- Synthesis, characterization, and reactivity of the first hafnium alkyl complex stabilized by amidate ligands
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A photo and thermally stable bis(amidate)-dibenzyl complex of Hf ([ DMP(NO)Ph]2Hf(CH2Ph) 2(THF) (2a) was formed as a monosolvated THF adduct in near quantitative yield from Hf(CH2Ph)4
- Thomson, Robert K.,Patrick, Brian O.,Schafer, Laurel L.
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- Buchwald-Hartwig cross-coupling of amides (transamidation) by selective N-C(O) cleavage mediated by air- And moisture-stable [Pd(NHC)(allyl)Cl] precatalysts: Catalyst evaluation and mechanism
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The Pd-NHC-catalyzed acyl-type Buchwald-Hartwig cross-coupling of amides by N-C(O) cleavage (transamidation) provides a valuable alternative to the classical methods for amide synthesis. Herein, we report a combined experimental and computational study of the Buchwald-Hartwig cross-coupling of amides using well-defined, air- and moisture-stable [Pd(NHC)(allyl)Cl] precatalysts. Most crucially, we present a comprehensive evaluation of a series of distinct Pd(ii)-NHC precatalysts featuring different NHC scaffolds and throw-away ligands for the synthesis of functionalized amides that are not compatible with stoichiometric transition-metal-free transamidation methods. Furthermore, we present evaluation of the catalytic cycle by DFT methods for a series of different Pd(ii)-NHC precatalysts. The viability of accessing NHC-supported acyl-palladium(ii) amido complexes will have implications for the design and development of cross-coupling methods involving stable amide electrophiles.
- Li, Guangchen,Zhou, Tongliang,Poater, Albert,Cavallo, Luigi,Nolan, Steven P.,Szostak, Michal
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- Catalyst-free synthesis of phenanthridinesviaelectrochemical coupling of 2-isocyanobiphenyls and amines
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Catalyst free synthesis of 6-aryl phenanthridines and amides through an electrochemical reaction is reported in this study. The coupling reaction proceeds by the cathodic reduction ofin situformed diazonium ions, which are formed from anilines and an alkyl nitrite. The generated aryl radical diazonium ions coupled from isocyanides furnished the desired products in good yields. This cascade reaction was conducted in an undivided cell equipped with an RVC as the anode and Pt as the cathode usingnBu4NBF4as the electrolyte at room temperature. A series of detailed mechanistic studies have also been performed, including a radical clock experiment and cyclic voltammetry analysis.
- Malviya, Bhanwar Kumar,Singh, Karandeep,Jaiswal, Pradeep K.,Karnatak, Manvika,Verma, Ved Prakash,Badsara, Satpal Singh,Sharma, Siddharth
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p. 6367 - 6378
(2021/04/16)
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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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- A case study of Pd?Pd intramolecular interaction in a benzothiazole based palladacycle; catalytic activity toward amide synthesisviaan isocyanide insertion pathway
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An acetate bridge benzothiazolepalladacycle containing a rare metallophilic intramolecular Pd?Pd interaction was synthesized and thoroughly characterized. The synthesized benzothiazolepalladacycle directly anchored on SBA-15 to form an efficient heterogen
- Loni, Masood,Balmohammadi, Yaser,Dadgar Yeganeh, Reza,Imani, Kaveh,Notash, Behrouz,Bazgir, Ayoob
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supporting information
p. 3290 - 3297
(2021/02/26)
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- Copper and N-Heterocyclic Carbene-Catalyzed Oxidative Amidation of Aldehydes with Amines
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A one-pot two-step oxidative process has been developed for the tert-butyl hydroperoxide mediated transformation of aldehydes and amines into amides catalyzed by copper(I) iodide and an N-heterocyclic carbene. The process is additive-free and does not require the amine to be transformed into its hydrochloride salts. The method is simple and practicable, has a broad substrate scope, and uses economical, feasible, and abundant reagents.
