- Kinetics of free radicals produced by infrared multiphoton-induced decompositions. 1. Reactions of allyl radicals with nitrogen dioxide and bromine
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A new versatile technique to study quantitatively the gaseous reactions of polyatomic free radicals is described in detail. Free radicals are generated homogeneously in a tubular reactor by the infrared multiphoton-induced decomposition (MPD) of suitable radical precursors. The concentrations of reactants and products (both stable and labile) are monitored by using photoionization mass spectrometry. Reactions of the allyl radical, generated by the MPD of allyl bromide, with nitrogen dioxide and bromine have been studied at 300 K. The measured rate constants are 3.9(±0.8) × 10-11 cm3 s-1 for the C3H5 + NO2 reaction and 9.0(±1.8) × 10-12 cm3 s-1 for the C3H5 + Br2 reaction. The potential of the experimental facility for other kinds of studies is discussed.
- Slagle, Irene R.,Yamada, Fumiaki,Gutman, David
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- Synthesis of C-4-Allyloxy-3 Methoxyphenylcalix[4] resorcinarene from Vanillin and Its application as adsorbent of Pb(II) metal cation
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C-4-allyloxy-3-methoxyphenylcalix[4]resorcinarene had been synthesized from vanillin and its application as adsorbent for Pb(II) metal ion had been carried out. The synthesis was conducted in three steps to obtain the product as pink solid in 78.17% yield. The structure elucidation of the product was performed by IR,1H-NMR and 13C-NMR. Adsorption experiments were carried out in a batch system under variation of medium acidity, interaction time and initial metal concentration. Adsorption kinetics was studied using Lagergren and Ho model, while adsorption isotherm was analyzed by Langmuir and Freundlich equations. The result showed that the Pb(II) adsorption was optimum at pH 4 and at interaction time of 30 minutes. The kinetic study showed that the adsorption of Pb(II) followed pseudo-second order of Ho model with adsorption rate (k) of 1.176 g mg-1 minute-1 . The adsorption followed the Langmuir isotherm model with equilibrium constant (K) was 7.28?10-5 L mol-1 , adsorption capacity (qm) was 1.538 mmol g-1 (318.67 mg/g) and adsorption energy was 33.67 kJ mol-1 .
- Kesuma, Endhy Putra,Ohto, Keisuke,Siswanta, Dwi
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- Kinetics of the Reactions of Unsaturated Hydrocarbon Free Radicals (Vinyl, Propargyl, and Allyl) with Molecular Bromine
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The kinetics of the reactions of three unsaturated free radicals (vinyl, propargyl, and allyl) with molecular bromine have been studied by using a tubular reactor coupled to a photoionization mass spectrometer.The radicals were homogeneously generated by the pulsed photolysis of precursor molecules at 193 nm.The subsequent decays of the radical concentrations were monitored in time-resolved experiments as a function of Br2 concentration to obtain the rate constants of these Br-atom metathesis reactions.Rate constants were measured as a function of temperature to obtain Arrhenius parameters.The following rate constant expressions were obtained (units of the preexponential factor are cm3 molecule-1 s-1 and activation energies are kJ mol-1; the temperature range covered in each study is also indicated): C2H3 + Br2 , C3H3 + Br2 , and C3H5 +/- Br2 .The kinetics of R + Br2 reactions is reviewed, and the factors governing the reactivity of polyatomic free radicals in R + Br2 reactions are discussed.
- Timonen, R. S.,Seetula, J. A.,Gutman, D.
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- Generalized route to metal nanoparticles with liquid behavior
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We report the generalized synthesis of metal nanoparticles with liquid-like behavior. We introduce a thiol-containing ionic liquid, N,N-dioctyl-N-(3-mercaptopropyl)-N-methylammonium bromide, which serves as a ligand for platinum, gold, palladium, and rhodium nanoparticles. A rapid reduction using THF-soluble metal salts in the presence of the thiol generates nanoparticles with tunable sizes and size distributions. The as-synthesized nanoparticles are a solid and decompose before melting. Upon exchange of the halide anion for an amphiphilic sulfonate anion, however, the nanoparticles exhibit liquid-like properties at room temperature. The liquids have high metal loadings; for example, the 2.7 nm platinum nanoparticle liquid is 36% platinum by mass. Copyright
- Warren, Scott C.,Banholzer, Matthew J.,Slaughter, Liane S.,Giannelis, Emmanuel P.,DiSalvo, Francis J.,Wiesner, Ulrich B.
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- O-eugenol: A versatile molecule for production of polyfunctional alkenes via organometallic catalysis
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In this study, the synthesis and cross metathesis of o-eugenol (2-allyl-6-methoxy phenol) has been investigated. Synthesis was conducted through two stages of reaction. The first step in the synthetic procedure was to obtain the intermediate 1-but-3-enyl-2-methoxy benzene. Then the heating of the obtained intermediate will initiate will initiate a [3,3] sigmatropic rearrangement to give the o-eugenol with a good yield. The ruthenium-catalyzed cross-metathesis of o-eugenol derivatives with electron deficient olefins including methyl acrylate, acrylonitrile and acrylamides was also reported. In addition the polymerization of 1-allyl-2-(allyloxy)-3-methoxybenzene was possible by acyclic diene metathesis and this allowed to synthesize a polymer from a natural substrate. All the resulting structures were supported by the spectroscopic data.
