- Reversible C-N Bond Formation in the Zirconium-Catalyzed Intermolecular Hydroamination of 2-Vinylpyridine
-
The intermolecular hydroamination of alkenes with alkylamines has been a long-standing challenge in catalysis, partially due to the near-thermoneutral nature of this transformation. Consistent with this understanding, we report the direct observation of reversible C-N bond formation in hydroamination. A bis(ureate) zirconium complex catalyzed the intermolecular hydroamination of 2-vinylpyridine. Reversible C-N bond formation was characterized by variable-temperature NMR spectroscopy, and thermodynamic parameters were determined using van't Hoff plots. Isolated intermediates support an aza-Michael-addition mechanism. Sensitivity to steric bulk in the C-N bond forming step provided further evidence for the kinetically accessible but limited thermodynamic driving force for this transformation.
- Griffin, Samuel E.,Pacheco, Javier,Schafer, Laurel L.
-
-
Read Online
- The catalytic effect of anion-exchanged supported ionic liquid on aza-Michael-type addition
-
Abstract: An effective synthesis of anion-exchanged supported ionic liquids using diatomaceous earth as solid support and its catalytic effect on the aza-Michael-type addition is described. Anionic polytungstophosphate and bisulfate ion are used in the anion-exchange step in catalyst design. In addition, the aza-Michael-type addition of various amines to 2- and 4-vinyl pyridine was examined in this article. The catalytic system can be separated from the reaction mixture and recycled in subsequent reactions. The structure of anion-exchanged supported ionic liquid on diatomaceous earth was studied by XRD, FT-IR, SEM, TGA and BET techniques. The structure of organic products was determined by 1HNMR, 13CNMR, FTIR, CHN and MASS spectroscopy. Graphical Abstract: [Figure not available: see fulltext.].
- Ghasemi, Mohammad Hadi,Kowsari, Elaheh
-
p. 3691 - 3709
(2017/06/20)
-
- Aza-Michael-type addition reaction catalysed by a supported ionic liquid phase incorporating an anionic heteropoly acid
-
In this work, we have obtained substituted amines under mild conditions in good yields using the Aza-Michael-type addition of various amines to vinyl compounds catalysed by a supported ionic liquid incorporating an anionic heteropoly acid. Different catalysts, including Lewis acids, Br?nsted acids and heteropoly acids were investigated in which heteropoly acids having dual Br?nsted and Lewis acid characteristics were excellent catalysts. The ionic liquid incorporating a polytungstate anion supported on magnetic diatomaceous earth as a magnetically separable heterogeneous catalyst offered the best results in terms of yield. The solid nanocatalyst was easily removed with a magnet.
- Ghasemi, Mohammad Hadi,Kowsari, Elaheh,Shafiee, Abbas
-
supporting information
p. 1150 - 1153
(2016/03/09)
-
- Lewis acid activation of pyridines for nucleophilic aromatic substitution and conjugate addition
-
A clean, mild and sustainable method for the functionalization of pyridines and their analogues is reported. A zinc-based Lewis acid is used to activate pyridine and its analogues towards nucleophilic aromatic substitution, conjugate addition, and cyclization reactions by binding to the nitrogen on the pyridine ring and activating the pyridine ring core towards further functionalization.
- Abou-Shehada, Sarah,Teasdale, Matthew C.,Bull, Steven D.,Wade, Charles E.,Williams, Jonathan M. J.
-
p. 1083 - 1087
(2015/03/30)
-
- Photocatalyzed [2 + 2 + 2]-cycloaddition of nitriles with acetylene: An effective method for the synthesis of 2-pyridines under mild conditions
-
The photocatalyzed [2 + 2 + 2]-cycloaddition of nitriles with 2 equiv of acetylene to 2-pyridines can be carried out under mild conditions and represents a valuable extension to common synthetical methods. For the ideal wavelength range (350-500 nm), lamps as well as sunlight can be used. Working at room temperature and in organic solvents such as toluene or hexane as well as in water gives satisfying results in many cases. However, it is also possible to vary the solvent and the reaction temperature of the photocatalyzed synthesis and to choose, with respect to the specific substrate, specific requirements for this particular reaction and general requirements of the method. This simple and selective method derives its potential mainly from the large variety of applicable nitriles. Suitable substrates include (functionalized) aliphatic and aromatic nitriles as well as cyanamides derived from secondary amines.
- Heller, Barbara,Sundermann, Bernd,Buschmann, Helmut,Drexler, Hans-Joachim,You, Jingsong,Holzgrabe, Ulrike,Heller, Eberhard,Oehme, Guenther
-
p. 4414 - 4422
(2007/10/03)
-
- Anti-Markonikov reactions, 6. Rhodium-catalyzed amination of vinylpyridines: Hydroamination versus oxidative amination
-
Cationic rhodium complexes catalyze the amination of 2- and 4- vinylpyridine with secondary amines. Depending on the substrate and the reaction conditions either oxidative amination to yield the corresponding enamines 1a-8a or hydroamination to give 2-aminoethylpyridines 1b-8b occurs. In all cases products with anti-Markovnikov regioselectivity are obtained. For mechanistic studies novel cationic complexes of rhodium(I)-containing cyclooctadiene and vinylpyridine 12 as well as complexes containing cyclooctadiene, vinylpyridine, and morpholine 13 were prepared and characterized by NMR spectroscopy and X-ray diffraction analysis.
- Beller, Matthias,Trauthwein, Harald,Eichberger, Martin,Breindl, Claudia,Mueller, Thomas E.
-
p. 1121 - 1132
(2007/10/03)
-
- SYNTHESIS OF FUNCTIONALLY SUBSTITUTED PYRIDINES AND DIPYRIDYL-SUBSTITUTED COMPOUNDS WITH THE AID OF LOW-VALENCE COMPOLEXES
-
The possibility of the preparation of oxygen, nitrogen, and sulfur-containing pyridines and dipyridyl-substituted compounds by the cyclocotrimerization of substituted propionitriles with acetylene under the influence of a Co(2-ethylhexanoate)2-Al(C2H5)3 catalyst was demonstrated.It was established that the nature of the heteroatom in substituted propionitriles has virtually no effect on the direction of the reaction.
- Selimov, F. A.,Khafizov, V. R.,Dzhemilev, U. M.
-
p. 290 - 295
(2007/10/02)
-