- Mechanosynthesis of N-methyl imines using recyclable imidazole-based acid-scavenger: In situ formed ionic liquid as catalyst and dehydrating agent
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1,1′-(1,4-Butanediyl)bis(imidazole) was prepared by a modified method and its application as an efficient promoter was demonstrated for the mechanosynthesis of N-methyl imines using ball milling as a non-conventional process under solvent-free conditions. In this new protocol design, the bis-imidazole acted as a recyclable acid-scavenging agent. This efficient approach to the N-methyl imines displays a combination of the synthetic virtues of a non-conventional condensation reaction with ecological benefits and convenience of a facile mechanosynthetic process. The current method has advantages such as reduced waste by avoiding solvent, exclusion of hazardous materials during the reaction, elimination of handling an anhydrous gas in an evacuated container or a solution of methylamine in ethanol, good yields for relatively unreactive benzaldehydes containing electron-donating substituents, short reaction times, and metal- and acid-free conditions. Furthermore, the promoter was easily regenerated and reused several times with no significant loss of activity.
- Khaligh, Nader Ghaffari,Ling, Ong Chiu,Mihankhah, Taraneh,Johan, Mohd Rafie,Ching, Juan Joon
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p. 194 - 199
(2018/12/04)
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- Facile synthesis of 4-substituted 1,2,4,5-tetrahydro-1,4-benzodiazepin-3-ones by reductive cyclization of 2-chloro-N-(2-nitrobenzyl)acetamides
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A facile and efficient method was developed for the synthesis of 1,2,4,5-tetrahydro-1,4-benzodiazepine-3-ones from 2-chloro-N-(2-nitrobenzyl)acetamides through a reductive cyclization using iron-ammonium chloride in ethanol–water in good yields. This method provides a simple approach to these benzodiazepine-3-ones which are of high value in the field of medicinal chemistry research.
- Sasiambarrena, Leandro D.,Barri, Ivan A.,Fraga, Guido G.,Bravo, Rodolfo D.,Ponzinibbio, Agustín
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supporting information
p. 264 - 267
(2019/01/04)
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- Synthesis of N-methyl imines in the presence of poly(N-vinylpyridine) as a reusable solid base catalyst by a mechanochemical process
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The synthesis of N-methyl imines was performed in the presence of catalytic amounts of poly(4-vinylpyridine) in high yields and rapidly at room temperature by a ball milling process. This new method has some advantages including good yields for relatively unreactive carbonyl compounds and short reaction times as well as being green in terms of avoiding the use of toxic reagents and solvents. The major advantage of this process is that the catalyst can be easily regenerated and reused several times without any significant loss of activity.
- Khaligh, Nader Ghaffari,Abbo, Hanna S.,Titinchi, Salam J. J.
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p. 901 - 910
(2017/02/10)
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- Quinazolinones, Quinazolinthiones, and Quinazolinimines as Nitric Oxide Synthase Inhibitors: Synthetic Study and Biological Evaluation
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The synthesis of different compounds with a quinazolinone, quinazolinthione, or quinazolinimine skeleton and their in vitro biological evaluation as inhibitors of inducible and neuronal nitric oxide synthase (iNOS and nNOS) isoforms are described. These d
- Camacho, M. Encarnación,Chayah, Mariem,García, M. Esther,Fernández-Sáez, Nerea,Arias, Fabio,Gallo, Miguel A.,Carrión, M. Dora
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p. 638 - 650
(2016/08/27)
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- Substituent-controlled annuloselectivity and stereoselectivity in the sulfa-Staudinger cycloadditions
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In the sulfa-Staudinger cycloadditions of imines and sulfonyl chlorides, the annuloselectivity is mainly controlled by the electronic effect of the α-substituents of sulfonyl chlorides and the nucleophilicity of imines. Sulfonyl chlorides with weakly elec
- Yang, Zhanhui,Chen, Ning,Xu, Jiaxi
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p. 3611 - 3620
(2015/04/22)
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- Simple and efficient one-pot solvent-free synthesis of N-methyl imines of aromatic aldehydes
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A one-pot solvent-free synthesis of N-methyl imines in good to excellent yields was performed by grinding together aromatic aldehydes and methylamine hydrochloride in the presence of a base. The best yields were achieved when an excess of methylamine hydrochloride and inexpensive sodium hydrogen carbonate was used (usually in a molar ratio ArCHO/CH3NH2· HCl/NaHCO3 = 1:5:5), allowing the reaction to proceed for 1 h (in the case of aromatic aldehydes containing electron-withdrawing substituents) or overnight (in the case of electron-rich aldehydes). After a simple work-up (extraction with diethyl ether) the obtained products were mostly pure enough for spectral characterization. In this way, 31 N-methyl imines were prepared, among which eight were synthesized for the first time. Their structures were elucidated by spectral means (1H- and 13C-NMR, IR, MS) whenever it was possible. In the case of salicylaldehyde and 4-chlorobenzaldehyde, the synthesis of the corresponding imines was also conducted on a gram-scale with a 72% and 84% isolated yield, respectively. The present approach not only provides good to high yields, but also eliminates the disadvantages of the traditional synthesis of N-methyl imines, such as the use of hazardous solvents and more or less expensive catalysts and the necessity of work/handling with an anhydrous gas in pressurized containers.
