- Heterocyclic Deformations from Molecular Enlargement
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The ease of distortion of saturated nitrogen heterocycles has been examined by progressively increasing the bulk of the substituent at nitrogen.The heterocycles included the pharmacophoric piperidine and morpholine six-membered rings, as well as the five-membered oxazolidine ring.Response to increased bulk of substitution was intended to be a crude model for distortions within the drug-receptor complex.Substitution at nitrogen included methyl, (1-adamantyl)methyl, and 6-substituted β-cyclodextrin within a tetrahedral series, and acetyl and (1-adamantyl)carbonyl within a trigonal series.With methyl and acetyl serving as standards for the undistorted rings, we have found that the NCH2CH2X dihedral angle within all three heterocycles is decreased anly by about 1 deg on introduction of adamantyl groups.In agreement with this flattening distortion, the barrier to ring reversal of the piperidine is decreased by 1.4 kcal/mol on replacement of N-methyl by N-adamantylmethyl.The β-cyclodextrin ring imposes a much more severe distortion, as this same dihedral angle in the piperidine and morpholine rings decreases 5-6 deg.The barrier to rotation about the amide bond decreases 5-6 kcal/mol in all three heterocycles on going from acetyl to adamantylcarbonyl.These studies show that the response of these heterocycles to incresed steric bulk of N substitution is a flatter and hence more flexible ring.
- Lambert, Joseph B.,Wharry, Stephen M.
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Read Online
- Synthesis of 4-Vinylmorpholine Based on Acetylene
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It has been shown that from the possible methods for the synthesis of 4-vinylmorpholine, the vinylation of morpholine with acetylene remains acceptable. A technologically accessible method for vinylation of morpholine with acetylene at atmospheric pressure was developed.
- Asratyan,Bagdasaryan,Markosyan, A. Dzh.,Badalyan,Attaryan
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Read Online
- Electrophilic Sulfonium-Promoted Peptide and Protein Amidation in Aqueous Media
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A novel amidation strategy using electrophilic sulfonium, which is soluble and stable in aqueous conditions, was developed. The sulfoniums could activate thioacid and carboxyl acid to efficiently react with amines to afford amides. This method enables applications in amidation in both aqueous media and solid-phase peptide synthesis, peptide/protein modifications, and reactive lysines of a proteome at pH 10 with activity-based protein profiling. A peptide ligand-directed labeling of the USP7-UBL2 domain was also performed using this method.
- Wan, Chuan,Feng, Yuan,Hou, Zhanfeng,Lian, Chenshan,Zhang, Liang,An, Yuhao,Sun, Jinming,Yang, Dongyan,Jiang, Chenran,Yin, Feng,Wang, Rui,Li, Zigang
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supporting information
p. 581 - 586
(2022/01/20)
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- A CO2-Catalyzed Transamidation Reaction
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Transamidation reactions are often mediated by reactive substrates in the presence of overstoichiometric activating reagents and/or transition metal catalysts. Here we report the use of CO2as a traceless catalyst: in the presence of catalytic amounts of CO2, transamidation reactions were accelerated with primary, secondary, and tertiary amide donors. Various amine nucleophiles including amino acid derivatives were tolerated, showcasing the utility of transamidation in peptide modification and polymer degradation (e.g., Nylon-6,6). In particular,N,O-dimethylhydroxyl amides (Weinreb amides) displayed a distinct reactivity in the CO2-catalyzed transamidation versus a N2atmosphere. Comparative Hammett studies and kinetic analysis were conducted to elucidate the catalytic activation mechanism of molecular CO2, which was supported by DFT calculations. We attributed the positive effect of CO2in the transamidation reaction to the stabilization of tetrahedral intermediates by covalent binding to the electrophilic CO2
- Yang, Yang,Liu, Jian,Kamounah, Fadhil S.,Ciancaleoni, Gianluca,Lee, Ji-Woong
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p. 16867 - 16881
(2021/11/18)
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- N-acetylation of amines in continuous-flow with acetonitrile—no need for hazardous and toxic carboxylic acid derivatives
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A continuous-flow acetylation reaction was developed, applying cheap and safe reagent, acetonitrile as acetylation agent and alumina as catalyst. The method developed utilizes milder reagent than those used conventionally. The reaction was tested on various aromatic and aliphatic amines with good conversion. The catalyst showed excellent reusability and a scale-up was also carried out. Furthermore, a drug substance (paracetamol) was also synthesized with good conversion and yield.
- Fül?p, Ferenc,Mándity, István M.,Orsy, Gy?rgy
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- IrIII-Catalyzed direct syntheses of amides and esters using nitriles as acid equivalents: A photochemical pathway
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An unprecedented IrIII[df(CF3)ppy]2(dtbbpy)PF6-catalyzed simple photochemical process for direct addition of amines and alcohols to the relatively less reactive nitrile triple bond is described herein. Various amides and esters are synthesized as the reaction products, with nitriles being the acid equivalents. A mini-library of different types of amides and esters is made using this mild and efficient process, which uses only 1 mol% of photocatalyst under visible light irradiation (λ = 445 nm). The reaction strategy is also efficient for gram-scale synthesis.
