- Microwave-Assisted Ruthenium-Catalysed ortho-C?H Functionalization of N-Benzoyl α-Amino Ester Derivatives
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A microwave-assisted highly efficient intermolecular C?H functionalization sequence has been developed to access substituted isoquinolones using α-amino acid esters as a directing group. This methodology enables a wide range of N-benzoyl α-amino ester derivatives to react via a Ru-catalysed C?H bond activation sequence, to form isoquinolones with moderate to excellent yields. As an additional advantage, our strategy proved to be widely applicable and also enabled the reaction of alkenes to provide access to alkenylated benzamides. The methodology was also extended towards the synthesis of isoquinoline alkaloids derivatives viz. oxyavicine and a dipeptide. The developed protocol is simple and cheap, avoids tedious workup procedures and works efficiently under MW irradiation. (Figure presented.).
- Sharma, Nandini,Bahadur, Vijay,Sharma, Upendra K.,Saha, Debasmita,Li, Zhenghua,Kumar, Yogesh,Colaers, Jona,Singh, Brajendra K,Van der Eycken, Erik V.
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supporting information
p. 3083 - 3089
(2018/08/24)
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- Highly efficient and recyclable copper based ionic liquid catalysts for amide synthesis
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A series of Cu based ionic liquids was synthesized by the reaction of 1-butyl-3-methylimidazolium salts and copper(ii) salts. These ionic liquids were investigated as catalysts in the synthesis of amides (primary, secondary and tertiary amides). For easy separation and recycling, the Cu based ionic liquids were decorated on nanocrystalline silicalite. The materials were characterized using powder X-ray diffraction, nitrogen adsorption, scanning and transmission electron microscopy, thermogravimetric analysis, and nuclear magnetic resonance, Fourier transform infrared and UV-visible spectroscopy. The Cu based ionic liquids decorated on nanocrystalline silicalite were found to be efficient and recyclable catalysts for the amide synthesis. The catalysts were found to be stable and show negligible loss of the activity even after five cycles.
- Rani, Poonam,Srivastava, Rajendra
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p. 7162 - 7170
(2016/08/09)
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- The α-effect in hydrazinolysis of 4-chloro-2-nitrophenyl x-substituted-benzoates: Effect of substituent x on reaction mechanism and the α-effect
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Second-order rate constants (kN) have been measured spectrophotometrically for the reaction of 4-chloro-2- nitrophenyl X-substituted-benzoates (6a-6h) with a series of primary amines including hydrazine in 80 mol % H2O/20 mol % DMSO at 25.0°C. The Bronsted-type plot for the reaction of 4-chloro-2-nitrophenyl benzoate (6d) is linear with βnuc = 0.74 when hydrazine is excluded from the correlation. Such a linear Bronsted-type plot is typical for reactions reported previously to proceed through a stepwise mechanism in which expulsion of the leaving group occurs in the rate-determining step (RDS). The Hammett plots for the reactions of 6a-6h with hydrazine and glycylglycine are nonlinear. In contrast, the Yukawa-Tsuno plots exhibit excellent linear correlations with ?X = 1.29-1.45 and r = 0.53-0.56, indicating that the nonlinear Hammett plots are not due to a change in RDS but are caused by resonance stabilization of the substrates possessing an electron-donating group (EDG). Hydrazine is ca. 47-93 times more reactive than similarly basic glycylglycine toward 6a-6h (e.g., the α-effect). The α-effect increases as the substituent X in the benzoyl moiety becomes a stronger electronwithdrawing group (EWG), indicating that destabilization of the ground state (GS) of hydrazine through the repulsion between the nonbonding electron pairs on the two N atoms is not solely responsible for the substituent-dependent α-effect. Stabilization of transition state (TS) through five-membered cyclic TSs, which would increase the electrophilicity of the reaction center or the nucleofugality of the leaving group, contributes to the α-effect observed in this study.