- Al-Ayed, Abdullah Sulaiman,Hamdi, Naceur,Peruzzini, Maurizio
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- Synthesis and characterization of ferroelectric liquid crystalline siloxanes containing 4-hydroxyphenyl(2S,3S)-2-chloro-3-methylvalerate
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New series of organosiloxane ferroelectric liquid crystalline materials have been synthesized, and their mesomorphic and physical properties have been characterized. These new series contain bis-siloxane or tris-siloxane unit attached to the flexible alkyl chain end of (2S,3S)-2-chloro-3-methylvalerate. The siloxane molecule induction is helpful to the chiral smectic C (S C) formation and chiral SC* stabilization, and it simultaneously causes the liquid crystal temperature range of chiral S C* to be broader. The siloxane member is helpful in reducing the smectic C (SC) transation shift temperature, and the molecule containing tris-siloxane units shows better effect than the bis-siloxane one. The synthesis and characterization of the new FLCs materials which exhibit SC* phase at room temperature and higher spontaneous polarization are presented.
- Lin, Chih-Hung
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- Nitrogen-fixing of ultrasmall Pd-based bimetallic nanoclusters on carbon supports
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Synthesis of supported Pd-based bimetallic catalysts is of great importance in the heterogeneous catalysis field owing to their optimal geometric and electronic effects. Downsizing active metals to ultrasmall nanocluster (2-reduction at 400–500 °C. Through the nitrogen-fixing strategy, we prepare 9 sub-2 nm Pd-based bimetallic nanocluster catalysts by conventional impregnation process. The prepared supported bimetallic Pd-Pb nanocluster catalyst exhibit a high turnover frequency of 1092 h?1 for the semihydrogenation of phenylacetylene under a mild condition (30 °C, 5 bar H2), along with a high selectivity of >93% to styrene, demonstrating the alloying and small-size effects in the bimetallic nanocluster catalysts.
- Chen, Ping,Liang, Hai-Wei,Shen, Shan-Cheng,Wang, Lei,Xu, Shi-Long,Yin, Peng,Zhang, Le-Le
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- Reaction Acceleration Promoted by Partial Solvation at the Gas/Solution Interface
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The kinetics of organic reactions of different types in microvolumes (droplets, thin films, and sealed tubes) show effects of gas/solution interfacial area, reaction molecularity and solvent polarity. Partial solvation at the gas/solution interface is a major contributor to the 104-fold reaction acceleration seen in bimolecular but not unimolecular reactions in microdroplets. Reaction acceleration can be used to manipulate selectivity by solvent choice.
- Qiu, Lingqi,Wei, Zhenwei,Nie, Honggang,Cooks, R. Graham
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p. 1362 - 1365
(2021/09/14)
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- Enantioselective synthesis of ammonium cations
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Control of molecular chirality is a fundamental challenge in organic synthesis. Whereas methods to construct carbon stereocentres enantioselectively are well established, routes to synthesize enriched heteroatomic stereocentres have garnered less attention1–5. Of those atoms commonly present in organic molecules, nitrogen is the most difficult to control stereochemically. Although a limited number of resolution processes have been demonstrated6–8, no general methodology exists to enantioselectively prepare a nitrogen stereocentre. Here we show that control of the chirality of ammonium cations is easily achieved through a supramolecular recognition process. By combining enantioselective ammonium recognition mediated by 1,1′-bi-2-naphthol scaffolds with conditions that allow the nitrogen stereocentre to racemize, chiral ammonium cations can be produced in excellent yields and selectivities. Mechanistic investigations demonstrate that, through a combination of solution and solid-phase recognition, a thermodynamically driven adductive crystallization process is responsible for the observed selectivity. Distinct from processes based on dynamic and kinetic resolution, which are under kinetic control, this allows for increased selectivity over time by a self-corrective process. The importance of nitrogen stereocentres can be revealed through a stereoselective supramolecular recognition, which is not possible with naturally occurring pseudoenantiomeric Cinchona alkaloids. With practical access to the enantiomeric forms of ammonium cations, this previously ignored stereocentre is now available to be explored.
- Walsh, Mark P.,Phelps, Joseph M.,Lennon, Marc E.,Yufit, Dmitry S.,Kitching, Matthew O.
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- Clean protocol for deoxygenation of epoxides to alkenes: Via catalytic hydrogenation using gold
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The epoxidation of olefin as a strategy to protect carbon-carbon double bonds is a well-known procedure in organic synthesis, however the reverse reaction, deprotection/deoxygenation of epoxides is much less developed, despite its potential utility for the synthesis of substituted olefins. Here, we disclose a clean protocol for the selective deprotection of epoxides, by combining commercially available organophosphorus ligands and gold nanoparticles (Au NP). Besides being successfully applied in the deoxygenation of epoxides, the discovered catalytic system also enables the selective reduction N-oxides and sulfoxides using molecular hydrogen as reductant. The Au NP catalyst combined with triethylphosphite P(OEt)3 is remarkably more reactive than solely Au NPs. The method is not only a complementary Au-catalyzed reductive reaction under mild conditions, but also an effective procedure for selective reductions of a wide range of valuable molecules that would be either synthetically inconvenient or even difficult to access by alternative synthetic protocols or by using classical transition metal catalysts. This journal is
- Fiorio, Jhonatan L.,Rossi, Liane M.
