- Selective N-alkylation of indoles with α,β-unsaturated compounds catalyzed by a monomeric phosphate
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Catalytic N-alkylation of indoles is challenging because the N1 nitrogen atoms are inert toward electrophilic reagents. Herein, an organic-solvent- soluble alkylammonium salt of a simple monomeric phosphate ion, [PO 4]3-, with a high charge density acts as an efficient homogeneous catalyst for selective N-alkylation of indoles with α,β-unsaturated compounds. For the reaction of indole with ethyl acrylate, the turnover number reached up to 36 and the turnover frequency was 216 h-1; these values are the highest among those reported for base-mediated systems so far. In the presence of [PO4]3- ions, various combinations of nitrogen nucleophiles (ten examples) and α,β-unsaturated compounds (four examples) were efficiently converted to the desired N-alkylated products in high yields. NMR and IR spectroscopies showed formation of the indolyl anion through the activation of indole by the [PO4]3- ion, which plays an important role in the present N-alkylation.
- Sunaba, Hanako,Kamata, Keigo,Mizuno, Noritaka
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- Kinetic and scale-up investigations of a michael addition in microreactors
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Microreactors are an efficient tool for process development and intensification. However, the scale-up from lab studies to small-scale commercial production is challenging, since a change in the channel dimensions requires good knowledge of heat and mass transfer phenomena. In this work, complete process development for an exothermic Michael addition is presented. In a systematic scale-up approach, kinetic studies and experimental characterization of the employed reactors provide key parameters for detailed reactor modelling. The residence time distribution, reactant mixing, and removal of reaction heat are taken into account. It is exemplarily shown how preliminary experiments can be the basis for the prediction of scale-up effects and the development of a continuous production process. Plug flow behavior and short mixing times could be confirmed for all investigated flow reactors. Furthermore, interactions of reaction kinetics and the formation of hot spots in the reactor channel were investigated. For the examined reaction, the simulations predicted the product yield under production conditions in good accuracy.
- Schwolow, Sebastian,Heikenw?lder, Birgit,Abahmane, Lahbib,Kockmann, Norbert,R?der, Thorsten
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- Transition-metal-based Lewis acid catalysis of aza-type Michael additions of amines to α,β-unsaturated electrophiles in water
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Several transition-metal-based Lewis acid catalysts, especially FeCl 3 · 7 H2O, CrCl3 · 6 H 2O, and SnCl4 · 4 H2O, were shown to be highly effective for aza-type Michael reactions between electrophilic α,β-unsaturated compounds and both aliphatic and aromatic amines in aqueous solution. Advantages of the new protocol include 1) high-yielding reactions that can be conducted at ambient temperature; 2) the use of inexpensive, stable transition-metal salts as catalysts; and 3) plain H 2O as an environmentally benign solvent.
- Xu, Li-Wen,Li, Lyi,Xia, Chun-Gu
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- CATALYSIS OF THE SPECIFIC MICHAEL ADDITION : THE EXAMPLE OF ACRYLATE ACCEPTORS
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Lewis acids, ferric chloride in particular, catalyze the addition of amine nucleophiles to arcylates.Yields are very good, under mild conditions.Exlusive 1,4-addition occurs, and polymerization is avoided.
- Cabral, Jose,Laszlo, Pierre,Mahe, Loic,Montaufier, Marie-Therese,Randriamahefa, S. Lalatiana
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- Practical synthesis of natural amino acid derivatives: Hf(OTf) 4-catalyzed Mannich-type reaction of ketene silyl acetals or enol silyl ethers with N,O-acetals as a glycine cation equivalent
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The authors demonstrated the Hf(OTf)4-catalyzed Mannich-type reaction of an enol silyl ether and a ketene silyl acetal with an N,O-acetal leading to the preparation of amino acid derivatives. In particular, use of the N,O-acetal having a bis(tr
- Sakai, Norio,Sato, Asuka,Konakahara, Takeo
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- A basic ionic liquid as catalyst and reaction medium: A rapid and simple procedure for Aza-Michael addition reactions
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A fast, mild, and quantitative procedure for Michael addition reactions between various amines and α,β-unsaturated carbonyl compounds and nitriles in the presence of an easily accessible basic ionic liquid - 3-butyl-1-methylimidazolium hydroxide, [bmIm]OH - as both catalyst and reaction medium has been developed. For large-scale reactions the products could be directly distilled from the ionic liquid, allowing the use of organic solvents to be avoided totally. The ionic liquid could be reused at least eight times with consistent activity and was stable during the reaction process. Wiley-VCH Verlag GmbH & Co. KGaA, 2007.