- Talukdar, Ranadeep
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supporting information
p. 5303 - 5308
(2020/04/17)
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- Direct amide formation in a continuous-flow system mediated by carbon disulfide
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Amide bonds are ubiquitous in nature. They can be found in proteins, peptides, alkaloids, etc. and they are used in various synthetic drugs too. Amide bonds are mainly made by the use of (i) hazardous carboxylic acid derivatives or (ii) expensive coupling agents. Both ways make the synthetic technology less atom economic. We report a direct flow-based synthesis of amides. The developed approach is prominently simple and various aliphatic and aromatic amides were synthetized with excellent yields. The reaction in itself is carried out in acetonitrile, which is considered as a less problematic dipolar aprotic solvent. The used coupling agent, carbon disulfide, is widely available and has a low price. The utilized heterogeneous Lewis acid, alumina, is a sustainable material and it can be utilized multiple times. The technology is considerably robust and shows excellent reusability and easy scale-up is carried out without the need of any intensive purification protocols.
- Orsy, Gy?rgy,Fül?p, Ferenc,Mándity, István M.
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p. 7814 - 7818
(2020/12/28)
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- Environmentally benign decarboxylative: N-, O-, and S-Acetylations and acylations
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An operationally simple and general method for acetylation and acylation of a wide variety of substrates (amines, alcohols, phenols, thiols, and hydrazones) has been reported. Meldrum's acid and its derivatives have been used as an air-stable, non-volatile, cost-effective, and easy to handle acetylating/acylating agent. Easily separable byproducts (CO2 and acetone) allowed the isolation of analytically pure acetylated products without the requirement of work-up and any chromatography. This journal is
- Ghosh, Santanu,Purkait, Anisha,Jana, Chandan K.
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supporting information
p. 8721 - 8727
(2020/12/30)
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- Phenysilane and Silicon Tetraacetate: Versatile Promotors for Amide Synthesis
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Phenylsilane was reevaluated as a useful coupling reagent for amide synthesis. At room temperature, a wide range of amides and peptides were obtained in good to excellent yields (up to 99 %). For the first time, Weinreb amides synthesis mediated by a hydrosilane were also documented. Comparative experiments with various acetoxysilanes suggested the involvement of a phenyl-triacyloxysilane. From this mechanistic study, silicon tetraacetate was shown as an efficient amine acylating agent.
- Morisset, Eléonore,Chardon, Aurélien,Rouden, Jacques,Blanchet, Jér?me
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supporting information
p. 388 - 392
(2020/01/24)
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- Preparation method for N-acetylmorpholine
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The invention provides a preparation method for N-acetylmorpholine. The method comprises the following steps: performing a reaction on morpholine and ethyl acetate in a reactor, wherein the reaction temperature is 140-160 DEG C, the reaction time is 6-10 h, and the reaction pressure is normal pressure; and at the same time, performing a synthetic reaction under the condition of an ionic liquid catalyst to obtain crude N-acetylmorpholine, performing dealcoholization treatment on the crude N-acetylmorpholine, performing dehydration treatment, separating the morpholine, and performing rectification to obtain the N-acetylmorpholine fine product. The process provided by the invention is efficient, economical, harmless, safe, environmentally friendly, energy-saving and emission-reducing, and prepares the high-purity N-acetylmorpholine product.
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Paragraph 0041-0059
(2020/01/12)
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- Carbonylation of C?N Bonds in Tertiary Amines Catalyzed by Low-Valent Iron Catalysts
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The first iron catalysts able to promote the formal insertion of CO into the C?N bond of amines are reported. Using low-valent iron complexes, including K2[Fe(CO)4], amides are formed from aromatic and aliphatic amines, in the presence of an iodoalkane promoter. Inorganic Lewis acids, such as AlCl3 and Nd(OTf)3, have a positive influence on the catalytic activity of the iron salts, enabling the carbonylation at a low pressure of CO (6 to 8 bars).
- Nasr Allah, Tawfiq,Savourey, Solène,Berthet, Jean-Claude,Nicolas, Emmanuel,Cantat, Thibault
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supporting information
p. 10884 - 10887
(2019/07/15)
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- Synthesis of diverse libraries of carboxamides via chemoselective N-acylation of amines by carboxylic acids employing Br?nsted acidic IL [BMIM(SO3H)][OTf]
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Chemoselective N-acylation of amines with carboxylic acids as acyl electrophiles and Br?nsted acidic IL [BMIM(SO3H)][OTf] as promoter is reported under both thermal and microwave irradiation to produce libraries of carboxamides in good to excellent yields after a simple workup. The protocol is compatible with structurally diverse 1° and 2° amines and works in the presence of sensitive functional groups such as thiols and phenols. The potential for recycling and reuse of the IL is also demonstrated.
- Savanur, Hemantkumar M.,Malunavar, Shruti S.,Prabhala, Pavankumar,Sutar, Suraj M.,Kalkhambkar, Rajesh G.,Laali, Kenneth K.
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supporting information
(2019/09/30)
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- Manganese-mediated acetylation of alcohols, phenols, thiols, and amines utilizing acetic anhydride
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Manganese(II) chloride-catalyzed acetylation of alcohols, phenols thiols and amines with acetic anhydride is reported. This method is environment-friendly and economically viable as it involves inexpensive, relatively benign catalyst, mild reaction condition, and simple workup. Acetylation is performed under the solvent-free condition at ambient temperature and acetylated products obtained in good to excellent yields. Primary, secondary heterocyclic amines, and phenols with various functional groups are smoothly acetylated in good yields. This method exhibits exquisite chemoselectivity, the amino group is preferentially acetylated in the presence of a hydroxyl/thiol group.
