- Redox Property of Enamines
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Enamines are electron-rich compounds bearing intriguing redox properties. Herein, a series of secondary enamines condensed from primary amine and β-ketocarbonyls were synthesized and their electrochemical oxidation properties were systematically studied by cyclic voltammetry. Furthermore, theoretical calculation of oxidation potentials of enamines, particularly those catalytic intermediates, was also conducted to further broaden the scope investigated. Possible structural factors on oxidation and the nature of the resulted radical cation intermediates were revealed and discussed. Correlation of redox potentials with molecular properties such as highest occupied molecular orbital energies and natural population analysis charge were explored, and there appears no simple linear correlation. On the other hand, a good correlation with Mayr's nucleophilicity parameter N was noted among a range of catalytically relevant enamines. Spin population analysis disclosed that enamine radical cations mainly exhibit the carbon-center free radical feature. Taking experimental and computation data together, a comprehensive picture about the redox property of enamines is presented, which would provide guidance in the development of oxidative enamine catalysis and transformations.
- Li, Yao,Wang, Dehong,Zhang, Long,Luo, Sanzhong
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p. 12071 - 12090
(2019/10/11)
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- Visible Light Promoted β-C—H Alkylation of β-Ketocarbonyls via a β-Enaminyl Radical Intermediate
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A 5πe carbonyl activation mode is reported on the basis of photo-induced single-electron-transfer (SET) oxidation of a secondary enamine. The resultant β-enaminyl radical intermediate was trapped by a wide range of Michael acceptors, producing β-alkylation products of β-ketocarbonyls in a highly efficient manner.
- Wang, Dehong,Zhang, Long,Luo, Sanzhong
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p. 311 - 320
(2018/02/21)
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- Cyanuric chloride catalysed rapid conversion of β-ketoesters into β-enaminoesters under mild and solvent-free conditions
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Cyanuric chloride is shown to be an extremely efficient catalyst for the synthesis of β-enaminoesters from β-ketoesters under solvent-free conditions by grinding in a mortar with pestle at 25 °C. A short reaction time, an inexpensive and easily available catalyst, mild reaction conditions and excellent yields of the products are attractive features of this methodology.
- Kamble,Joshi,Atkore
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experimental part
p. 616 - 621
(2012/07/03)
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- Stereodefined homopropargyl amines by tandem nucleophilic addition/fragmentation of dihydropyridone triflates
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Dihydropyridone (DHPD) triflates undergo nucleophile-triggered fragmentation to provide homopropargyl amine derivatives, the stereochemistry of which is defined by starting from readily available β-amino esters.
- Tummatorn, Jumreang,Dudley, Gregory B.
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supporting information; experimental part
p. 158 - 160
(2011/03/20)
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- Ni(OAc)2: A highly efficient catalyst for the synthesis of enaminone and enamino ester derivatives under solvent-free conditions
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Ni(OAc)2 was found to be an efficient catalyst for the synthesis of β-enamino ketones or esters from β-dicarbonyl compounds and amines under solvent-free conditions. The reusability of the catalyst was successfully examined without noticeable loss of its catalytic activity. Copyright
- Liu, Ju-Yan,Cao, Gai-E.,Xu, Wei,Cao, Jie,Wang, Wei-Lu
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experimental part
p. 685 - 691
(2010/11/20)
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- P2O5/SiO2 as a new, efficient, and reusable catalyst for preparation of β-enaminones under solvent-free conditions
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P2O5/SiO2 (30% w/w) was applied as an efficient, heterogeneous, and reusable catalyst for the synthesis of β-enaminones. The reactions were rapidly completed at 80°C under solvent-free conditions and products were obtained in good to excellent yields. Copyright Taylor & Francis Group, LLC.
- Mohammadizadeh, Mohammad R.,Hasaninejad,Bahramzadeh,Khanjarlou, Z. Sardari
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experimental part
p. 1152 - 1165
(2009/10/09)
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- General, mild and efficient synthesis of β-enaminones catalyzed by ceric ammonium nitrate
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Ceric ammonium nitrate catalyzes the reaction between aromatic or aliphatic primary amines and a variety of β-dicarbonyl compounds, including β-ketoesters, β-ketothioesters and β-diketones. The reaction proceeds smoothly at room temperature in short react
- Sridharan, Vellaisamy,Avenda?o, Carmen,Menéndez
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p. 881 - 884
(2008/02/02)
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- Enamination of 1,3-dicarbonyl compounds catalyzed by tin tetrachloride
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Tin tetrachloride has been found to be an extremely efficient catalyst for the enamination of 1,3-dicarbonyl compounds under solvent-free conditions at room temperature.
- Zhang, Zhan-Hui,Ma, Zi-Chuan,Mo, Li-Ping
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p. 535 - 539
(2008/09/18)
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- Phosphotungstic acid catalysed synthesis of β-enamino compounds under solvent-free conditions
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A convenient eco-friendly procedure has been developed for the synthesis of β-enaminones and β-enamino esters by reacting 1,3-dicarbonyl compounds with amines in the presence of catalytic amounts of phosphotungstic acid (H3PW12O40,1 mol%). The reaction proceeds smoothly at room temperature under solvent-free conditions and gives the corresponding β-enamino compounds in high to excellent yields.