- Xu, Jian-Ming,Wu, Qi,Zhang, Qing-Yi,Zhang, Fu,Lin, Xian-Fu
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- Rhodium(II) acetate catalyzed synthesis of cyclic enamides and enamines via β-hydride elimination
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A series of cylic diazoamides and diazoamines were synthesized. Treatment of these cylic diazoamides and diazoamines with a catalytic amount of rhodium(II) acetate furnished the corresponding cyclic enamides and enamines, respectively. Interestingly, cyclic diazoamines produced stereoselectively Z-enamines.
- Muthusamy, Sengodagounder,Gunanathan, Chidambaram,Babu, Srinivasarao Arulananda
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- Fast and Efficient Acquisition of Kinetic Data in Microreactors Using In-Line Raman Analysis
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This study demonstrates that a microreactor setup with fast in-line reaction monitoring by Raman spectroscopy can be a highly efficient laboratory tool for kinetic studies and process development. Using a coaxial probe and commercial spectrometer to perform real-time measurements in the microchannel prevents the need for reaction quenching, sampling, and time-consuming off-line analysis methods such as GC or HPLC. A specially designed, temperature-controlled aluminum plate microreactor was developed and tested in the exothermic synthesis of 3-piperidino propionic acid ethyl ester by Michael addition. In-line measurements through a fused quartz screen in the reactor channel, which had an increasing cross-sectional area, allowed time-series kinetic data to be collected over nearly the full range of reaction conversions. An optimum flow rate range in which nearly ideal plug flow behavior can be assumed was identified. Furthermore, a time gradient was applied to the reactant flow rates, and the product concentration was simultaneously and repeatedly measured at various locations in the reactor channel. With this approach, the experiment duration and material consumption are significantly reduced relative to those of conventional steady-state experiments. Two hundred data points with residence times ranging from 0.3 to 49 s were collected in less than 1 h. Thus, this method can be used for the high-throughput screening of reaction parameters in a microreactor.
- Schwolow, Sebastian,Braun, Frank,R?dle, Matthias,Kockmann, Norbert,R?der, Thorsten
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- A green and convenient approach for the one-pot solvent-free synthesis of coumarins and β-amino carbonyl compounds using Lewis acid grafted sulfonated carbon@titania composite
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Abstract: This paper reports an efficient protocol for the synthesis of coumarins via Pechmann reaction, and β-amino carbonyl compounds via aza-Michael reaction using catalytic amount of solid Lewis acid catalyst, C@TiO2–SO3–SbCl2. Six different catalysts were prepared by covalent immobilization of homogeneous Lewis acids onto sulfonated carbon@titania composite derived from amorphous carbon and nano-titania. Among various catalysts tested, C@TiO2–SO3–SbCl2 showed superior catalytic activity. The catalyst could be recycled without significant loss of its catalytic activity and demonstrated versatile catalysis for a wide range of substrates. Graphical abstract: [Figure not available: see fulltext.]
- Kour, Manmeet,Paul, Satya
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p. 327 - 337
(2017/02/10)
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- Nickel(II) N-Heterocyclic Carbene Complexes: Versatile Catalysts for C–C, C–S and C–N Coupling Reactions
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A variety of NiII complexes with a wide range of electronic and steric properties, bearing picolylimidazolidene ligands (a–g) and Cp (Cp = η5-C5H5; 2a–f) or Cp* (Cp* = η5-C5Me5; 3a, c, g) groups, have been synthesised and characterised by using NMR spectroscopy and single-crystal X-ray crystallography. The complexes have been used as precatalysts for a wide range of catalytic transformations, which most likely involve a Ni0/NiII catalytic cycle. In particular, the new well-defined 2a, 2c, 3a and 3c complexes have demonstrated great efficiency and versatility towards Suzuki–Miyaura coupling reactions, hydroamination of activated olefins and C–S cross-coupling reactions of aryl halides and thiols under mild conditions.