- Jain, Isha,Sharma, Ramandeep,Malik, Payal
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supporting information
p. 2952 - 2960
(2019/09/13)
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- Electrochemical anion pool synthesis of amides with concurrent benzyl ester synthesis
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An electrosynthesis method for amide bond formation has been developed in an attempt to increase the atom economy for this class of reactions. This "anion pool" method electrochemically generates strong nucleophiles from amine substrates. The amine nucleophiles then react with acid anhydrides to generate amides, and the by-product from this reaction undergoes further chemical transformations to generate pharmaceutically relevant benzoic esters. These one-pot reactions are operationally simple, are performed at room temperature, and avoid rare transition metals and added bases. The amide synthesis is amenable to primary and secondary amines and a variety of anhydrides with yields up to 90% obtained. Atom economy and process mass index (PMI) values calculated for this procedure indicate that this process can be considered greener compared to traditional amide synthesis routes used by industry. Furthermore, this electrochemical approach showed unique selectivity when substrates that contained two inequivalent amine moieties were examined.
- Mevan Dissanayake,Melville, Alex D.,Vannucci, Aaron K.
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supporting information
p. 3165 - 3171
(2019/06/18)
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- Synthesis of acetamides using CO2, methanol, H2 and amines
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Herein, we report the synthesis of acetamides from CO2, methanol, H2 and corresponding amines, which is a new route used to synthesize acetamides. It was found that the Rh catalyst with LiI/LiCl as promoters could effectively catalyze this reaction. Interestingly, no ligand was required and amine substrates played a role in accelerating the reaction.
- Zhang, Jingjing,Qian, Qingli,Wang, Ying,Asare Bediako, Bernard Baffour,Cui, Meng,Yang, Guanying,Han, Buxing
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supporting information
p. 233 - 237
(2019/01/28)
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- Dimethomorph production method
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The invention discloses a dimethomorph production method in the technical field of pesticide production. The production method comprises: 1) synthesizing veratrole; 2) synthesizing 3,4-dimethoxy-4-chloro-benzophenone; 3) synthesizing acetylmorpholine; and 4) synthesizing dimethomorph. Sodium tert-butoxide is taken as a basic catalyst for synthesizing dimethomorph from 3,4-dimethoxy-4-chloro-benzophenone and acetylmorpholine, and a sodium hydroxide solution is used to perform alkali washing on a reactant in a reaction vessel. Sodium hydroxide has a catalytic effect on synthesis of dimethomorphfrom 3,4-dimethoxy-4-chloro-benzophenone and acetylmorpholine. The defect that the catalytic effect of sodium tert-butoxide is gradually reduced due to unstable chemical property of sodium tert-butoxide and degradation of sodium tert-butoxide when sodium tert-butoxide comes into water is overcome. The dimethomorph product is improved in conversion rate and purity.
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Paragraph 0011; 0012; 0013
(2018/06/15)
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- Direct Observation of Acyl Nitroso Compounds in Aqueous Solution and the Kinetics of Their Reactions with Amines, Thiols, and Hydroxamic Acids
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Acyl nitroso compounds or nitrosocarhonyls (RC(O)N=O) are reactive short-lived electrophiles, and their hydrolysis and reactions with nucleophiles produce HNO. Previously, direct detection of acyl nitroso species in nonaqueous media has been provided by time-resolved infrared spectroscopy demonstrating that its half-life is about 1 ms. In the present study hydroxamic acids (RC(O)NHOH) are oxidized electrochemically in buffered aqueous solutions (pH 5.9-10.2) yielding transient species characterized by their maximal absorption at 314-330 nm. These transient species decompose via a first-order reaction yielding mainly HNO and the respective carboxylic acid and therefore are ascribed to RC(O)N=O. The sufficiently long half-life of RC(O)N=O in aqueous solution allows for the first time the study of the kinetics of its reactions with various nucleophiles demonstrating that the nucleophilic reactivity follows the order thiolate > hydroxamate > amine. Metal chelates of CH3C(O)NHOH catalyze the hydrolysis of CH3C(O)N=O at the efficacy order of CuII > ZnII > NiII > CoII where only CuII catalyzes the hydrolysis also in the absence of the hydroxamate. Finally, oxidation of hydroxamic acids generates HNO, and the rate of this process is determined by the half-life of the respective acyl nitroso compound.
- Maimon, Eric,Lerner, Ana,Samuni, Amram,Goldstein, Sara
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p. 7006 - 7013
(2018/09/06)
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- Manganese-Catalyzed Direct Conversion of Ester to Amide with Liberation of H2
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A simple and efficient Mn-catalyzed acylation of amines is achieved using both acyl and alkoxy functions of unactivated esters with the liberation of molecular hydrogen as a sole byproduct. The present protocol provides an atom-economical and sustainable route for the synthesis of amides from esters by employing an earth-abundant manganese salt and inexpensive phosphine-free tridentate ligand.
