- Robust Cobalt Catalyst for Nitrile/Alkyne [2+2+2] Cycloaddition: Synthesis of Polyarylpyridines and Their Mechanochemical Cyclodehydrogenation to Nitrogen-Containing Polyaromatics**
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The transition-metal-catalyzed [2+2+2] cycloaddition of nitriles and alkynes is an established synthetic approach to pyridines; however, these cycloadditions often rely on the use of tethered diynes or cyanoalkynes as one of the reactants. Thus, examples of efficient, fully intermolecular catalytic [2+2+2] pyridine synthesis, especially those employing unactivated nitriles and internal alkynes leading to pentasubstituted pyridines, remain scarce. Herein, we report on simple and inexpensive catalytic systems based on cobalt(II) iodide, 1,3-bis(diphenylphosphino)propane, and Zn that promote [2+2+2] cycloaddition of various nitriles and diarylacetylenes for the synthesis of a broad range of polyarylated pyridines. DFT studies support a reaction pathway involving oxidative coupling of two alkynes, insertion of the nitrile into a cobaltacyclopentadiene, and C-N reductive elimination. The resulting tetra- and pentaarylpyridines serve as precursors to hitherto unprecedented nitrogen-containing polycyclic aromatic hydrocarbons via mechanochemically assisted multifold reductive cyclodehydrogenation.
- Wang, Chang-Sheng,Sun, Qiao,García, Felipe,Wang, Chen,Yoshikai, Naohiko
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supporting information
p. 9627 - 9634
(2021/03/19)
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- N-Silylenamines as Reactive Intermediates: Hydroamination for the Modular Synthesis of Selectively Substituted Pyridines
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A modular and selective synthesis of mono-, di-, tri-, tetra-, and pentasubstituted pyridines is reported. Hydroamination of alkynes with N-silylamine using a bis(amidate)bis(amido)titanium(IV) precatalyst furnishes the regioselective formation of N-silylenamines. Addition of α,β-unsaturated carbonyls to the crude mixtures followed by oxidation affords 47 examples of pyridines in yields of up to 96%. This synthetic route allows for the synthesis of diverse pyridines containing variable substitution patterns, including pharmaceutically relevant 2,4,5-trisubstituted pyridines, using this one-pot protocol.
- Lui, Erica K. J.,Hergesell, Daniel,Schafer, Laurel L.
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supporting information
p. 6663 - 6667
(2018/11/21)
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- Convenient synthesis of selected meta- and ortho-substituted pentaarylpyridines via the Suzuki-Miyaura cross-coupling reaction
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The first synthesis of sterically demanding, stable at room temperature atropisomeric derivatives of penta-(ortho-substituted phenyl)pyridines is described. The Suzuki-Miyaura cross-coupling reaction of pentabromopyridine and selected meta- and ortho-tolylboronic acids afforded a series of pentaarylpyridine derivatives. The structures of two room temperature stable atropisomeric derivatives of penta-(o-tolyl)pyridines were confirmed by single-crystal X-ray analysis. Racemic atropisomers were examined by1H NMR spectroscopy with a chiral solvating agent in order to visualize the presence of individual enantiomers.
- Pomarański, Piotr,Roszkowski, Piotr,Maurin, Jan K.,Budzianowski, Armand,Czarnocki, Zbigniew
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p. 462 - 465
(2017/01/10)
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- A general protocol for the efficient synthesis of polyarylated benzenes by multiple Suzuki-Miyaura reactions of polychlorinated benzenes
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A general protocol for the highly efficient synthesis of polyarylated benzene derivatives by multiple Suzuki-Miyaura reactions of polychlorinated benzenes was developed. Using bulky and electron-rich phosphine ligands, up to quantitative yields of the desired compounds were achieved. Moreover, the reactions show good functional group tolerance and allow the employment of sterically demanding boronic acids.