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p. 312 - 318
(2021/01/29)
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- Nickel-Catalyzed Asymmetric Reductive 1,2-Carboamination of Unactivated Alkenes
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Starting from diverse alkene-tethered aryl iodides and O-benzoyl-hydroxylamines, the enantioselective reductive cross-electrophilic 1,2-carboamination of unactivated alkenes was achieved using a chiral pyrox/nickel complex as the catalyst. This mild, modular, and practical protocol provides rapid access to a variety of β-chiral amines with an enantioenriched aryl-substituted quaternary carbon center in good yields and with excellent enantioselectivities. This process reveals a complementary regioselectivity when compared to Pd and Cu catalysis.
- He, Jun,Xue, Yuhang,Han, Bo,Zhang, Chunzhu,Wang, You,Zhu, Shaolin
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supporting information
p. 2328 - 2332
(2020/01/08)
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- Piperazine-promoted gold-catalyzed hydrogenation: The influence of capping ligands
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Gold nanoparticles (NPs) combined with Lewis bases, such as piperazine, were found to perform selective hydrogenation reactions via the heterolytic cleavage of H2. Since gold nanoparticles can be prepared by many different methodologies and using different capping ligands, in this study, we investigated the influence of capping ligands adsorbed on gold surfaces on the formation of the gold-ligand interface. Citrate (Citr), poly(vinyl alcohol) (PVA), polyvinylpyrrolidone (PVP), and oleylamine (Oley)-stabilized Au NPs were not activated by piperazine for the hydrogenation of alkynes, but the catalytic activity was greatly enhanced after removing the capping ligands from the gold surface by calcination at 400 °C and the subsequent adsorption of piperazine. Therefore, the capping ligand can limit the catalytic activity if not carefully removed, demonstrating the need of a cleaner surface for a ligand-metal cooperative effect in the activation of H2 for selective semihydrogenation of various alkynes under mild reaction conditions.
- Barbosa, Eduardo C. M.,Camargo, Pedro H. C.,Fiorio, Jhonatan L.,Hashmi, A. Stephen K.,Kikuchi, Danielle K.,Rossi, Liane M.,Rudolph, Matthias
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p. 1996 - 2003
(2020/04/22)
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- Method for compounding drug intermediate 3-bromopropylene
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The invention provides a method for compounding drug intermediate 3-bromopropylene. The method mainly comprises the following steps that 5 moles of 4-bromotoluene is added into a reaction vessel, thetemperature is heated to 60-65 DEG C, after 6-7 moles of oxalic acid solution is added into, 5.5-6 moles of allylamine is continuously added into, then circulation reflux is carried out for 60-80 minutes, reduced pressure distillation is carried out, cut fraction of 50-55 DEG C is collected, collected distillation is washed by a potassium bicarbonate solution, standing stratification is carried out, an oil layer is taken out, the distillation is washed by a potassium bromide solution, triethylamine solution and ethyl cyanide solution in sequence, then dehydrated by a dehydrating agent to obtain finished 3-bromopropylene.
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Paragraph 0011; 0013; 0014; 0015
(2018/07/30)
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- Accessing Frustrated Lewis Pair Chemistry through Robust Gold@N-Doped Carbon for Selective Hydrogenation of Alkynes
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Pyrolysis of Au(OAc)3 in the presence of 1,10-phenanthroline over TiO2 furnishes a highly active and selective Au nanoparticle (NP) catalyst embedded in a nitrogen-doped carbon support, Au@N-doped carbon/TiO2 catalyst. Parameters such as pyrolysis temperature, type of support, and nitrogen ligands as well as Au/ligand molar ratios were systematically investigated. Highly selective hydrogenation of numerous structurally diverse alkynes proceeded in moderate to excellent yield under mild conditions. The high selectivity toward the industrially important alkene substrates, functional group tolerance, and the high recyclability makes the catalytic system unique. Both high activity and selectivity are correlated with a frustrated Lewis pairs interface formed by the combination of gold and nitrogen atoms of N-doped carbon that, according to density functional theory calculations, can serve as a basic site to promote the heterolytic activation of H2 under very mild conditions. This "fully heterogeneous" and recyclable gold catalyst makes the selective hydrogenation process environmentally and economically attractive.
- Fiorio, Jhonatan Luiz,Gon?alves, Renato Vitalino,Teixeira-Neto, Erico,Ortu?o, Manuel A.,López, Núria,Rossi, Liane Marcia
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p. 3516 - 3524
(2018/04/14)
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- Gold-Ligand-Catalyzed Selective Hydrogenation of Alkynes into cis-Alkenes via H2 Heterolytic Activation by Frustrated Lewis Pairs
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The selective hydrogenation of alkynes to alkenes is an important synthetic process in the chemical industry. It is commonly accomplished using palladium catalysts that contain surface modifiers, such as lead and silver. Here we report that the adsorption of nitrogen-containing bases on gold nanoparticles results in a frustrated Lewis pair interface that activates H2 heterolytically, allowing an unexpectedly high hydrogenation activity. The so-formed tight-ion pair can be selectively transferred to an alkyne, leading to a cis isomer; this behavior is controlled by electrostatic interactions. Activity correlates with H2 dissociation energy, which depends on the basicity of the ligand and its reorganization on activation of hydrogen. High surface occupation and strong Au atom-ligand interactions might affect the accessibility and stability of the active site, making the activity prediction a multiparameter function. The promotional effect found for nitrogen-containing bases with two heteroatoms was mechanistically described as a strategy to boost gold activity. (Graph Presented).