- Mondal, Akash,Subaramanian, Murugan,Nandakumar, Avanashiappan,Balaraman, Ekambaram
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supporting information
p. 3381 - 3384
(2018/06/11)
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- Interception of amide ylides with sulfonamides: Synthesis of (: E)- N -sulfonyl amidines catalyzed by Zn(OTf)2
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Through the interception of amide ylides with sulfonamides, we herein report the first general example of an intermolecular condensation reaction between sulfonamides and amides. Beyond formamides, this approach was successfully applied to a variety of lactams and linear amides, giving rise to a broad array of (E)-N-sulfonyl amidines.
- Chen, Jijun,Long, Wenhao,Fang, Shangwen,Yang, Yonggang,Wan, Xiaobing
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supporting information
p. 13256 - 13259
(2017/12/26)
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- Diphenylsilane as a coupling reagent for amide bond formation
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A simple procedure for amide bond formation using diphenylsilane as a coupling reagent is described. This methodology enables the direct coupling of carboxylic acids with primary and secondary amines, releasing only hydrogen and a siloxane as by-products. Only one equivalent of each partner is needed, providing a more sustainable amidation method producing minimal wastes. This methodology was also extended to the synthesis of peptides and lactams by addition of Hünig's base (DIPEA) and 4-dimethylaminopyridine (DMAP).
- Sayes, Morgane,Charette, André B.
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supporting information
p. 5060 - 5064
(2017/11/09)
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- Cu(II)-Mediated keto C(sp3)-H bond α-acyloxylation of N, N-dialkylamides with aromatic carboxylic acids
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The selective oxidative coupling of aromatic carboxylic acids with the C(sp3)-H bond adjacent to the keto group of alkylamides has been developed by employing a low cost copper source. This provides an efficient approach for synthesis of O-benzoylglycolamides. The protocol displayed good functional group tolerance. A broad range of benzoic acids directly coupled with alkylamides to afford a variety of O-benzoylglycolamides in moderate to good yields. In addition, a reasonable radical mechanism was proposed based on EPR experiments.
- Li, Wenjing,Yin, Changzhen,Yang, Xiao,Liu, Hailong,Zheng, Xueli,Yuan, Maolin,Li, Ruixiang,Fu, Haiyan,Chen, Hua
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supporting information
p. 7594 - 7599
(2017/09/27)
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- Preparation method of acrylamide-based compounds
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The present invention relates to the field of fine chemical materials, particularly to a new mild, efficient and economical preparation process technology of a class of acrylamide-type compounds, wherein a beta-amine substituted propionamide precursor is subjected to an in-situ amine elimination reaction under the action of a suitable electrophilic reagent so as to prepare the target product.
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Paragraph 0013; 0014; 0015; 0025
(2018/01/11)
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- Iron-Catalyzed Amide Formation from the Dehydrogenative Coupling of Alcohols and Secondary Amines
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The five-coordinate iron(II) hydride complex (iPrPNP)Fe(H)(CO) (iPrPNP = N[CH2CH2(PiPr2)]2) selectively catalyzes the dehydrogenative intermolecular coupling of alcohols and secondary amines to form tertiary amides. This is the most productive base-metal catalyst for dehydrogenative amidation reported to date, in some cases achieving up to 600 turnovers. The catalyst works well for sterically undemanding amines and alcohols or cyclic substrates and is particularly effective in the synthesis of formamides from methanol. However, the catalyst performance declines rapidly with the incorporation of large substituents on the amine or alcohol substrate. Variable-temperature NMR spectroscopic studies suggest that the catalyst resting state is an off-cycle iron(II) methoxide species, (iPrPN(H)P)Fe(H)(OCH3)(CO), resulting from addition of methanol across the Fe-N bond of (iPrPNP)Fe(H)(CO). This reversibly formed iron(II) methoxide complex is favored at mild temperatures but eliminates methanol upon heating.
- Lane, Elizabeth M.,Uttley, Katherine B.,Hazari, Nilay,Bernskoetter, Wesley
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p. 2020 - 2025
(2017/06/13)
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- Doping of copper (I) oxide onto a solid support as a recyclable catalyst for acetylation of amines/alcohols/phenols and synthesis of trisubstituted imidazole
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A study of copper-mediated C-heteroatom especially C-N and C-O bond formations using simpler methodologies has been carried out. In the present work, acetylation of various substrates such as amines, phenols and alcohols; synthesis of 2,4,5-trisubstituted imidazole is done using simple and easily available starting materials. Copper (I) oxide was synthesized in situ by the reduction of Fehling's solution with glucose followed by its anchoring onto different supports like silica, HAP, basic alumina and cellulose. Comparison and contrasts between the reactivity of copper (I) oxide supported onto different supports for these reactions are made. The reactivity of copper (I) oxide seems to be largely dependent on the nature of support and the most active catalyst for a particular reaction was further characterized by different spectroscopic techniques such as FTIR, XRD, TGA, XPS, SEM, TEM and AAS. The catalysts were found to be stable, easily recyclable without any significant loss in activity. Graphical abstract: Applications of solid supported copper (I) oxides (where solid support is silica, HAP, cellulose and basic alumina) are studied for various organic transformations with special emphasis on C-N and C-O bond formation reactions.[Figure not available: see fulltext.]
- Gupta, Manjulla,Gupta, Monika
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p. 231 - 241
(2016/01/09)
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- Reaction Mechanism in Ionic Liquids: Kinetics and Mechanism of the Aminolysis of 4-Nitrophenyl Acetate
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In this work, we report a kinetic study of the reactions of the title compound with secondary alicyclic amines at different temperatures in acetonitrile and several ionic liquids (ILs). From this study, we have described that the reactions in MeCN and in
- Pavez, Paulina,Millán, Daniela,Rojas, Mabel,Morales, Javiera I.,Santos, José G.