- Reimann, Sebastian,Ehlers, Peter,Sharif, Muhammad,Spannenberg, Anke,Langer, Peter
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p. 1083 - 1094
(2016/07/06)
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- Site selective synthesis of pentaarylpyridines via multiple Suzuki-Miyaura cross-coupling reactions
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Pentaarylpyridines were conveniently prepared in one step by pentafold Suzuki-Miyaura reactions of pentachloropyridine. Moreover, site selective reactions were performed, leading to various substituted arylpyridines. Pentaarylpyridines were studied in det
- Reimann, Sebastian,Ehlers, Peter,Petrosyan, Andranik,Kohse, Stefanie,Spannenberg, Anke,Surkus, Annette E.,Ghochikyan, Tariel V.,Saghyan, Ashot S.,Lochbrunner, Stefan,Kuehn, Oliver,Ludwig, Ralf,Langer, Peter
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p. 1987 - 2008
(2014/07/07)
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- (η3-Allyl)(η5-pentamethylcyclopentadienyl)cobalt - a Selective Catalyst for the Pyridine Synthesis
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(η3-Allyl)(η5-pentamethylcyclopentadienyl)cobalt (1) cactalyses the synthesis of various pyridines from alkynes and nitriles under mild conditions.Only small amounts of benzenes are formed in this selective reaction. - Key Words: Cobalt complexes, (η3-allyl)(η5-pentamethylcyclopentadienyl)- / Pyridine synthesis / Catalytic activity / Chemoselectivity
- Nehl, Hans
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p. 2535 - 2538
(2007/10/02)
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- ETUDE DE LA REACTIVITE DE L'ION AZTURE VIS A VIS DE CATIONS HETEROCYCLIQUES-III REARRANGEMENTS THERMIQUES ET PHOTOCHIMIQUES DES AZIDES COVALENTS RESULTANT DE L'ION AZOTURE SUR DES CATIONS PYRYLIUM ET THIOPYRYLIUM DIVERSEMENT SUBSTITUES. NOUVEL ACCES A DES HETEROAZEPINES
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Azidopyrans rearrange at room temperature to 1,3-oxazepins but azidothiopyrans need heating to form unstable thiazepins. these intermediate thiazepins give the competitive formation of the corresponding pyridines after sulphur extrusion or of the corresponding thiophens after elimination of benzonitrile. Photochemical attempts to obtain thiazepins from azidothiopyrans were unsuccessful.
- Desbene, P.-L.,Cherton, J.-C.
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p. 3559 - 3565
(2007/10/02)
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- Kinetics and Mechanism of the C-Alkylation of Nitroalkane Anions by 1-Alkyl-2,4,6-triphenylpyridiniums: A Nonchain Reaction with Radicaloid Characteristics
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The C-alkylation of 2-nitropropanide by N-substituted pyridiniums is first order in each reactant in Me2SO.The effect on the rate of temperature , N substituent, leaving group, and nucleophile was studied quantitatively.Overall, the evidence excludes an SN2 displacement and suggests that the reactions proceed by a free radical nonchain mechanism.
- Katritzky, Alan R.,Kashmiri, M. Akram,Ville, George Z. de,Patel, Ranjan C.
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- Improved Methods for Conversion of Primary Amines into Bromides
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N-Alkyl- and N-benzyl-4-p-chlorophenyl-2,3,5,6-tetraphenyl- N-alkyl- and N-benzyl-2,3,4,5,6-pentaphenyl-, and N-alkyl- and N-benzyl-2,4,6-triphenyl-pyridinium bromides on pyrolysis at 180-220 deg C give the corresponding alkyl and benzyl bromides in high yield. 1-Benzyl-5,6-dihydro-2,4-diphenylbenzoquinolinium trifluoromethanesulphonate gave benzyl bromide on heating with KBr in dimethylformamide at 100 deg C, and n-octyl bromide (80percent) was obtained from the corresponding pentacyclic bromide in refluxing acetonitrile.
- Katritzky, Alan R.,Al-Omran, Fatima,Patel, Ranjan C.,Thind, Sukhpal S.
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p. 1890 - 1894
(2007/10/02)
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