- Fiorio, Jhonatan L.,López, Núria,Rossi, Liane M.
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p. 2973 - 2980
(2017/05/31)
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- One-Step Synthesis of Substituted Benzofurans from ortho- Alkenylphenols via Palladium-Catalyzed C=H Functionalization
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A dehydrogenative oxygenation of C(sp2)=H bonds with intramolecular phenolic hydroxy groups has been developed, which provides a straightforward and concise access to structurally diversely benzofurans from ortho-alkenylphenols. The reaction is catalyzed by palladium on carbon (Pd/C) without any oxidants and sacrificing hydrogen acceptors.
- Yang, Dejun,Zhu, Yifei,Yang, Na,Jiang, Qiangqiang,Liu, Renhua
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supporting information
p. 1731 - 1735
(2016/06/09)
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- Organic base-catalysed solvent-tuned chemoselective carbotrifluoromethylation and oxytrifluoromethylation of unactivated alkenes
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An unprecedented and efficient organic base-catalysed highly chemoselective carbo- and oxytrifluoromethylation of unactivated alkenes with Togni's reagent was developed. The switchable chemoselectivity was tuned by simply changing the organic base catalyst and solvent. Mechanistic studies indicated that a radical cyclization pathway for carbotrifluoromethylation in DMSO and a carbocation pathway for oxytrifluoromethylation in DCE were probably involved.
- Yang, Ning-Yuan,Li, Zhong-Liang,Ye, Liu,Tan, Bin,Liu, Xin-Yuan
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supporting information
p. 9052 - 9055
(2016/07/21)
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- The oxidative dehydrogenation of propane from a process for the preparation of propylene
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The invention discloses a method for preparing propylene by performing oxidative dehydrogenation on propane, and relates to a method for preparing propylene. The method comprises the steps of: heating a catalyst to the temperature of 400 to 700 DEG C, keeping the temperature for 10 to 120 minutes, introducing mixed reaction gas to pass through a catalyst bed layer, and reacting to obtain the product of propylene. The mixed reaction gas propane, oxygen, hydrogen halide gas and inert gas. A small amount of hydrogen halide is introduced into the reaction system to effectively activate the propane, the selectivity of the propylene is more than 80 percent, a once through yield of the propylene is close to 50 percent, and performance of the propylene is much better than the performance of the traditional propylene which is obtained by directly dehydrogenizing and performing oxidative dehydrogenation on the propane; a reaction process is gentle, advanced oxidation for oxidative dehydrogenation of propane to prepare the propylene is greatly suppressed at the presence of halogen hydride, the selectivity of the propylene is greatly improved, and a problem of low selectivity of the propylene at high conversion rate of the propane is solved; and the hydrogen halide is recoverable and reused, energy consumption is low, the employed catalyst is a non-noble metal catalyst, and the components is remained stable during the reaction.
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Paragraph 0031-0034
(2017/04/04)
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- Silica supported palladium phosphine as a robust and recyclable catalyst for semi-hydrogenation of alkynes using syngas
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This work reports a chemo-selective semi-hydrogenation of alkynes to alkenes using silica supported palladium phosphine catalyst with syngas (CO/H2). This developed methodology is an alternative to classical Lindlar catalyst for chemo-selective semi-hydrogenation of alkynes to alkenes. Various alkynes were smoothly convert to alkenes in 60-97% conversion with 85-98% selectivity. The prepared catalyst was well characterized by Field Emmission Gun Scanning Electron Microscopy (FEG-SEM), Energy Dispersive X-ray Spectroscopy (EDS), X-ray Photoelectron Spectroscopy (XPS), Inductively Coupled Plasma- Atomic Emmission Spectroscopy (ICP-AES) analysis techniques. In addition, catalyst was effectively recycled up to four consecutive run without significant loss in its catalytic activity and selectivity.
- Jagtap, Samadhan A.,Sasaki, Takehiko,Bhanage, Bhalchandra M.
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- Dynamic Covalent Chemistry of Nucleophilic Substitution Component Exchange of Quaternary Ammonium Salts
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Dynamic covalent libraries (DCLs) of quaternary ammonium cations were set up by reversible nucleophilic substitution (SN2′ and SN2) exchange reactions of ammonium salts and tertiary amines. The reactions were conducted at 60 °C to generate thermodynamically and kinetically controlled mixtures of quaternary ammonium compounds and tertiary amines, and were accelerated by using iodide as a nucleophilic catalyst. Microwave irradiation was used to assist the exchange reaction between the pyridinium salts and pyridine derivatives. Finally, experiments towards the generation of dynamic ionic liquids were performed. The results of this study pave the way for the extension of dynamic combinatorial chemistry to nucleophilic substitution reactions.