- Junquera, Lourdes Benítez,Fernández, Francys E.,Puerta, M. Carmen,Valerga, Pedro
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supporting information
p. 2547 - 2556
(2017/05/29)
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- Room temperature solvent free aza-Michael reactions over nano-cage mesoporous materials
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An efficient highly acidic three dimensional mesoporous aluminosilicate nano-cage material Al-KIT5, exhibited excellent catalytic activity in solvent free room temperature aza-Michael reactions of amines with α,β- unsaturated carbonyl compounds to produce β-amino carbonyl compounds with 100% product selectivity in a short reaction time. The high acidity, 3D pores, and a huge space in the nano-cages materials make them attractive candidate for carrying out important organic reactions. The catalyst provide a simple, easy to handle method, and could be used to solve the problems of corrosion, toxicity, waste production, and a high cost that are being currently encountered by the conventional homogeneous catalysts.
- Kalita, Pranjal,Pegu, Choitayna Dev,Dutta, Prantu,Baruah, Pranjal K.
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p. 145 - 150
(2014/08/18)
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- Titania nanoparticles stabilized HPA in SBA-15 for the intermolecular hydroamination of activated olefins
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A liquid phase hydroamination (HA) of α,β-ethylenic compounds with amines was investigated with TiO2 nanoparticles stabilized 12-tungstophosphoric acid (TPA) in SBA-15. The catalysts were prepared by wet impregnation of TPA/TiO2 nanoparticles into the SBA-15 and calcined at different temperatures. The characterization results reveal that the textural properties and the acidity of the prepared catalysts can be finely controlled with the simple adjustment of the calcination temperature and the structure of the support, decorated with the TiO2 and TPA nanoparticles, was intact even after the modification. The prepared catalysts were investigated for HA of ethyl acrylate with different aromatic and aliphatic amines over a wide range of reaction conditions to optimize the yield and the selectivity of product. It was found that this process is 100% atom efficient and the catalytic performance depended significantly on the loading of TPA over the catalyst and the calcination temperature. Under optimized reaction conditions, the best catalyst, 15 wt%TPA/22.4 wt%TiO2/SBA-15 calcined at 1123 K, offered the highest conversion of p-ethylaniline (70%) with 100% chemo-selectivity to the anti-Markovnikov product, i.e., the mono-addition product. The reaction was heterogeneously catalyzed and no contribution from leached TPA into the reaction was observed.
- Sawant-Dhuri, Dhanashri,Balasubramanian, Veerappan V.,Ariga, Katsuhiko,Park, Dae-Hwan,Choy, Jin-Ho,Cha, Wang Soo,Al-Deyab, Salem S.,Halligudi, Shivappa B.,Vinu, Ajayan
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p. 3347 - 3354
(2015/04/16)
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- Lipase-catalyzed aza-michael reaction on acrylate derivatives
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A methodology has been developed for an efficient and selective lipase-catalyzed aza-Michael reaction of various amines (primary and secondary) with a series of acrylates and alkylacrylates. Reaction parameters were tuned, and under the optimal conditions it was found that Pseudomonas stutzeri lipase and Chromobacterium viscosum lipase showed the highest selectivity for the aza-Michael addition to substituted alkyl acrylates. For the first time also, some CLEAs were examined that showed a comparable or higher selectivity and yield than the free enzymes and other formulations.
- Steunenberg, Peter,Sijm, Maarten,Zuilhof, Han,Sanders, Johan P. M.,Scott, Elinor L.,Franssen, Maurice C. R.
