- Homarine Alkyl Ester Derivatives as Promising Acetylcholinesterase Inhibitors
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Reversible acetylcholinesterase (AChE) inhibitors are key therapeutic tools to modulate the cholinergic connectivity compromised in several degenerative pathologies. In this work, four alkyl esters of homarine were synthesized and screened by using Electrophorus electricus AChE and rat brain AChE-rich fraction. Results showed that all homarine alkyl esters are able to inhibit AChE by a competitive inhibition mode. The effectiveness of AChE inhibition increases with the alkyl side chain length of the homarine esters, being HO?C16 (IC50=7.57±3.32 μM and Ki=18.96±2.28 μM) the most potent inhibitor. The fluorescence quenching studies confirmed that HO?C16 is the compound with higher selectivity and affinity for the tryptophan residues in the catalytic active site of AChE. Preliminary cell viability studies showed that homarine esters display no toxicity for human neuronal SH-SY5Y cells. Thus, the long-chain homarine esters emerge as new anti-cholinesterase agents, with potential to be considered for therapeutic applications development.
- Jo?o, Karen G.,Videira, Romeu A.,Paiva-Martins, Fátima,Valent?o, Patrícia,Pereira, David M.,Andrade, Paula B.
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p. 3315 - 3325
(2021/08/30)
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- Preparation of Carbamates, Esters, Amides, and Unsymmetrical Ureas via Br?nsted Acid-Activated N-Acyl Imidazoliums
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We report the application of Br?nsted acid-activated N-acyl imidazoliums as versatile intermediates in carbonyl transformations. The efficient and scalable procedure was validated on a diverse set of carbamates, esters, amides, and unsymmetrical ureas (21 examples, up to 91% yield). Additionally, we exemplify this method on multikilogram scale for the synthesis of an electron-deficient carbamate.
- Watson, Rebecca B.,Butler, Todd W.,Deforest, Jacob C.
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supporting information
p. 500 - 506
(2021/01/09)
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- Practical: In situ -generation of phosphinite ligands for palladium-catalyzed carbonylation of (hetero)aryl bromides forming esters
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An effective method for alkoxycarbonylation of (hetero)aryl bromides is developed in the presence of in situ-generated phosphinite ligands tBu2POR (R = nBu, nPr, Et or Me). For this purpose commercially available tBu2PCl was used as the pre-ligand in the presence of different alcohols. For the first time cross coupling reactions with two alcohols-one generating the ligand, the other used as substrate-were developed. Through this method, ligand optimization can be performed in a more efficient manner and the desired products could be obtained with good yields and selectivity.
- Wang, Lin,Neumann, Helfried,Spannenberg, Anke,Beller, Matthias
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supporting information
p. 7469 - 7472
(2017/07/12)
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- Synthetic method of an ester compound
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The invention discloses a synthetic method of an ester compound and belongs to the technical field of organic synthesis. The synthetic method includes the steps of: dissolving an aldehyde compound (1) and a halogenated hydrocarbon compound (2) in a solvent, adding an oxidant and a catalyst, and performing a reaction at 60-100 DEG C to obtain the target product ester compound (3). A reaction equation of the synthetic method is represented as follows. The method, compared with the prior art, has the following advantages: 1) the raw materials are easy to obtain and are low in cost; 2) the reaction conditions are mild, operations are simple, and reaction time is short; and 3) a substrate has wide available range and can be used for synthesis of various ester compounds.
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Paragraph 0075; 0076; 0077
(2017/02/02)
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- Synthesis and structures of 1,2,4-triazoles derivatives
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Abstract A series of novel 1,2,4-triazole derivatives were synthesized, and their structures were characterized by IR, UV-Vis, FL, NMR, ESI-MS, and elemental analysis. In the meanwhile, the single crystal structures of 3,4-diethyl-5-(4-pyridyl)-1,2,4-triazole and 3,4-dimethyl-5-(o-hydroxyphenyl)-1,2,4-triazole were determined by X-ray diffraction.