- Kim, Min-Young,Kim, Tae-Eun,Lee, Jieun,Um, Ik-Hwan
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p. 2271 - 2276
(2014/09/29)
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- Three-component metal-free arylation of isocyanides
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Mumm's the word: The title reaction can be performed by the addition of isocyanides to benzenediazonium salts in the presence of sodium or potassium carboxylates. The reaction involves nitrilium intermediates which may be trapped by water or carboxylic ac
- Basavanag, Unnamatla M. V.,Dos Santos, Aurelie,El Kaim, Laurent,Gamez-Montano, Rocio,Grimaud, Laurence
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supporting information
p. 7194 - 7197
(2013/07/26)
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- Highly efficient oxidative amidation of aldehydes with amine hydrochloride salts
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A mild and efficient copper-catalyzed oxidative amidation of aldehydes was developed using amine HCl salts and tert-butyl hydroperoxide as an oxidant. Copyright
- Yoo, Woo-Jin,Li, Chao-Jun
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p. 13064 - 13065
(2008/02/08)
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- An efficient one-pot synthesis of hippuric acid ethyl ester derivatives
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A rapid, one-pot procedure is described for the preparation of the ethyl esters of a number of ring-substituted N-benzoyl glycine (hippuric acid) derivatives from readily-available starling materials.
- Conway, Samuel C.,Perni, Robert B.
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p. 1539 - 1545
(2007/10/03)
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- An unusual ground-state stabilization effect and origins of the α- effect in aminolyses of Y-substituted phenyl X-substituted benzoates
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Second-order rate constants have been measured spectrophotometrically for the reactions of X-C6H4CO2C6H4-Y with a series of primary amines in H2O containing 20 mol% DMSO at 25.0 ± 0.1°C. The reactivity increases as the substituent (X and Y) becomes a stronger electron-withdrawing group. The σ+ constants give better Hammett correlation than σ constants for the reactions of 4-nitrophenyl X-substituted benzoates with glycylglycine (glygly) and hydrazine (NH2NH2), indicating that the ground-state stabilization effect is unusually significant on the reaction rates. The reactions of X-C6H4CO2C6H4-Y with glygly and NH2NH2 appear to proceed through the same mechanism, but the degree of leaving-group departure and the negative charge developed in the acyl moiety at the rate-determining TS is considered to be more significant for the glygly system than the NH2NH2 system based on β(1g) and ρ(x) values. The magnitude of the α-effect is observed to be not always dependent on the β(nuc) value but dependent on the electronic nature of the substituent X and Y, i.e., an electron-donating substituent increases the α-effect, while an electron-withdrawing one decreases the α-effect. The present study has led to the conclusion that the ground-state effect is important for the reaction rates but it is not solely responsible for the α-effect, and the intramolecular H-bonding interactions (4) are proposed for the cause of the increasing or decreasing α-effect trends observed in the present system.
- Um, Ik-Hwan,Chung, Eun-Kyung,Lee, So-Mi
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p. 729 - 737
(2007/10/03)
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- Synthesis, structure, and acylating properties of 1-aroyloxy-4,5-dimethyl- 1,2,3-triazoles
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Lead tetra-acetate oxidation of α-hydroxyimino aroylhydrazones of biacetyl (1) gives 1-aroyloxy-4,5-dimethyl-1,2,3-triazoles (2), the structures of which were confirmed by X-ray analysis. A mechanism for this reaction is discussed. The products (2) are effective aroylating agents for the amino function under mild conditions.
- Theocharis,Maroulis,Hadjiantoniou-Maroulis,Alexandrou
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p. 619 - 621
(2007/10/02)
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- UNUSUAL N-ACYLATION OF GLYCINE SCHIFF BASES. A SIMPLE APPROACH TO 3,3-DIPHENYLAZIRIDINE-2-CARBOXYLATES
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Treatment of azaallyl anions, generated from glycine Schiff bases, with Ar-acyl halides furnishes N-acylaziridines via intramolecular cyclization.
- Rao, M. Narayana,Holkar, A. G.,Ayyangar, N. R.
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p. 4717 - 4720
(2007/10/02)
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