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p. 3802 - 3813
(2013/06/05)
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- Synthesis and characterization of N-substitutional ethylenediamine derivatives
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N-Substituted and N,N-disubstituted ethylenediamine derivatives were prepared rapidly in aqueous conditions from 30 to 76 % yields, respectively, on a multi-gram scale starting from inexpensive and commercially available starting materials. The steps involved Michael addition, hydrazinolysis and Curtius rearrangements. The highlight of this method lies on its convenience and economy in accessing these intermediates.
- Yao, Ri-Sheng,Jiang, Lai-En,Wu, Sheng-Hua,Deng, Sheng-Song,Yang, Yang
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experimental part
p. 3792 - 3794
(2012/01/05)
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- Cesium fluoride catalyzed Aza-Michael addition reaction in aqueous media
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A green approach to the Aza-Michael addition reaction between an amine and α,β-unsaturated compounds has been achieved by conventional as well as non-conventional methods. The reaction is catalyzed by cesium fluoride (CsF) in aqueous media at ambient temperature to afford the product in excellent yield. Ultrasound irradiation has been used as a non-conventional energy source, which reduces the reaction time with improved product yield.
- Labade, Vilas B.,Pawar, Shivaji S.,Shingare, Murlidhar S.
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experimental part
p. 1055 - 1059
(2012/07/27)
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- Crown ether complex cation ionic liquids: Preparation and applications in organic reactions
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A series of crown ether complex cation ionic liquids (CECILs) were designed, synthesised and characterised by NMR spectroscopy, HRMS, thermogravimetric differential thermal analysis (TG-DTA) and elemental analysis. Their applications in various organic reactions were investigated: [15-C-5Na][OH], [15-C-5Na][OAc], [18-C-6K][OH] and [18-C-6K][OAc] (15-C-5=[15]crown-5; 18-C-6=[18]crown-6) efficiently catalysed the Michael addition of alkenes and relevant nucleophiles; [18-C-6K][OH] and [15-C-5Na][OH] effectively catalysed the Henry reaction of nitromethane and aromatic aldehydes; [18-C-6K][OH] has excellent catalytic efficiency for Knoevenagel condensation of aromatic aldehydes and malononitrile; PdCl2/[18-C-6K] 3[PO4]/K2CO3 efficaciously catalysed the Heck reaction of olefins and aromatic halides; [18-C-6K][BrO3] can be used as both oxidant and solvent in the oxidation reaction of aromatic alcohols. The CECIL catalysts [15-C-5Na][OH] (Michael addition) and [18-C-6K][OH] (Henry reaction) can be recycled and reused several times without obvious loss of activity and their recovery is very simple.
- Song, Yingying,Jing, Huanwang,Li, Bo,Bai, Dongsheng
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experimental part
p. 8731 - 8738
(2011/09/16)
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- N-donor ligand as catalyst: A simple Aza-Michael addition reaction in aqueous media
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(Chemical Equation Presented) A novel approach for the Aza-Michael addition reactions between various amines and α,β-unsaturated esters, nitriles and ketones using N-donor Ligand catalyst (3 mol %) is described. The reactions are carried out in aqueous media at an ambient temperature to afford the products in excellent yields.
- Pawar, Shivaji S.,Dekhane, Deepak V.,Shingare, Murlidhar S.,Thore, Shivaji N.
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experimental part
p. 1869 - 1873
(2009/06/18)
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- Cerium(IV) ammonium nitrate (CAN) catalyzed aza-Michael addition of amines to α,β-unsaturated electrophiles
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Cerium(IV) ammonium nitrate (CAN) catalyzed facile and efficient aza-Michael addition of aromatic and aliphatic amines with α,β-unsaturated electrophiles in the absence of solvent under ultrasound irradiation.
- Duan, Zheng,Xuan, Xuejie,Li, Ting,Yang, Chenfei,Wu, Yangjie
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p. 5433 - 5436
(2007/10/03)
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- Ceric ammonium nitrate catalyzed aza-Michael addition of aliphatic amines to α,β-unsaturated carbonyl compounds and nitriles in water
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Ceric ammonium nitrate (3 mol%) efficiently catalyzes the aza-Michael reaction of amines with α,β-unsaturated carbonyl compounds in water to produce the corresponding β-amino carbonyl compounds in good to excellent yields (55-99%) for most of the compounds under mild conditions. The reaction is procedurally simple and displays limited chemoselectivity, as aromatic amines were found to be unreactive. Georg Thieme Verlag Stuttgart.