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p. 337 - 343
(2016/05/02)
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- An eco-friendly and highly efficient route for N-acylation under catalyst-free conditions
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An eco-friendly, simple, mild, chemoselective and highly efficient procedure for the acylation of primary and secondary amine function in various structurally and electronically aliphatic and aromatic compounds affording their corresponding N-Ac derivatives is developed. Mild conditions, simplicity and easier work-up are the main advantages of this method.
- Ouarna, Souad,K'tir, Hacène,Lakrout, Salah,Ghorab, Hamida,Amira, A?cha,Aouf, Zineb,Berredjem, Malika,Aouf, Nour-Eddine
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p. 913 - 919
(2015/10/28)
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- Preparation of conformationally restricted β2,2- and β2,2,3-amino esters and derivatives containing an all-carbon quaternary center
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β-Amino acids are routinely incorporated into peptidic drugs to increase their stability and to incur conformational biases. However, the synthesis of highly substituted β-amino acids still represents a great challenge. A new approach to their preparation is reported involving a Vilsmeier-Haack reaction with nonaromatic carbon nucleophiles. The highly challenging preparation of contiguous tertiary and all-carbon quaternary centers was successfully used to generate several β2,2,3-amino esters, such as derivatives of homoproline, homoalanine, and homopipecolinic esters.
- Romanens, Alexandre,Blanger, Guillaume
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supporting information
p. 322 - 325
(2015/01/30)
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- Direct Preparation of Amides from Amine Hydrochloride Salts and Orthoesters: A Synthetic and Mechanistic Perspective
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The conversion of a wide range of primary and secondary aliphatic and a few arylamine hydrochloride salts to their corresponding acetamides with trimethyl orthoacetate is described. Mechanistic studies using NMR and gas chromatography-mass spectrometry techniques indicate these reactions proceed via an O-methylimidate intermediate that undergoes in situ demethylation by chloride, affording the corresponding acetamides. Synthetically, this reaction represents a practical, high-yielding protocol with a simple workup for the rapid conversion of amine hydrochloride salts to acetamides.
- Di Grandi, Martin J.,Bennett, Caitlin,Cagino, Kristen,Muccini, Arnold,Suraci, Corey,Saba, Shahrokh
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supporting information
p. 2601 - 2607
(2015/11/28)
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- An attractive route to transamidation catalysis: Facile synthesis of new o-aryloxide-N-heterocyclic carbene ruthenium(II) complexes containing trans triphenylphosphine donors
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Well-defined robust ruthenium(II) complexes 3a-d bearing o-aryloxide-N-heterocyclic carbene ligands with different wingtip substituents (3a (R = Me), 3b (R = Ph), 3c (R = iPr) and 3d (R = Mes)) in the imidazole ring were synthesized in good yields by the reaction of imidazolium proligands with metal precursor [RuHCl(CO)(PPh3)3] by transmetallation from the corresponding silver carbene complexes. All the Ru(II)-NHC complexes have been characterized by elemental analyses, spectroscopic methods as well as ESI mass spectrometry. The molecular structure of the complex 3a was identified by means of single-crystal X-ray diffraction analysis, which revealed that the complexes possess a distorted octahedral geometry. In order to explore the catalytic potential of the synthesized complexes, all the four [Ru-NHC] complexes [3a-d] were tested as catalysts for transamidation of carboxamides with amines. Notably, the complex 3a was found to be very efficient and versatile catalyst toward transamidation of a wide range of amides with amines.
- Nirmala, Muthukumaran,Prakash, Govindan,Viswanathamurthi, Periasamy,Malecki, Jan Grzegorz
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- Designing of thermally stable amide functionalized benzimidazolium perchlorate ionic liquid for transamidation of primary carboxamides
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In the present work, we have designed and synthesized a thermally stable catalyst based on functionalized benzimidazolium perchlorate ionic liquid and tested its efficacy towards metal free and solvent free transamidation of amides and amines. The ionic liquid comprising the perchlorate ion has shown remarkably better activity than those which contain other anions and accordingly a plausible mechanism for the catalytic activity is arrived. The developed catalytic system has shown excellent activity towards the transamidation of alicyclic and aromatic amines with acetamide, benzamide and p-nitrobenzamide under mild conditions. Furthermore, the transamidation of nicotinamide with benzylamine in presence of the ionic liquid catalyst was found to occur with very good yields and thus provides a facile route for the synthesis of pharmaceutically significant compounds. The catalyst has exhibited very good thermal stability upto 203 °C and very good recyclability upto 5 runs without significant loss in its activity.
- Muskawar, Prashant Narayan,Thenmozhi,Bhagat, Pundlik Rambhau
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p. 158 - 167
(2015/09/28)
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- Generation and trapping of ketenes in flow
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Ketenes were generated by the thermolysis of alkoxyalkynes under flow conditions, and then trapped with amines and alcohols to cleanly give amides and esters. For a 10 min reaction time, temperatures of 180, 160, and 140 °C were required for >95% conversion of EtO, iPrO, and tBuO alkoxyalkynes, respectively. Variation of the temperature and flow rate with inline monitoring of the output by IR spectroscopy allowed the kinetic parameters for the conversion of 1-ethoxy-1-octyne to be easily estimated (Ea = 105.4 kJ/mol). Trapping of the in-situ-generated ketenes by alcohols to give esters required the addition of a tertiary amine catalyst to prevent competitive [2+2] addition of the ketene to the alkoxyalkyne precursor.