- Wang, Ning,Sheng, Jun-Feng,Song, Fei,Tong, Yu-Zhu,Wang, Zuo-Xiang
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p. 746 - 751
(2015/05/05)
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- Iron pentacarbonyl in alkoxy- and aminocarbonylation of aromatic halides
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We have identified reaction conditions for a Heck-type carbonylation based on [Fe(CO)5]. Preliminary optimization of alkoxycarbonylation on 2-bromonaphthalene defined functioning composition of the reaction mixture which was then applied on a small set of (hetero)aromatic halides. Respective aminocarbonylation of these halides with different amines, including aniline and benzotriazole, was accomplished with reasonable results.
- Babjak, Matej,Caletková, O?ga,?uri?ová, Diana,Gracza, Tibor
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supporting information
p. 2579 - 2584
(2015/01/09)
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- Transesterification for synthesis of carboxylates using aldehydes as acyl donors via C-H and C-O bond activations
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A new type of transesterification between aryl, heteroaryl, alkyl N-heteroarene-2-carboxylates and various aldehydes by C-H and C-O bond activations has been developed for the synthesis of versatile carboxylates. A possible mechanism containing oxidative addition of acyl-O bond in parent ester and radical cleavage of sp2 C-H bond in aldehyde is proposed.
- Bao, Yong-Sheng,Chen, Chao-Yue,Huang, Zhi-Zhen
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p. 8344 - 8349,6
(2020/10/15)
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- Efficient carbonylation of aryl and heteroaryl bromides under atmospheric pressure of CO
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In the presence of Et and n-BuOH, efficient alkoxycarbonylation of (hetero)aromatic bromides was achieved under atmospheric pressure of carbon monoxide with in situ generated palladium/rac-BINAP as catalyst. Georg Thieme Verlag Stuttgart - New York.
- Yang, Weizhun,Han, Wei,Zhang, Weidong,Shan, Lei,Sun, Jiansong
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supporting information; experimental part
p. 2253 - 2255
(2011/10/19)
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- Copper-catalyzed synthesis of esters from ketones. Alkyl group as a leaving group
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The conversion of ketones to esters has been achieved through the use of Cu catalyst and tetrabutylammonium nitrite. This reaction involves the activation of the less activated C-C bond, and the alkyl group is removed as a leaving group. Various isopropyl ketones are found to be good substrates for this reaction.
- Nakatani, Yuji,Koizumi, Yuichiro,Yamasaki, Ryu,Saito, Shinichi
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supporting information; experimental part
p. 2067 - 2070
(2009/04/08)
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- New cyclopentadienyl, indenyl or fluorenyl substituted phosphine compounds and their use in catalytic reactions
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The invention is directed to a phosphine compound represented by general formula (1) wherein R' and R" independently are selected from alkyl, cycloalkyl and 2-furyl radicals, or R' and R" are joined together to form with the phosphorous atom a carbon-phosphorous monocycle comprising at least 3 carbon atoms or a carbon-phosphorous bicycle; the alkyl radicals, cycloalkyl radicals, and carbon-phosphorous monocycle being unsubstituted or substituted by at least one radical selected from the group of alkyl, cycloalkyl, aryl, alkoxy, and aryloxy radicals; Cps is a partially substituted or completely substituted cyclopentadien-1-yl group, including substitutions resulting in a fused ring system, and wherein a substitution at the 1-position of the cyclopentadien-1-yl group is mandatory when the cyclopentadien-1-yl group is not part of a fused ring system or is part of an indenyl group. Also claimed is the use of these phosphines as ligands in catalytic reactions and the preparation of these phosphines.
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Page/Page column 64; 65
(2008/06/13)
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- Efficient carbonylation of aryl and heteroaryl bromides using a palladium/diadamantylbutylphosphine catalyst
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A general palladium-catalyzed alkoxycarbonylation of aryl and heteroaryl bromides has been developed in the presence of bulky monodentate phosphines. Studies of the butoxycarbonylation of three model substrates revealed the advantages of di-1-adamantyl-n-butylphosphine compared to other ligands. In the presence of this catalyst system various bromoarenes provided the corresponding benzoic acid derivatives (ester, amides, acids) in excellent yield at low catalyst loadings (0.5 mol% Pd or below).