- Varala, Ravi,Sreelatha, Nuvula,Adapa, Srinivas R.
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p. 1549 - 1553
(2007/10/03)
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- Addition of secondary amines to α,β-unsaturated carbonyl compounds and nitrites by using microstructured reactors
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Several additions of amines to α,β-unsaturated carbonyl compounds (Michael additions) were performed in a continuous-flow microstructured reactor rig and compared to the respective batch reaction. Dimethylamine/diethylamine/piperidine and acrylic acid ethyl ester/acrylonitrile were employed as two sets of reactants, giving six reactions. Some of these reactions are highly exothermal. Using the traditional batch procedure the olefin must be added quite slowly to the diluted amine to ensure temperature control and safe operation; especially this is necessary for the addition of dimethylamine (40 mass % aqueous solution) to acrylonitrile. Good yields (>85%) are achieved in this way; however, processing time is very long (17-25 h). To reveal the intrinsic kinetic potential and thus to accelerate these reactions, the reactants were mixed in a continuous-flow microstructured reactor rig which allows rapid mixing and efficient removal of the reaction heat. In this way, reaction time was decreased to a few seconds up to about half an hour, which is a change by 2 orders of magnitude. While the yields achieved with the continuous-flow microstructured reactor rig matched those for the batch procedure, the space-time yields for the microflow processing are much higher, in the best case by a factor of about 650.
- Loewe,Hessel,Lob,Hubbard
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p. 1144 - 1152
(2012/12/23)
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- Ultrasound-irradiated Michael addition of amines to ferrocenylenones under solvent-free and catalyst-free conditions at room temperature
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A facile Michael addition of ferrocenylenones with aliphatic amines under ultrasound irradiation in the absence of solvent and catalyst at room temperature can afford 1-ferrocenyl-3-amino carbonyl compounds rapidly in high yields, which is also efficient in the aza-Michael reaction of other α,β-unsaturated carbonyl compounds such as chalcone, carboxylic ester, etc. However, aromatic amines do not undergo the conjugate addition at all, and the reactions under existing methods do not proceed or take place in low yield after a long reaction time. Apart from experimental simplicity, generality and selectivity, the advantages of this methodology are the rapid, environmentally benign and less expensive processes, which will contribute to the progress of green chemistry.
- Yang, Jin-Ming,Ji, Shun-Jun,Gu, Da-Gong,Shen, Zhi-Liang,Wang, Shun-Yi
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p. 2989 - 2995
(2007/10/03)
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- RuCl3 in poly(ethylene glycol): A highly efficient and recyclable catalyst for the conjugate addition of nitrogen and sulfur nucleophiles
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The 1,4-conjugate addition of primary, secondary and aromatic amines, thiols, and carbamate to α,β-unsaturated compounds mediated by a catalytic amount (0.5 mol%) of RuCl3 in poly(ethylene glycol) (PEG) provides the desired β-substituted carbonyls in high yields. In particular, we found that primary aliphatic and aromatic amines produced the single adducts as the sole products in very high yields with RuCl3-PEG. RuCl 3-PEG was readily recycled via solvent precipitation with efficient recyclability as evidenced by high yields. Its properties of low sensitivity toward moisture and oxygen, high tolerance of different functional groups, and efficient recyclability make RuCl3-PEG suitable for both laboratory and industrial scale synthesis of β-substituted carbonyls. Georg Thieme Verlag Stuttgart.