- Li, Geng-Chen
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p. 696 - 698
(2008/09/20)
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- ZrCl4-catalyzed efficient synthesis of enaminones and enamino esters under solvent-free conditions
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A facile synthesis of β-enaminones and enamino esters by condensation of β-dicarbonyl compounds with differently substituted amines in the presence of ZrCl4 under solvent-free conditions is reported.
- Lin, Jin,Zhang, Li-Feng
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- An efficient method for the enamination of 1,3-dicarbonyl compounds with ceric ammonium nitrate (CAN)
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An efficient method for the enamination of 1,3-dicarbonyl compounds by employing ceric ammonium nitrate (CAN) as the catalyst has been described. A variety of β-amino-α,β-unsaturated ketones and esters have been synthesized in excellent yield within a short reaction time under solvent-free conditions.
- Mo, Li-Ping,Liu, Shu-Fen,Li, Wan-Zhi
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p. 879 - 884
(2008/02/11)
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- A general and efficient method for the preparation of β-enamino ketones and esters catalyzed by indium tribromide
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A variety of β-enamino ketones and esters have been synthesized in high to exellent yields by reacting β-dicarbonyl compounds with amines in the presence of a catalytic amount of indium tribromide. The reaction proceeds smoothly at room temperature in a short reaction time under solvent-free conditions.
- Zhang, Zhan-Hui,Yin, Liang,Wang, Yong-Mei
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p. 184 - 190
(2007/10/03)
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- Regio- and stereoselective double alkylation of β-enamino esters with organolithium reagents followed by one-pot reduction: convenient method for the synthesis of tertiary γ-amino alcohols
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An easy, high yielding and stereoselective procedure for the preparation of tertiary γ-amino alcohols starting from β-enamino esters is presented. In this procedure, the double alkylation of β-enamino esters with organolithium reagents is followed by one-
- Cimarelli, Cristina,Palmieri, Gianni,Volpini, Emanuela
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p. 9423 - 9432
(2007/10/03)
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- Efficient synthesis of β-aminoacrylates and β-enaminones catalyzed by Zn(OAc)2·2H2O
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The direct condensation of amines with β-ketoesters and β-diketones to produce functional enamine derivatives has been investigated with zinc Lewis acid catalysts. Zn(OAc)2·2H2O shows good catalytic activity and leads to a chemo- and stereoselective formation of (Z)-enamine derivatives from aliphatic primary amines and ring-substituted anilines under mild conditions.
- Vohra, Ramandeep Kaur,Renaud, Jean-Luc,Bruneau, Christian
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p. 1943 - 1952
(2007/10/03)
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- A Convenient and Effective Method for Synthesizing β-Amino-α ,β-Unsaturated Esters and Ketones
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A convenient and effective method for the preparation of β-amino-α, β-unsaturated esters and ketones has been developed through silica gel-catalyzed and solvent-free reactions of β-dicarbonylic compounds with ammonia and primary amines.
- Gao, Yuanhe,Zhang, Qihan,Xu, Jiaxi
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p. 909 - 916
(2007/10/03)
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- Zn(ClO4)2·6H2O as a Powerful Catalyst for the Conversion of β-Ketoesters into β-Enamino Esters
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Zn(ClO4)2·6H2O proved to be a very powerful catalyst for the condensation of primary and secondary amines with β-ketoesters to give N-substituted β-enaminoesters.
- Bartoli, Giuseppe,Bosco, Marcella,Locatelli, Manuela,Marcantoni, Enrico,Melchiorre, Paolo,Sambri, Letizia
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p. 239 - 242
(2007/10/03)
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- Polycyclic compounds
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PCT No. PCT/GB96/02945 Sec. 371 Date Aug. 25, 1998 Sec. 102(e) Date Aug. 25, 1998 PCT Filed Nov. 28, 1996 PCT Pub. No. WO97/19929 PCT Pub. Date Jun. 5, 1997Compounds of Formula (I), methods for their preparation, pharmaceutical formulations and use thereof.
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- Mechanism of hydrolysis and structure-stability relationship of enaminones as potential prodrugs of model primary amines
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The objective of this work was to investigate the chemistry and the structure-stability relationship of enaminones (a class of enamines formed between a primary amine and a 1,3-dicarbonyl compound) and to evaluate their potential usefulness as prodrugs of primary amines. The acid-catalyzed degradation of the enaminones was found to be very sensitive to minor differences in the structure of the 1,3-dicarbonyl compound used to form the enaminone, but relatively insensitive to changes in the amine portion of the enaminones. A correlation was found between the rate of enaminone hydrolysis and the pK(a) of the 1,3-dicarbonyl compound, suggesting that the rate-controlling step in the hydrolysis of the enaminones was the proton addition to the vinyl carbon of the enaminone. Enaminones formed with cyclic 1,3-dicarbonyl compounds were significantly more stable than those formed with structurally similar acyclic compounds. Based on chemical stability considerations alone, enaminones do not appear to be good candidates as prodrugs of primary amines. Evidence is presented, however, that enaminones formed between amines and 1,3-ketoesters or lactones may be subject to enzyme-catalyzed degradation. Further research on the design of enaminones destabilized by a triggering enzymatic event that results in the loss of conjugation (e.g., ester or lactone hydrolysis or an oxidation/reduction event) may prove worth pursuing.
- Naringrekar,Stella
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p. 138 - 146
(2007/10/02)
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