- Neumann, Helfried,Brennfuehrer, Anne,Gross, Peter,Riermeier, Thomas,Almena, Juan,Beller, Matthias
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p. 1255 - 1261
(2007/10/03)
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- Alumina sulfuric acid as a novel heterogeneous system for esterification of carboxylic acids in solvent free conditions
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Neat chlorosulfonic acid reacts with alumina to give alumina sulfuric acid (ASA) in which sulfuric acid is immobilised on the surface of alumina via a covalent bond. Carboxylic acids can be readily converted to their corresponding esters with a combination of ASA and alcohols in solvent free conditions.
- Sharghi, Hashem,Sarvari, Mona Hosseini,Eskandari, Razieh
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p. 488 - 491
(2007/10/03)
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- No stirring necessary: Parallel carbonylation of aryl halides with CO and various alcohols under pressure
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The parallel carbonylation of aryl halides with 6-25 bar of CO in 1-mL vials in a standard autoclave was investigated. 4-Bromoacetophenone and 2-chloropyridine were used as model substrates with 102 different O-nucleophiles (primary and secondary alcohols, phenols). No inertization during the loading was necessary. Fifty esters (43 new, yield up to 60%) were isolated and characterized. Ether, ester, ketone, and sometimes even olefin functions were usually tolerated. The new method is suitable for screening and small scale products synthesis.
- Blaser, Hans-Ulrich,Diggelmann, Martin,Meier, Hans,Naud, Frederic,Scheppach, Elke,Schnyder, Anita,Studer, Martin
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p. 3725 - 3728
(2007/10/03)
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- Efficient Palladium-Catalyzed Alkoxycarbonylation of N-Heteroaryl Chlorides - A Practical Synthesis of Building Blocks for Pharmaceuticals and Herbicides
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The alkoxycarbonylation of various N-heteroaryl chlorides was examined in detail. Studies of the butoxycarbonylation of 2- and 3-chloropyridine revealed the importance of selecting both the right phosphine ligand and ligand concentration in order to obtain efficient conversion and selectivity. Amongst the different ligands tested, 1,4-bis(diphenylphosphino)butane (dppb) and 1,1'-bis(diphenylphosphino)ferrocene (dppf) led to the most efficient palladium catalyst systems for the conversion of 2- and 4-chloropyridines and similar heteroaryl chlorides. The best catalytic systems for the alkoxycarbonylation of less activated substrates, such as 3-chloropyridines, were found to be those containing 1,4-bis(dicyclohexylphosphino)butane. Good to excellent yields of a number of N-heterocyclic carboxylic acid esters were realized by applying the appropriate ligand in the right concentration at low catalyst loadings (0.005-0.5 mol percent Pd). For the first time catalyst turnover numbers (TON) of up to 13,000 were obtained for the carbonylation of a (hetero)aryl chloride.
- Beller, Matthias,Maegerlein, Wolfganf,Indolese, Adriano F.,Fischer, Christine
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p. 1098 - 1109
(2007/10/03)
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- Advances in the carbonylation of aryl halides using palladium catalysts
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The palladium-catalyzed carbonylation of aryl halides is shown to be a versatile tool for the synthesis of various benzoic and heteroaromatic acid derivatives. Recent developments from our laboratories in this area are presented.
- Beller, Matthias,Indolese, Adriano F.
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p. 684 - 687
(2007/10/03)
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- Reactions of Heterocyclic Aromatic Acetals Over γ-Alumina, Aluminium Phosphate and Aluminium Sulphate
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Reactions of twelve heterocyclic aromatic acetals (1a-12a) over solid catalysts such as γ-alumina (AL), aluminium phosphate (AP) and aluminium sulphate (AS) have been studied.The reactions of acetals over AL and AP lead to the corresponding ethers, esters and aldehydes, while over AS the products formed are the corresponding esters and aldehydes.The anomalous behaviour of pyrrole-2-aldehyde acetal (10a) and pyridine-2-aldehyde acetal (12a) over catalysts is of particular interest.Probable mechanisms have been suggested for the reactions.
- Raja, S.,Xavier, N.,Arulraj, S. J.
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p. 916 - 919
(2007/10/02)
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- Solvolysis of Di-2-pyridylketone Methiodide
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Di-2-pyridylketone methiodide undergoes a facile nucleophilic substitution reaction with various alcohols followed by subsequent cleavage and elmination of pyridinium methiodide and the correspoing picolinates.
- Williams, R.L.,Neergaard, Sandra
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p. 1549 - 1550
(2007/10/02)
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