- Henry, Cyril,Bolien, David,Ibanescu, Bogdan,Bloodworth, Sally,Harrowven, David C.,Zhang, Xunli,Craven, Andy,Sneddon, Helen F.,Whitby, Richard J.
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p. 1491 - 1499
(2015/03/04)
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- Carbonylation of quaternary ammonium salts to tertiary amides using NaCo(CO)4 catalyst
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We reported here the catalytic carbonylation of quaternary ammonium salts under anhydrous condition. Quaternary ammonium salts, a kind of versatile reagents that were widely used in organometallic chemistry, can be carbonylated to tertiary amides by an in situ prepared NaCo(CO)4 catalyst. It was found that the counterions (Cl-, Br-, I-, OTf-) in the quaternary ammonium salts played a significant role in the reaction and tetramethylammonium iodide could give high yield (96%) of N,N-dimethylacetamide (DMAc) with only 0.5 mol% cobalt catalyst. Under optimum conditions, several other quaternary ammonium iodides were also carbonylated to corresponding tertiary amides in moderate to excellent yields. Obviously, these results also give us a special apprehension that Me4NI and other quaternary ammonium salts could be possibly carbonylated to tertiary amides in the carbonylation reaction where they are used as promoters or solvents in most cases. Considering the high activity and moderate to excellent selectivity, this process could be a potential method for the synthesis of certain tertiary amides. Moreover, the cleaving mechanism of CN bonds and the possible catalytic intermediates were discussed in detail.
- Lei, Yizhu,Zhang, Rui,Wu, Qing,Mei, Hui,Xiao, Bo,Li, Guangxing
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p. 120 - 125
(2013/12/04)
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- Palladium-catalyzed carbonylation of quaternary ammonium halides to tertiary amides
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Catalytic carbonylation of quaternary ammonium salts under anhydrous conditions was investigated using palladium catalyst. The carbonylation of tetramethylammonium iodide was chosen as a model reaction and studied systematically. Ligand-free PdCl2 showed efficient catalytic performance for this transformation. A palladium catalyst loading as low as 0.05 mol% was sufficient for high yield (96.9%) of N,N-dimethylacetamide, corresponding to a turnover frequency of 242 h-1. Under optimum conditions, several other quaternary ammonium halides were also carbonylated to corresponding tertiary amides in moderate to excellent yields. The catalytic activity of commercial palladium on activated carbon (Pd/C) catalyst was also evaluated. The Pd/C catalyst exhibited high activity for this carbonylation reaction and could be recycled six times with a slight decrease in activity. Furthermore, mechanistic considerations concerning Pd-catalyzed carbonylation of quaternary ammonium halides were also discussed. Copyright
- Lei, Yizhu,Zhang, Rui,Wu, Linjuan,Wu, Qing,Mei, Hui,Li, Guangxing
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p. 310 - 314
(2014/04/03)
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- Hydrogen bond organocatalysis of benzotriazole in transamidation of carboxamides with amines
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A new method of transamidation of carboxamides with amines catalyzed by benzotriazole has been developed.
- Nguyen, Thanh Binh,Ermolenko, Ludmila,Dau, Marie-Elise Tran Huu,Al-Mourabit, Ali
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p. 403 - 416
(2014/01/17)
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- Immobilization of Candida cylindracea lipase on poly lactic acid, polyvinyl alcohol and chitosan based ternary blend film: Characterization, activity, stability and its application for N-a
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The ecofriendly ternary blend polymer film was prepared from the chitosan (CH), polylactic acid (PLA) and polyvinyl alcohol (PVA). Immobilization of Candida cylindracea lipase (CCL) was carried out on ternary blend polymer via entrapment methodology. The ternary blend polymer and immobilized biocatalyst were characterized by using N2 adsorption-desorption isotherm, SEM, FTIR, DSC, and (%) water content analysis through Karl Fischer technique. Biocatalyst was then subjected for the determination of practical immobilization yield, protein loading and specific activity. Immobilized biocatalyst was further applied for the determination of biocatalytic activity for N-acylation reactions. Various reaction parameters were studied such as effect of immobilization support (ratio of PLA:PVA:CH), molar ratio (dibutylamine:vinyl acetate), solvent, biocatalyst loading, time, temperature, and orbital speed rotation. The developed protocol was then applied for the N-acylation reactions to synthesize several industrially important acetamides with excellent yields. Interestingly, immobilized lipase showed fivefold higher catalytic activity and better thermal stability than the crude extract lipase CCL. Furthermore various kinetic and thermodynamic parameters were studied and the biocatalyst was efficiently recycled for four successive reuses. It is noteworthy to mention that immobilized biocatalyst was stable for period of 300 days.
- Badgujar, Kirtikumar C.,Dhake, Kishor P.,Bhanage, Bhalchandra M.
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p. 1335 - 1347
(2013/09/12)
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- L-Proline: An efficient catalyst for transamidation of carboxamides with amines
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In the presence of a catalytic amount of l-proline (10 mol %), transamidations of carboxamides with amines were achieved under solvent-free conditions. The transamidation process is compatible with a wide range of amines.