- Kulchat, Sirinan,Lehn, Jean-Marie
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p. 2484 - 2496
(2015/11/02)
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- QUINAZOLINE-2,4-DIONE DERIVATIVES
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The invention relates to antibacterial compounds of formula (I), wherein R1 is H, halogen, (C1-C3)alkyl or (C1-C3)alkoxy; R2 is H, halogen, (C1-C3)alkyl, (C1-C3)alkoxy or pyrrolidin-1-yl; R3 is H, halogen, (C1-C3)alkyl, (C1-C3)alkoxy, vinyl or 2-methoxycarbonyvinyl or R2 and R3 together with the two carbon atoms which bear them form a phenyl ring; R4 is H, halogen, (C1-C3)alkyl or (C1-C3)alkoxy; and R5 is H, (C1-C3)alkyl or cyclopropyl, or R4 and R5 form together a —CH2CH2CH2— group; A is the divalent group —CH2—, —CH2CH2—, #—CH(OH)CH2—*, #—CH2N(R6)—* and —CH2NHCH2—, wherein # indicates the point of attachment to the optionally substituted (quinazoline-2,4-dione-3-yl)methyl residue and * represents the point of attachment to the substituted (oxazolidinon-4-yl)methyl residue; R6 is H or acetyl; Y is CH or N; and Q is O or S; and salts of such compounds.
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(2014/06/25)
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- Iron-catalyzed borylation of alkyl, allyl, and aryl halides: Isolation of an iron(I) boryl complex
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Activation of B2pin2 with tBuLi facilitates the Fe-catalyzed borylation of alkyl, allyl, benzyl, and aryl halides via the formation of Li[B2pin2(tBu)] (1). The reaction of 1 with a representative iron phosphine precatalyst generates the unique iron(I) boryl complex [Fe(Bpin)(dpbz)2] (2).
- Bedford, Robin B.,Brenner, Peter B.,Carter, Emma,Gallagher, Timothy,Murphy, Damien M.,Pye, Dominic R.
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supporting information
p. 5940 - 5943
(2015/01/08)
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- Synthesis of silica bromide as heterogeneous reagent and its application to conversion of alcohols to alkyl bromides
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Silica bromide as heterogeneous reagent is prepared from the reaction of silica gel with PBr3 as a nonhydroscopic, filterable, cheap, and stable yellowish powder that can be stored for months. The results show that the silica bromide is a suitable and efficient reagent for conversion of alcohols to alkyl bromides under mild conditions at room temperature. The easy availability of this reagent makes this simple procedure attractive and a practical alternative to the existing methods.
- Mohanazadeh, Farajollah,Sedrpoushan, Alireza,Zolfigol, Mohammad A.,Veisi, Hojat
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p. 598 - 603,6
(2012/12/11)
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- BIOCOMPATIBLE AND BIODEGRADABLE POLYMERS FROM RENEWABLE NATURAL POLYPHENOLS
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This invention describes the use of resveratrol and curcumin, representatives of naturally occurring polyphenols, in their native form, after hydrogenation, and as their respective allyl derivatives, individually, in combination with themselves and other commercial monomers, to make representative varieties of polymers, e.g., polycarbonates (PC), polyurethanes (PU), co-polymers and biodegradable polymers.
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- 4-Aminophenyldiphenylphosphinite (APDPP), a new heterogeneous and acid scavenger phosphinite - Conversion of alcohols, trimethylsilyl, and tetrahydropyranyl ethers to alkyl halides with halogens or N-halosuccinimides
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A new heterogeneous phosphinite, 4-aminophenyldiphenylphosphinite (APDPP), is prepared and used for the efficient conversion of alcohols, trimethylsilyl ethers, and tetrahydropyranyl ethers to their corresponding bromides, iodides, and chlorides in the presence of molecular halogens or N-halosuccinimides. The amino group in this phosphinite acts as an acid scavenger and removes the produced acid. A simple filtration easily removes the phosphinate by-product.
- Iranpoor, Nasser,Firouzabadi, Habib,Gholinejad, Mohammad
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p. 1006 - 1012
(2007/10/03)
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- Synthesis of hydroxylated hydrocarbons
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Ethylene glycol, other diols, triols, and polyols are made in an efficient manner by reacting dibromides with water in the presence of a metal oxide. An integrated process of dibromide formation, alcohol synthesis, metal oxide regeneration, and bromine recycling is also provided.
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(2008/06/13)
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- Silicaphosphine (Silphos): A filterable reagent for the conversion of alcohols and thiols to alkyl bromides and iodides
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Silicaphosphine (Silphos), [P(Cl)3-n(SiO2) n], as a new heterogeneous reagent is introduced. This reagent converts alcohols and thiols to their corresponding bromides and iodides in the presence of X2 (X=Br, I) in refluxing CH3CN in high to quantitative yields. Use of Silphos provides a highly practical method for the easy separation of the Silphos oxide byproduct by a simple filtration.
