of [VONF4] is completed by two terminal and two bridging F, ions [V,F = 1.8874,(14),1.8928,(13) and 2.0017,(13),2.1192,(12),Å, respectively]. The resulting three-dimensional framework has a primitive cubic net topology and adopts a threefold interpenetration. [source] Multicenter, noncomparative study of caspofungin in combination with other antifungals as salvage therapy in adults with invasive aspergillosisCANCER, Issue 12 2006Johan Maertens MD Abstract BACKGROUND. Caspofungin inhibits synthesis of ,-1,3-glucan, an essential component of the Aspergillus cell wall. This echinocandin has demonstrated efficacy (45% success) as salvage monotherapy of invasive aspergillosis (IA). Interest remains as to whether caspofungin, in combination with other antifungal classes, can improve the efficacy against IA. METHODS. The study involved 53 adults with documented IA who were refractory to or intolerant of standard antifungal therapy and received caspofungin and 1 other mold-active antifungal agent (at the investigator's discretion). Efficacy was assessed by signs, symptoms, and radiographs at the end of combination therapy and Day 84 after combination therapy initiation. Favorable (complete or partial) responses required significant clinical and radiographic improvement. Diagnoses and outcomes were assessed by an independent expert. RESULTS. Among the 53 patients enrolled the most common underlying diseases were acute leukemia (53%), lymphoma (11%), and chronic leukemia (6%). Pulmonary aspergillosis (81%) was the most common site, and most patients (87%) were refractory to prior therapy. Success at the end of combination therapy and Day 84 was 55% (29/53) and 49% (25/51), respectively. Fifty-seven percent of patients with neutropenia and 54% who received an allogeneic hematopoietic stem cell transplant responded favorably. Survival at Day 84 was 55%. Combination therapy, dosed on average for 31.3 days, was well tolerated. Two (4%) serious drug-related adverse events, both attributed to voriconazole, occurred. None of the patients discontinued caspofungin due to toxicity. CONCLUSIONS. Caspofungin in combination with a triazole or polyene was an effective alternative as salvage therapy for patients with recalcitrant Aspergillus infections. Cancer 2006. © 2006 American Cancer Society. [source] Synthesis and Evaluation of New Thiodigalactoside-Based Chemical Probes to Label Galectin-3CHEMBIOCHEM, Issue 10 2009Monique van Scherpenzeel Abstract Light up galectin: Photoprobes based on thiodigalactoside were prepared for galectin-3, a lectin linked to cancer. The probes contained either benzophenone or acetophenone moieties as the photolabel for covalent attachment to the protein. One particular probe labeled galectin-3 selectively, even in the presence of cell lysate. New chemical probes were synthesized to label galectin-3. They are based on the high affinity thiodigalactoside ligand. The probes were synthesized with benzophenone or acetophenone moieties as the photolabel for covalent attachment to the protein. Besides labeling the protein, these aromatic photolabels also greatly enhance the affinity of the probes towards galectin-3, due to the interaction of the photolabel with two arginine guanidinium groups of the protein. The linkage between the sugar and the photolabel was varied as an ester, an amide, and a triazole. For the amide and triazole derivatives, a versatile synthetic route towards a symmetrical 3-azido-3-deoxy-thiodigalactoside was developed. The new probes were evaluated for their binding affinity of human galectin-3. They were subsequently tested for their labeling efficiency, as well as specificity in the presence of a protein mixture and a human cancer cell lysate. [source] Rapid Diversity-Oriented Synthesis in Microtiter Plates for In Situ Screening of HIV Protease InhibitorsCHEMBIOCHEM, Issue 11 2003Ashraf Brik Dr. Click and go: By using click chemistry based on a new triazole forming reaction condition (see scheme), over 100 triazole compounds generated in microtiter plates from a core structure were screened for HIV protease inhibition in situ without product isolation. Potent inhibitors, active at nanomolar concentrations, against the wild type and drug resistant mutants were identified. [source] Facile Synthesis of Nitrogen Tetradentate Ligands and Their Applications in CuI -Catalyzed N-Arylation and Azide,Alkyne CycloadditionCHEMISTRY - A EUROPEAN JOURNAL, Issue 40 2009Fuwei Li Dr. Abstract Five new tetradentate ligands [NNNN] with benzimidazolyl-imine or amine nitrogen donors have been synthesized in good yields under mild conditions from easily available substrates. trans - N,N,-bis(1-Ethyl-2-benzimidazolylmethylene)cyclohexane-1,2-diimine is the best accelerating ligand in this series that supports the CuI -catalyzed Ullmann N-arylation and the direct three-component azide,alkyne cycloaddition reaction to give the corresponding substituted imidazole, pyrazole, and triazole in high yields. Single-crystal X-ray diffraction analysis of its complex with CuI reveals a novel one-dimensional coordination polymer of the metal chain bridged alternately by the [NNNN] ligand and diiodides. [source] Protease Immobilization on ,-Fe2O3/Fe3O4 Magnetic Nanoparticles for the Synthesis of Oligopeptides in Organic SolventsCHEMISTRY - AN ASIAN JOURNAL, Issue 6 2010Bao-juan Xin Abstract The use of nanobiocatalysts, with the combination of nanotechnology and biotechnology, is considered as an exciting and rapidly emerging area. The use of iron oxide magnetic nanoparticles, as enzyme immobilization carriers, has drawn great attention because of their unique properties, such as controllable particle size, large surface area, modifiable surface, and easy recovery. In this study, various ,-Fe2O3/Fe3O4 magnetic nanoparticles with immobilized proteases were successfully prepared by three different immobilization strategies including A),direct binding, B),with thiophene as a linker, and C),with triazole as a linker. The oligopeptides syntheses catalyzed by these magnetic nanoparticles (MNPs) with immobilized proteases were systematically studied. Our results show that i),for magnetic nanoparticles immobilized ,-chymotrypsin, both immobilization strategies A and B furnished good reusability for the Z-Tyr-Gly-Gly-OEt synthesis, the MNPs enzymes can be readily used at least five times without significant loss of its catalytic performance: ii),In the case of Z-Asp-Phe-OMe synthesis catalyzed by magnetic nanoparticles immobilized thermolysin, immobilization Strategy,B provided the best recyclability: iii),For the immobilized papain, although Strategy,A or B afforded an immobilized enzyme for the first cycle of Z-Ala-Leu-NHNHPh synthesis in good yield, their subsequent catalytic activity decreased rapidly. In general, the ,-Fe2O3 MNPs were better for use as an immobilization matrix, rather than the Fe3O4 MNPs, owing to their smaller particle size and higher surface area. [source] | ||||||||||||||||||||||||||||||||||