- Rao, Sadu Nageswara,Mohan, Darapaneni Chandra,Adimurthy, Subbarayappa
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supporting information
p. 1496 - 1499
(2013/06/27)
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- Solvent free, highly chemoselective N and O-acylation on silica and silica magnesium oxide: A recyclable solid surface
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Silica or silica/magnesium oxide mixed surface mediates the N and O-acylation, benzoylation or sulfonylation of hosts of substrates under solvent free conditions at ambient temperature with high chemoselectivity.
- Ghosh, Pranab,Mandal, Amitava
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p. 261 - 268
(2012/10/29)
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- Optically active thiophenes via an organocatalytic one-pot methodology
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A general methodology for the synthesis of trisubstituted, optically active thiophenes by an organocatalytic one-pot reaction cascade is presented. The target products are synthesized in good yields (up to 92%) and with excellent enantioselectivities (up to 98% ee). Importantly, based on practical and easily available starting materials, the presented methodology can be conducted under mild reaction conditions. To further elucidate the generality, the synthesis of optically active thienoindoles, as well as selenophenes, is also demonstrated.
- Ransborg, Lars Krogager,Albrecht, Lukasz,Weise, Christian F.,Bak, Jesper R.,Jorgensen, Karl Anker
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supporting information; scheme or table
p. 724 - 727
(2012/04/11)
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- Novel double-SO3h functionalized ionic liquid for acetylation
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Novel double-SO3H functionalized ionic liquid (DFIL) was synthesized and its catalytic activities for acetylation studied. The result showed that the DFIL possess high acidity and was very efficient for the acetylation of alcohols, amines and phenols with good to excellent yields in short reaction times. Operational simplicity, stability to water and air, small amounts needed, low cost, high yields, high acidity, applicability to large-scale reactions and reusability are the key features of the DFIL, which indicated promising applications of DFIL in green chemical processes. Pleiades Publishing, Ltd., 2012.
- Zhu, Lili,Liang, Xuezheng
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p. 684 - 688
(2013/02/23)
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- Isopropenyl acetate, a remarkable, cheap and acylating agent of amines under solvent- and catalyst-free conditions: A systematic investigation
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Isopropenyl acetate was proved to be an efficient reagent for acetylation of amine in the absence of solvent and catalyst. The corresponding acetamides were obtained in very high yields without any purification.
- Pelagalli, Romina,Chiarotto, Isabella,Feroci, Marta,Vecchio, Stefano
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supporting information; experimental part
p. 2251 - 2255
(2012/09/08)
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- Transamidation of primary amides with amines catalyzed by zirconocene dichloride
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Zirconocene dichloride (Cp2ZrCl2) has been shown to be an effective catalyst for the transamidation of primary amides with amines in cyclohexane at 80°C in 5-24 hours. For favourable substrates, the reaction can be performed at temperatures as low as 30°C.
- Atkinson, Benjamin N.,Chhatwal, A. Rosie,Lomax, Helen V.,Walton, James W.,Williams, Jonathan M. J.
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supporting information
p. 11626 - 11628,3
(2012/12/12)
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- Transamidation of primary amides with amines catalyzed by zirconocene dichloride
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Zirconocene dichloride (Cp2ZrCl2) has been shown to be an effective catalyst for the transamidation of primary amides with amines in cyclohexane at 80°C in 5-24 hours. For favourable substrates, the reaction can be performed at temperatures as low as 30°C.
- Atkinson, Benjamin N.,Chhatwal, A. Rosie,Lomax, Helen V.,Walton, James W.,Williams, Jonathan M. J.
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supporting information
p. 11626 - 11628
(2013/01/15)
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- N -acyl DBN tetraphenylborate salts as N -acylating agents
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Air-stable and crystalline N-acyl DBN tetraphenylborate salts have been synthesized from 1,5-diazabicyclo[4.3.0]non-5-ene (DBN) and the corresponding acyl chloride in the presence of sodium tetraphenylborate. The salts have been shown to be effective N-acylating agents, reacting with primary amines, secondary amines, and sulfonamides to form the corresponding N-acylated products in good yields. The DBN hydrotetraphenylborate byproduct can be conveniently removed by filtration, providing pure N-acylated products without the need for further purification. The N-acyl DBN tetraphenylborate salts are attractive alternatives to acyl halides as they can be stored in air without decomposition, avoid the production of free acid during acylation reactions, and can be used under more forcing thermal conditions.
- Taylor, James E.,Jones, Matthew D.,Williams, Jonathan M. J.,Bull, Steven D.
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experimental part
p. 2808 - 2818
(2012/04/23)
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- Amorphous carbon-silica composites bearing sulfonic acid as solid acid catalysts for the chemoselective protection of aldehydes as 1,1-diacetates and for N-, O- and S-acylations
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Amorphous carbon-silica composites bearing sulfonic acid derived from inexpensive natural organic compounds (glucose, maltose, cellulose, chitosan and starch) were prepared by partial carbonization followed by sulfonation and their catalytic activity was evaluated for the protection of aldehydes as 1,1-diacetates and for N-, O- and S-acylations under solvent-free conditions. Different biomaterials have been chosen, with a view to select the most active solid acid catalyst. Carbon-silica composites were characterized by FTIR, XRD and elemental analysis. Sulfonated carbon-silica composite derived from starch was found to be the most active and could be recycled for several runs without loss of significant activity. It was also characterized by TGA, SEM and TEM.