- Iranpoor, Nasser,Firouzabadi, Habib,Jamalian, Arezu,Kazemi, Foad
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p. 5699 - 5704
(2007/10/03)
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- Absolute Rate Constants for Reactions of Tributylstannyl Radicals with Bromoalkanes, Episulfides, and α-Halomethyl-Episulfides, -Cyclopropanes, and -Oxiranes: New Rate Expressions for Sulfur and Bromine Atom Abstraction
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Arrhenius rate expressions were determined for the abstraction of bromine atom from 2-phenethyl bromide by tri-n-butylstannyl radical (Bu 3Sn.) in benzene using transient absorption spectroscopy, (log(kabs,Br/M-1 s-1) = (9.21 ± 0.20) - (2.23 ± 0.28)/θ, θ = 2.3RT kcal/mol, errors are 2σ) and for the abstraction of sulfur atom from propylene sulfide to form propylene, (log(ks/M-1 s-1) = (8.75 ± 0.91) - (2.35 ±1.33)/θ). Rate constants for reactions of organic bromides, RBr, with Bu3Sn. were found to vary as R = benzyl (15.6) > thiiranylmethyl (6.2) > oxiranylmethyl (3.1) > cyclopropylmethyl (1.3) > 2-phenethyl (1.0), with kabs,Br = 6.8 × 10 7 M-1 s-1 at 353 K for 2-phenethyl bromide. Bromine abstraction from α-bromomethylthiirane is about 7-fold faster than sulfur atom abstraction and is comparable to the reactivity of a secondary alkyl bromide. The potential surface for the vinylthiomethyl → allylthiyl radical rearrangement at UB3LYP/6-31G(d) and UB3LYP/6-311+G-(2d,2p) levels of theory suggests that the thiiranylmethyl radical is produced about 9 kcal/mol above the allylthiyl radical on the rearrangement surface, consistent with the observed enhancement of the Br atom abstraction from the thiirane and with synchronous C-S bond scission of the thiirane ring. The selectivities reported in this work for S vs Cl and Br abstraction provide applications for radical-based synthesis and new competition basis rate expressions for trialkylstannyl radicals.
- Franz, James A.,Shaw, Wendy J.,Lamb, Claude N.,Autrey, Tom,Kolwaite, Douglas S.,Camaioni, Donald M.,Alnajjar, Mikhail S.
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p. 1020 - 1027
(2007/10/03)
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- Process for functionalising a phenolic compound carrying an electron-donating group
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The invention concerns a method for functionalizing a phenolic compound bearing an electron-donor group, in said group para position, inter alia a method for the amidoalkylation of a phenolic compound bearing an electron-donor group, and more particularly, a phenolic compound bearing an electron-donor group preferably, in the hydroxyl group ortho position. The method for functionalizing in para position with respect to an electron-donor group carried by a phenolic compound is characterised in that the phenolic compound bearing an electron-donor group is subjected to the following steps: a first step which consists of protecting the hydroxyl group in the form of a sulphonic ester function; a second step which consists in reacting the protected phenolic compound with an electrophilic reagent; optionally, a third step deprotecting the hydroxyl group.
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- Phase-Vanishing Methodology for Efficient Bromination, Alkylation, Epoxidation, and Oxidation Reactions of Organic Substrates
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(Matrix presented) In cases where both reactants in a phase-vanishing reaction are less dense than the fluorous phase, an alternative to the U-tube method is to employ a solvent with greater density than the fluorous phase, such as 1,2-dibromoethane. This modification has been successfully applied to the methylation of a phenol derivative with dimethyl sulfate and to the m-CPBA-induced epoxidation of alkenes, N-oxide formation from nitrogen-containing compounds, and S-oxide or sulfone formation from organic sulfides.
- Jana, Nirmal K.,Verkade, John G.
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p. 3787 - 3790
(2007/10/03)
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- Romp with oligomeric uv-absorbers
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The invention relates to metathesis polymers wherein an aromatic group that has UV-light absorbing properties is attached with a bridge group to the polymer. Also disclosed is a polymerisable composition comprising a catalytically effective amount of a penta- or hexavalent ruthenium or osmium carbene catalyst, the process for preparing the metathesis polymer by applying the reaction conditions of Ring Opening Metathesis Polymerisation (=ROMP) to the polymerisable composition; and various technical applications of the metathesis polymers.
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- New phenylalanine derivatives
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Specified phenylalanine derivatives and analogues thereof have an antagonistic activity to α4 integrin. They are used as therapeutic agents for various diseases concerning α4 integrin.
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- Spin chemistry of organometallic compounds. 2. Interaction of N-bromohexamethyldisilazane with allyltriorganolsilanes
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Two instances have been considered demonstrating the influence of organoelement substituent on the reactivity of radicals generated from R3MCH2CH=CH2 (M = Si or Sn) in photoinduced interaction with (Me3Si)2
- Taraban, Marc B.,Kruppa, Alexander I.,Polyakov, Nikolai E.,Voronkov, Mikhail G.,Rakhlin, Vladimir I.,Grigor'ev, Stanislav V.,Volkova, Olga S.,Mirskov, Rudolph G.,Leshina, Tatyana V.
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p. 228 - 234
(2007/10/03)
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- 3-(diarylmethylene)-8-azabicyclo[3.2.1]octane derivatives
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This invention is directed to 3-(diarylmethylene)-8-azabicyclo[3.2.1]octane derivatives useful as δ-opioid or μ-opioid receptor modulators. Depending on their agonist or antagonist effect, the compounds are useful analgesics, immunosuppressants, antiinflammatory agents, agents for the treatment of neurological and psychiatric conditions, medicaments for drug and alcohol abuse, agents for treating gastritis and diarrhea, cardiovascular agents and agents for the treatment of respiratory diseases.
