19653-33-9Relevant articles and documents
Selective N-alkylation of indoles with α,β-unsaturated compounds catalyzed by a monomeric phosphate
Sunaba, Hanako,Kamata, Keigo,Mizuno, Noritaka
, p. 2333 - 2338 (2014)
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.
Kinetic and scale-up investigations of a michael addition in microreactors
Schwolow, Sebastian,Heikenw?lder, Birgit,Abahmane, Lahbib,Kockmann, Norbert,R?der, Thorsten
, p. 1535 - 1544 (2014)
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.
Transition-metal-based Lewis acid catalysis of aza-type Michael additions of amines to α,β-unsaturated electrophiles in water
Xu, Li-Wen,Li, Lyi,Xia, Chun-Gu
, p. 1522 - 1526 (2004)
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.
CATALYSIS OF THE SPECIFIC MICHAEL ADDITION : THE EXAMPLE OF ACRYLATE ACCEPTORS
Cabral, Jose,Laszlo, Pierre,Mahe, Loic,Montaufier, Marie-Therese,Randriamahefa, S. Lalatiana
, p. 3969 - 3972 (1989)
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.
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
Sakai, Norio,Sato, Asuka,Konakahara, Takeo
, p. 1449 - 1452 (2009)
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
A basic ionic liquid as catalyst and reaction medium: A rapid and simple procedure for Aza-Michael addition reactions
Xu, Jian-Ming,Wu, Qi,Zhang, Qing-Yi,Zhang, Fu,Lin, Xian-Fu
, p. 1798 - 1802 (2007)
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.
Rhodium(II) acetate catalyzed synthesis of cyclic enamides and enamines via β-hydride elimination
Muthusamy, Sengodagounder,Gunanathan, Chidambaram,Babu, Srinivasarao Arulananda
, p. 471 - 474 (2002)
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.
Fast and Efficient Acquisition of Kinetic Data in Microreactors Using In-Line Raman Analysis
Schwolow, Sebastian,Braun, Frank,R?dle, Matthias,Kockmann, Norbert,R?der, Thorsten
, p. 1286 - 1292 (2015)
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.
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
Kour, Manmeet,Paul, Satya
, p. 327 - 337 (2017/02/10)
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.]
Nickel(II) N-Heterocyclic Carbene Complexes: Versatile Catalysts for C–C, C–S and C–N Coupling Reactions
Junquera, Lourdes Benítez,Fernández, Francys E.,Puerta, M. Carmen,Valerga, Pedro
supporting information, p. 2547 - 2556 (2017/05/29)
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.