- Zhang, Huaxing,Zhang, Yuhong,Liu, Leifang,Xu, Hailiang,Wang, Yanguang
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p. 2129 - 2136
(2007/10/03)
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- Structure-activity relationship of trihexyphenidyl analogs with respect to the dopamine transporter in the on going search for a cocaine inhibitor
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A series of trihexyphenidyl (THP) analogs were used to search for a derivative that could serve as a cocaine inhibitor. A compound that blocks binding of the cocaine analog carboxyfluorotropane (CFT), allows dopamine uptake and exhibits low side effects could serve as a good candidate for that purpose. All analogs were tested for the extent to which they inhibit CFT binding, dopamine uptake and n-methyl scopolamine (NMS) binding. Several structure-function relationships emerged. Methylation/halogenation of THP's benzene ring enhanced the compound's ability to block CFT binding in comparison to its ability to block dopamine uptake (5a-e). Replacement of the cyclohexyl ring with a benzene ring tended to create compounds that had lower affinities to the dopamine transporter (7b compared to THP, 7d compared to 5h, 7c compared to 8c) and modification of THP's piperidine ring tended to enhance affinity to the dopamine transporter (5f-h, 8a, 8c). One analog (5f) that showed little muscarinic activity indicating that it would probably have few side effects was investigated for its effects as an in vivo cocaine inhibitor. However, it showed few antagonistic effects in vivo. Nevertheless, this work greatly elucidates the structure-function relationships required for potential cocaine inhibitors and so lays out promising directions for future research.
- Dar,Thiruvazhi,Abraham,Kitayama,Kopajtic,Gamliel,Slusher,Carroll,Uhl
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p. 1013 - 1021
(2007/10/03)
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- A green, ionic liquid and quaternary ammonium salt-catalyzed aza-Michael reaction of α,β-ethylenic compounds with amines in water
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The first environmentally benign, highly efficient conjugate addition of aliphatic amines to α,β-unsaturated compounds catalysed by simple quaternary ammonium salts and ionic liquids in the green solvent, water, is described.
- Xu, Li-Wen,Li, Jing-Wei,Zhou, Shao-Lin,Xia, Chun-Gu
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p. 183 - 184
(2007/10/03)
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- Water promoted Michael addition of secondary amines: To α,β- unsaturated carbonyl compounds under microwave irradiation
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A rapid Michael addition of secondary amines to α,β-unsaturated carbonyl compounds has been achieved in good to excellent yields in the presence of water under microwave irradiation. In the absence of water and under conventional method the reaction does not proceed or take place in very low yield after a long reaction time.
- Matloubi Moghaddam, Firouz,Mohammadi, Mohsen,Hosseinnia, Azarmidocht
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p. 643 - 650
(2007/10/03)
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- Aqueous basicity and proton affinity of zwitterionic ω-(N-methylpiperidine)-alkanocarboxylates and ω-(N-piperidine)-alkanocarboxylic acids
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The pK a values of 5 ω-(N-methylpiperidine)-alkanocarboxylates (N-methylpiperidine betaines) and 5 ω-(N-piperidine)-alkanocarboxylic acid were determined by potentiometric titration of their hydrohalides with KOH. Semiempirical geometry optimizations were performed for gaseous betaines. Four conformers were characterized and their PA values estimated. The PA values fulfilled the linear correlation with the aqueous pKa values estimated in ref. 1. A linear correlation between the calculated heat of formation (ΔHt) and the sum of the N...O1 and N...O2 distances, for the conformers containing the same number of CH2 groups, indicates that they are stabilized by the intramolecular electrostatic interactions between the positively charged nitrogen atom and oxygen atoms of the carboxylate group.
- Barczynski,Dega-Szafran,Dulewicz,Petryna,Szafran
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p. 1149 - 1161
(2007/10/03)
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- Syntheses des alkyl-1 cyclanols fonctionnalises aux positions α, β et γ de la chaine hydrocarbonee
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We have developed a general and versatile synthesis of N,N-dialkylaminoalkyl-, 1-chloroalkyl-, 1-phenoxyalkyl-, 1-thiophenoxyalkyl-, 1-diethoxyalkyl-, and 1-(1,3-dithiolane)alkylcyclanols in good yields by the reaction of α,ω-bis(bromomagnesio)alkanes with the corresponding functionalized carboxylic acid esters.
- Canonne, P.,Belley, M.,Fytas, G.,Plamondon, J.
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p. 168 - 173
(2007/10/02)
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