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- Triphenylphosphine/2,3-dichloro-5,6-dicyanobenzoquinone as a new, selective and neutral system for the facile conversion of alcohols, thiols and selenols to alkyl halides in the presence of halide ions
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A mixture of triphenylphosphine (Ph3P) and 2,3-dichloro-5,6-dicyanobenzoquinone in CH2Cl2 affords a complex which in the presence of R4NX (X=Cl, Br, I) converts alcohols, thiols and selenols into their corresponding alkyl halides in high yields at room temperature. The method is highly selective for the conversion of 1° alcohols in the presence of 2° ones and also 1° and 2° alcohols in the presence of 3° alcohols, thiols, epoxides, trimethylsilyl- and tetrahydropyranyl ethers, 1,3 dithianes, disulfides, and amides.
- Iranpoor,Firouzabadi,Aghapour,Vaez zadeh
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p. 8689 - 8693
(2007/10/03)
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- 2,3-oxidosqualene-lanosterol cyclase inhibitors
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The present invention relates to aminocyclohexanol derivatives useful for the treatment and/or prophylaxis of diseases which are associated with 2,3-oxidosqualene-lanosterol cyclase such as hypercholesterolemia, hyperlipemia, arteriosclerosis, vascular diseases, mycoses, gallstones, tumors and/or hyperproliferative disorders, and treatment and/or prophylaxis of impaired glucose tolerance and diabetes.
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- Triazole derivatives
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The present invention relates to triazole and imidazole derivatives of formula I and to their pharmaceutically acceptable acid addition salts. These compounds are NMDA receptor subtype blockers and are useful for the treatment of diseases related to the NMDA receptor.
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- Tricyclic urea compounds
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A compound selected from those of formula (I): in which A, Y, R1, R2 and R3 are as defined in the Specification, and pharmaceutical compositions containing the same, which are useful for treating a mammal afflicted with a disorder of the melatoninergic system.
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- Pyronin antibacterials, process and novel intermediates thereto
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The present invention provides convergent processes for preparing myxopyronins and corallopyronins, compounds useful as antibacterial therapeutics. The present invention also provides novel compositions of matter which are useful for the preparation of pyronin antibiotics.
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- Coupling reactions and coupling-alkylations of thiophenecarbaldehydes promoted by samarium diiodide
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The coupling reactions of 2-thiophenecarbaldehyde with aromatic or aliphatic aldehydes were promoted by samarium diiodide in the presence of hexamethylphosphoramide to give C-5 hydroxyalkylation products. The coupling reactions of 3-thiophenecarbaldehyde occurred at C-2, and the subsequent alkylations occurred at the sulfur atom, accompanied by a concurrent opening of the thiophene ring to afford γ-lactols. Double hydroxyalkylations of 2- and 3-thiophenecarbaldehydes were also carried out under appropriate reaction conditions. Synthetic applications of these thiophenecarbonyl coupling products were demonstrated, for example, by elaboration to furans, butenolides, and thiophene-fused polycyclic compounds.
- Yang, Shyh-Ming,Fang, Jim-Min
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p. 394 - 399
(2007/10/03)
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- BiX3 as an efficient and selective reagent for the halogen exchange reaction
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Bismuth halides are efficient and selective reagents in the halogen exchange reactions carried out under mild conditions. This rapid, high yield reaction proceeds mainly with retention of configuration.
- Boyer, Bernard,Keramane, El Mehdi,Arpin, Severine,Montero, Jean-Louis,Roque, Jean-Pierre
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p. 1971 - 1976
(2007/10/03)
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- Chloropyridylcarbonyl derivatives
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Novel chloropyridylcarbonyl derivatives of the formula STR1 in which Het is STR2 n is 1 or 2, R1 is hydrogen, optionally substituted C1-6 alkyl, optionally substituted C2-6 alkenyl, optionally substituted C3-6 alkynyl, optionally substituted phenyl or optionally substituted pyrimidinyl, and R2 and R3, independently of each other, are hydrogen or C1-4 alkyl, and acid addition salts and metal salt complexes thereof, are outstandingly active as microbicides.
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- Synthesis and use of amino acid fluorides as peptide coupling reagents
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The present invention is directed to the process of preparing a peptide comprising reacting a first amino acid or peptide with an amino acid fluoride of the formula: STR1 or the acid fluoride salts thereof wherein BLK is an N-amino protecting group AA is an amino acid residue and X is H or a protecting group useful, and the first amino and peptide have a free amino group and a blocked carboxy end.
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- Indole derivatives as 5-HT1-like agonists
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Compounds of formula (I) and pharmaceutically acceptable salts thereof, wherein R1 is a substituted alkylene; C3 -C7 cycloalkyl optionally substituted with HO; C3 -C6 alkenyl optionally substituted with aryl; C5 -C7 cycloalkenyl; or C3 -C6 alkynyl; R2 is H; halo; F3 C; NC; R8 R9 NOC; a substituted alkylene; R8 R9 NO2 S; R10 S(O)m ; R12 CON(R11); R10 SO2 N(R11); R8 R9 NOCN(R11); R10 O2 CN(R11); R13 (CH2)n CH=CH; or R7 O are selective 5-HT1 -like receptor agonists useful in the treatment of migraine, cluster headache, chronic paroxysmal hemicrania and headache associated with vascular disorders.
