- Regioselective Alkylation of the Exocyclic Nitrogen of Heterocyclic Amidines via the Mitsunobu Reaction
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Regioselective alkylation of heterocyclic amidines by means of Mitsunobu reaction leads to L-aminoacid derivatives.
- Abarghaz, Mustapha,Kerbal, Abdelali,Bourguignon, Jean-Jacques
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- Nucleophilic heteroaromatic substitution: Kinetics of the reactions of nitropyridines with aliphatic amines in dipolar aprotic solvents
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Rate data are reported for the reactions of 2-chloro-5-nitropyridine 2a, 2-chloro-3-nitropyridine 2b, and the corresponding 2-phenoxy derivatives 2c with n-butylamine, pyrrolidine and piperidine and 2d with n-butylamine and pyrrolidine in dimethyl sulfoxi
- Isanbor, Chukwuemeka,Emokpae, Thomas A.
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- ONSH: Optimization of oxidative alkylamination reactions through study of the reaction mechanism
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(Figure presented) Oxidative alkylamination of electron-deficient (hetero)aromatic compounds, via the nucleophilic substitution of hydrogen, is a methodology that has made significant progress since the introduction of AgPy2MnO4 as oxidant. This oxidant generally gives good conversions and yields, whereas the use of KMnO4 only sometimes works equally well. In order to rationalize this, the reaction mechanism of oxidative alkylamination has been studied. 3-Nitropyridine (1), 1,3-dinitrobenzene (2), and quinazoline (3) were chosen as model substrates and n-butylamine and pyrrolidine as model alkylamines. The rate-limiting step of the mechanism for these substrate/alkylamine combinations was determined. With the use of 1H NMR spectroscopy thermodynamic properties of σ-- adduct formation were deduced and the effect of additives on the adduct formation was investigated. The fundamental insights resulting from these studies led to the identification of a cheap additive (tetrabutylammonium chloride), which in combination with the standard and cheap oxidant KMnO 4 generally gave excellent yields, similar to the ones previously obtained with more expensive AgPy2MnO4.
- Verbeeck, Stefan,Herrebout, Wouter A.,Gulevskaya, Anna V.,Van Der Veken, Benjamin J.,Maes, Bert U. W.
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experimental part
p. 5126 - 5133
(2010/09/18)
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- Practical amination of nitropyridones by silylation
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A practical method for coupling nitropyridones (1) with primary amines by treatment with hexamethyldisilazane has been developed, avoiding the use of hazardous reagents such as POCl3. The activation of the pyridone by a nitro group is necessary for efficient coupling, leading to aminonitropyridines (3) in good yields. Regioisomers other than 3-nitro-4-pyridone (1) were found to be substantially less reactive but would undergo coupling with primary amines.
- Singer, Robert A.,Dore, Michael
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supporting information
p. 1261 - 1264
(2013/01/03)
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- The effects of ring substituents and leaving groups on the kinetics of SNAr reactions of 1-halogeno- and 1-phenoxy-nitrobenzenes with aliphatic amines in acetonitrile
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Rate constants are reported for the reactions of a series of 1-chloro-, 1-fluoro- and 1-phenoxy-nitrobenzenes activated by CF3 or CN groups or by ring-nitrogen with n-butylamine, pyrrolidine or piperidine in acetonitrile. The results are compar
- Crampton, Michael R.,Emokpae, Thomas A.,Isanbor, Chukwuemeka
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p. 1378 - 1383
(2008/09/18)
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- C-N bond formation by the oxidative alkylamination of azines: Comparison of AgPy2MnO4 versus KMnO4 as oxidant
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Reports on the successful oxidative alkylamination of azines by the S NH-reaction, with the use of alkylamines other than methylamine, are very scarce. Hitherto, the experimental limitation to extend oxidative animation of azines wit
- Gulevskaya, Anna V.,Maes, Bert U. W.,Meyers, Caroline,Herrebout, Wouter A.,Van Der Veken, Benjamin J.
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p. 5305 - 5314
(2007/10/03)
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- Substitution reactions of 5-nitropyridine-2-sulfonic acid. A new pathway to 2,5-disubstituted pyridines
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We have investigated reactions of 5-nitropyridine-2-sulfonic acid and its potassium salt in which substitution of the sulfonate group by oxygen, nitrogen and halogen nucleophiles has been attempted. By this approach, 2-methoxy-(95% yield), 2-ethoxy- (97%), 2-isopropoxy- (65%), 2-amino- (92%), 2- butylamino- (76%), 2-diethylamino- (62%), 2-ethylamino- (32%), 2-benzylamino- (77%), 2-(R-1-phenylethylamino)- (71%) and 2-chloro-5-nitropyridine (87%) have been obtained. No reactions were observed with phenols or anilines. With t-BuOH, 2-hydroxy-5-nitropyridine was formed together with 2-methylpropene.
- Bakke, Jan M.,Sletvold, Ingrid
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p. 2710 - 2715
(2007/10/03)
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- The oxidative amination of 3-nitropyridines
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3-Nitropyridine was reacted with ammonia or alkylamines and KMnO4 under several different conditions. Substitutions in the para position to the nitro group were obtained with high regioselectivity: with ammonia, 2-amino-5-nitropyridine (66%), w
- Bakke, Jan M,Svensen, Harald
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p. 4393 - 4395
(2007/10/03)
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- 1H and 13C NMR Studies of Substituted Nitropyridines and Nitrobenzenes
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The 1H and 13C NMR spectra of 3-nitro-, 5-nitro- and 3,5-dinitro-2-methoxypyridines have been determined.The results show the preferred cis conformation for the 2-methoxy group, and the importance of steric repulsion between the oxygen atom of this group
- Nudelman, N. S.,Cerdeira, S. B.
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p. 507 - 511
(2007/10/02)
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