- Gupta, Princy,Paul, Satya
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experimental part
p. 2365 - 2372
(2011/10/31)
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- Poly-(N,N′-dibromo-N-ethyl-benzene-1,3-disulfonamide) and N,N,N′,N′- tetrabromobenzene-1,3-disulfonamide as highly efficient catalysts, and (AC2O/SIO2) as a heterogeneous system for the acetylation of alcohols, amines, and thiols under microwave irradiation
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Chemical Equation Presented Poly-(N,N′-dibromo-N-ethyl-benzene-1,3- disulfonamide) (PBBS) and N,N,N′,N′-tetrabromobenzene-1,3- disulfonamide (TBBDA) are good activators and catalytic reagents for the acetylation of alcohols, amines, and thiols. The presented method has the advantages of mild conditions, chemoselectivity, and good to high yields, and uses noncorrosive, inexpensive, recyclable, and environmentally friendly catalysts. We have also demonstrated that combining SiO2 with microwave energy provides an efficient, fast, convenient, and easy workup procedure for the synthesis of mono- and disubstituted acetates, acetamides, and thioacetamides. Copyright Taylor & Francis Group, LLC.
- Veisi, Hojat,Ghorbani-Vaghei, Ramin,Eskandari, Hosna,Hemmati, Saba,Rezaei, Ardashir,Hajinazari, Somaye,Far, Mohammad Raoof Heidari,Entezari, Azam
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experimental part
p. 213 - 219
(2011/04/24)
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- Reactions of aryl acetates with secondary alicyclic amines in ethanol/water mixtures: Effect of the solvent composition on the kinetics and mechanism
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We report a kinetic study on the reactions of secondary alicyclic amines toward 4-nitrophenyl, 2,4-dinitrophenyl, and 2,4,6-trinitrophenyl acetates (1, 2, and 3) in ethanol/water mixtures of different compositions. It is found that (i) the intermediate in the reaction of 1 is stabilized in a mixture of 90 vol% ethanol; (ii) for the reaction of 2, the mechanism is stepwise in water but concerted in the mixtures; (iii) For the reaction of 3, the mechanism is concerted along the whole range of composition; (iv) the effect of -NO 2 outweighs the solvent effect; (v) preferential solvation in the core of reaction can be ruled out.
- Castro, Enrique A.,Millan, Daniela,Aguayo, Raul,Campodonico, Paola R.,Santos, Jose G.
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supporting information; experimental part
p. 687 - 693
(2012/07/27)
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- Synthesis of amides from esters and amines with liberation of H2 under neutral conditions
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Efficient synthesis of amides directly from esters and amines is achieved under mild, neutral conditions with the liberation of molecular hydrogen. Both primary and secondary amines can be utilized. This unprecedented, general, environmentally benign reaction is homogeneously catalyzed under neutral conditions by a dearomatized ruthenium-pincer PNN complex and proceeds in toluene under an inert atmosphere with a high turnover number (up to 1000). PNP analogues do not catalyze this transformation, underlining the crucial importance of the amine arm of the pincer ligand. A mechanism is proposed involving metal-ligand cooperation via aromatization-dearomatization of the pyridine moiety and hemilability of the amine arm.
- Gnanaprakasam, Boopathy,Milstein, David
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supporting information; experimental part
p. 1682 - 1685
(2011/04/22)
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- A green approach to chemoselective N-acetylation of amines using catalytic amount of zinc acetate in acetic acid under microwave irradiation
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It has been found for the first time that zinc acetate alone can act as a selective A'-acetylating agent without any solvent under closed vessel microwave irradiation. It is also observed that the use of a catalytic amount of this reagent in acetic acid is sufficient enough for smooth running of A'-acetylation of a number of structurally diverse amines, and the reaction is chemoselective with respect to phenols, thiols, acids and alcohols. Herein is reported a simple, efficient, cost-effective and environmentally benign alternative method for chemoselective A'-acetylation of amines using catalytic amount of zinc acetate in acetic acid under microwave irradiation. The reaction procedure requires no other solvent, and is rapid with good to excellent yields.
- Brahmachari,Laskar,Sarkar
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experimental part
p. 1274 - 1281
(2010/12/24)
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- Additive-free chemoselective acylation of amines
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Aliphatic and aromatic amines are efficiently acylated by acetic, pivalic, benzoic, phthalic, or maleic anhydrides in ethyl acetate at room temperature. Under the same experimental conditions, amino alcohols are chemoselectively acylated at the amino group.
- Temperini, Andrea,Terlizzi, Raffaella,Testaferri, Lorenzo,Tiecco, Marcello
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experimental part
p. 295 - 302
(2010/03/30)
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- Hepatitis C Virus Inhibitors
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This disclosure concerns novel compounds of Formula (I) as defined in the specification and compositions comprising such novel compounds. These compounds are useful antiviral agents, especially in inhibiting the function of the NS5A protein encoded by Hepatitis C virus (HCV). Thus, the disclosure also concerns a method of treating HCV related diseases or conditions by use of these novel compounds or a composition comprising such novel compounds.
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Page/Page column 48
(2010/10/19)
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