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- Amine compounds, their production and use
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A compound of the formula: STR1 wherein Ar 1 and Ar 2 independently represent an optionally substituted aromatic group; P and Q independently represent a divalent aliphatic hydrocarbon group having at least 2 carbon atoms and optionally having either oxygen or sulfur in the carbon chain; R 1 and R 3 independently represent --CO--R, --CONH--R (R represents a hydrocarbon group or a heterocyclic group) or a hydrocarbon group; R 2 and R 4 independently represent hydrogen or an alkyl group; R 2 and R 4 independently represent hydrogen or an alkyl group; R 1 and R 2 or R 3 and R 4, taken together with the adjacent nitrogen atom, may form a nitrogen-containing heterocyclic group; and j represents 0 or 1, or a salt thereof, has excellent GnRH-receptor antagonizing activity and is useful as a prophylactic and therapeutic agent for hormone-dependent and other diseases.
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- Competitive reactivity as a probe for reaction coordinates in gas-phase ion-molecule chemistry
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Using the method of competitive reactivity of two functional groups in the same molecule, anionic elimination reactions show considerable kinetic selectivity for small differences in leaving group thermochemistry, in structures of the general type YCH2CH2CH2Z, where Y and Z are good anionic leaving groups.
- Holman, Robert W.,Sumpter, Terry L.,Farrar, John,Weigel, Kurt,Bartmess, John E.
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p. 585 - 589
(2007/10/03)
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- The thermal desulfination of allylic sulfonyl halides
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Allylic sulfonyl halides can be generated by halogenolysis of the corresponding triorganotin sulfinates. Allylic sulfonyl bromides and iodides undergo a first order, thermal desulfination with allylic rearrangement to yield the corresponding allylic halides. The desulfination of a cyclic allylic sulfonyl bromide is stereospecific, proceeding with γ-syn bromine migration.
- King, Malcolm D.,Sue, Rodney E.,White, Rodney H.,Young, David J.
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p. 4493 - 4496
(2007/10/03)
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- Kinetics of the nucleophilic substitution of benzyltributylammonium bromide with allyl, butyl, and benzyl chlorides and with benzyl acetate and benzyl ether
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In this study, we investigated the kinetics of the nucleophilic substitutions, RX + (BzBu3NBr) ? RBr + (BzBu3NX), where R = allyl, Bu and Bz, when X = Cl; and X = AcO and BzO when R = Bz. The forward and backward rate constants in addition to the activation energies for R = allyl and Bu were also determined. However, only the rate constants at 35°C were determined for the benzyl compounds with toluene as the solvent to reduce the reaction rate. Moreover, the effects of the structures of the groups R and the leaving groups X on the reactivity were compared. Results in this study can provide valuable information for future studies involving the phase transfer catalyzed displacements.
- Wang, Ten-Tsai,Chang, Chyi-Huang,Huang, Ting-Chia
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p. 615 - 626
(2007/10/03)
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- Solid phase and combinatorial synthesis of benzodiazepine compounds on a solid support
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Methods, compositions, and devices for synthesis of therapeutically useful compounds. The invention provides a rapid approach for combinatorial synthesis and screening of libraries of derivatives of therapeutically important classes of compounds such as benzodiazepines, prostaglandins and β-turn mimetics. In order to expediently synthesize a combinatorial library of derivatives based upon these core structures, general methodology for the solid phase synthesis of these derivatives is also provided. This disclosure thus also describes an important extension of solid phase synthesis methods to nonpolymeric organic compounds.
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- Synthesis and use of amino acid fluorides as peptide coupling reagents
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A compound of the formula STR1 or the acid fluoride salts thereof wherein BLK is an N-amino protecting group or hydrogenAA is an amino acid residue andX is H or a protecting group useful as a coupling agent in peptide synthesis.
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- METHOD OF TREATING DISORDERS OF THE DOPAMINERGIC SYSTEMS USING 2,5-DIAMINOTETRALINES
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The invention relates to novel 2,5-diaminotetralines of the formula: STR1 wherein R1, R2, R3 and R4 are defined herein, processes for preparing them and their use in pharmaceutical compositions. The novel 2, 5-diaminotetralines are useful in treating diseases caused by disorders of the dopaminergic systems.
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- 8 beta-substituted ergolines, process for their production and their use
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Compounds of formula I STR1 in which R2 means optionally substituted C1-7 alkyl, C2-7 alkenyl, CH2 --O--C1-4 alkyl or CH2 --S--C1-4 alkyl R6 means C2-6 alkyl, C3-6 alkenyl or C3-5 -cycloalkyl-C1-2 alkyl and R8 means CH2 --X, STR2 in which X stands for CN, OCH3, SCH3 or CONH2 and R1 stands for hydrogen, halogen, methyl or methoxy, and R3 and R4 each mean C1-4 alkyl or (CH2)n --N(CH3)2, in which n=1-4, and their acid addition salts, the process for their production, their use as pharmaceutical agents as well as intermediate compounds are described.
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