- Radulovi?, Niko S.,Miltojevi?, Ana B.,Vuki?evi?, Rastko D.
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p. 257 - 270
(2013/05/09)
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- Cholinesterase inhibitors: SAR and enzyme inhibitory activity of 3-[ω-(benzylmethylamino)alkoxy]xanthen-9-ones
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In this work, we further investigated a previously introduced class of cholinesterase inhibitors. The removal of the carbamic function from the lead compound xanthostigmine led to a reversible cholinesterase inhibitors 3. Some new 3-[ω-(benzylmethylamino)alkoxy]xanthen-9-one analogs were designed, synthesized, and evaluated for their inhibitory activity against both acetylcholinesterase (AChE) and butyrylcholinesterase (BuChE). The length of the alkoxy chain of compound 3 was increased and different substituents were introduced. From the IC50 values, it clearly appears that the carbamic residue is crucial to obtain highly potent AChE inhibitors. On the other hand, peculiarity of these compounds is the high selectivity toward BuChE with respect to AChE, being compound 12 the most selective one (6000-fold). The development of selective BuChE inhibitors may be of great interest to clarify the physiological role of this enzyme and to provide novel therapeutics for various diseases.
- Piazzi, Lorna,Belluti, Federica,Bisi, Alessandra,Gobbi, Silvia,Rizzo, Stefano,Bartolini, Manuela,Andrisano, Vincenza,Recanatini, Maurizio,Rampa, Angela
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p. 575 - 585
(2008/03/12)
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- Highly stereoselective Friedel-Crafts type cyclization. Facile access to enantiopure 1,4-dihydro-4-phenyl isoquinolinones
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The present report describes a stereoselective synthesis of 1,4-dihydro-4-phenyl isoquinolinones 5 based on a stereoselective Friedel-Crafts type cyclization. Cyclization precursors 1 were prepared in two steps, from the readily available (S)-mandelic acid, in 60-80% overall yield. The stereoselective electrophilic cyclization was accomplished in 20-86% yield and with 20-97% ee. In the course of this work, the presence of the amide carbonyl was found to be particularly important to guarantee a stereospecific process during the electrophilic aromatic substitution.
- Philippe, Nicolas,Denivet, Fran?ois,Vasse, Jean-Luc,Sopkova-De Olivera Santos, Jana,Levacher, Vincent,Dupas, Georges
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p. 8049 - 8056
(2007/10/03)
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- The development of a manufacturing route for the GPIIb/IIIa receptor antagonist SB-214857-A. Part 1: Synthesis of the key intermediate 2,3,4,5-tetrahydro-4-methyl-3-oxo-1H-1,4-benzodiazepine-2-acetic acid methyl ester, SB-235349
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The development of an efficient manufacturing route to 2,3,4,5-tetrahydro-4-methyl-3-Oxo-1H-1,4-benzodiazepine-2-acetic acid methyl ester SB-235349, a key intermediate in the synthesis of lotrafiban is described. The synthesis starts with 2-nitrobenzyl alcohol which is mesylated, reacted with methylamine and then dimethylacetylene dicarboxylate followed by reduction of the nitro group. Treatment of the resultant aniline with acid gives an intermediate quinazoline which rearranges on treatment with base to give a 1,4-benzodiazapine. Reduction of the exocyclic double bond affords SB-235349. The process can be run without isolation of any of the intermediates and has been used to prepare several tons of SB-235349.
- Andrews, Ian P.,Atkins, Richard J.,Breen, Gary F.,Carey, John S.,Forth, Michael A.,Morgan, David O.,Shamji, Amin,Share, Andrew C.,Smith, Stephen A. C.,Walsgrove, Timothy C.,Wells, Andrew S.
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p. 655 - 662
(2013/09/05)
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- POTENTIAL CNS ACTIVE 1-ARYL-2-AMINO-1-ETHANOL DERIVATIVES
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New N-(picolyl)-2-(methylamino)-1-aryl-1-ethanols (I) and their O-acyl derivatives (II) were synthesized.Their dopaminomimetic and antidepressant biological activities were examined and compared with the activities of N-(2-aminobenzyl)-2-(methylamino)-1-aryl-1-ethanols (III).It was established that in the reaction of N- methylamine (2) and styryl oxide, the two directions of the splitting of the epoxide ring give rise to two different products that were isolated and identified in the form of their O-acetyl derivatives (13 and 15, respectively).
- Zara-Kaczian, Erzsebet,Deak, Gyula,Gyoergy, Lajos
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p. 441 - 454
(2007/10/02)
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