- Singh, Ashmita,Narula, Anudeep Kumar
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supporting information
p. 718 - 722
(2021/02/26)
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- Sterically hindered (pyridyl)benzamidine palladium(II) complexes: Syntheses, structural studies, and applications as catalysts in the methoxycarbonylation of olefins
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Reactions of ligands (E)-N′-(2,6-diisopropylphenyl)-N-(4-methylpyridin-2-yl)benzimidamide (L1), (E)-N′-(2,6-diisopropylphenyl)-N-(6-methylpyridin-2-yl)benzimidamide (L2), (E)-N′-(2,6-dimethylphenyl)-N-(6-methylpyridin-2-yl)benzimidamide (L3), (E)-N′-(2,6-dimethylphenyl)-N-(4-methylpyridin-2-yl)benzimidamide (L4), and (E)-N-(6-methylpyridin-2-yl)-N′-phenylbenzimidamide (L5) with [Pd(NCMe)2Cl2] furnished the corresponding palladium(II) precatalysts (Pd1–Pd5), in good yields. Molecular structures of Pd2 and Pd3 revealed that the ligands coordinate in a N^N bidentate mode to afford square planar compounds. Activation of the palladium(II) complexes with para-tolyl sulfonic acid (PTSA) afforded active catalysts in the methoxycarbonylation of a number of alkene. The resultant catalytic activities were controlled by the both the complex structure and alkene substrate. While aliphatic substrates favored the formation of linear esters (>70%), styrene substrate resulted in the formation of predominantly branched esters of up to 91%.
- Akiri, Saphan O.,Ojwach, Stephen O.
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- Direct Amidation of Esters by Ball Milling**
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The direct mechanochemical amidation of esters by ball milling is described. The operationally simple procedure requires an ester, an amine, and substoichiometric KOtBu and was used to prepare a large and diverse library of 78 amide structures with modest to excellent efficiency. Heteroaromatic and heterocyclic components are specifically shown to be amenable to this mechanochemical protocol. This direct synthesis platform has been applied to the synthesis of active pharmaceutical ingredients (APIs) and agrochemicals as well as the gram-scale synthesis of an active pharmaceutical, all in the absence of a reaction solvent.
- Barreteau, Fabien,Battilocchio, Claudio,Browne, Duncan L.,Godineau, Edouard,Leitch, Jamie A.,Nicholson, William I.,Payne, Riley,Priestley, Ian
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supporting information
p. 21868 - 21874
(2021/09/02)
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- N -Heterocyclic carbene (NHC) catalyzed amidation of aldehydes with amines via the tandem N -hydroxysuccinimide ester formation
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A facile method for the amidation of aldehydes by a cascade approach was developed. This methodology, reported for the first time, uses a N-heterocyclic carbene (NHC) as the catalyst, and N-hydroxysuccinimide (NHS) mediated synthesis of amides utilising TBHP as the oxidant. Various substituted aldehydes reacted smoothly with NHS giving the corresponding active esters in moderate to good yields, which facilely converted into amides in one pot. In addition, the drug moclobemide was synthesized to represent the practical utility of the developed methodology. This journal is
- Singh, Ashmita,Narula
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p. 7486 - 7490
(2021/05/13)
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- Rhodium-Catalyzed Addition of Organozinc Iodides to Carbon-11 Isocyanates
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Amides were prepared using rhodium-catalyzed coupling of organozinc iodides and carbon-11 (11C, t1/2 = 20.4 min) isocyanates. Nonradioactive isocyanates and sp3 or sp2 organozinc iodides generated amides in yields of 13%-87%. Incorporation of cyclotron-produced [11C]CO2 into 11C-amide products proceeded in yields of 5%-99%. The synthetic utility of the methodology was demonstrated through the isolation of [11C]N-(4-fluorophenyl)-4-methoxybenzamide ([11C]6g) with a molar activity of 267 GBq μmol-1 and 12% radiochemical yield in 21 min from the beginning of synthesis.
- Fouad, Moustafa H.,Ismailani, Uzair S.,Mair, Braeden A.,Munch, Maxime,Rotstein, Benjamin H.
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p. 2746 - 2750
(2020/04/16)
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- 3,6-Di(pyridin-2-yl)-1,2,4,5-tetrazine (pytz) catalysed metal-free amide bond formation from thioacids and amines at room temperature
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A 3,6-di(pyridin-2-yl)-1,2,4,5-tetrazine (pytz) catalysed efficient, mild and metal-free method has been developed for direct amide bond synthesis from simple thioacids and amines as starting materials. This methodology is useful for aromatic, aliphatic, and heteroaromatic thioacids as well as primary, secondary, heterocyclic, and even functionalized amines. A wide substrates scope, operationally mild conditions, and acylation of amines without affecting other functional groups such as alcohols, esters, carbodithioates, among others make this strategy very attractive and practical.
- Samanta, Suvendu,Ray, Shounak,Bhaduri, Samanka Narayan,Samanta, Partha Kumar,Biswas, Papu
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supporting information
(2020/08/10)
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- Chiral Br?nsted Acid from Chiral Phosphoric Acid Boron Complex and Water: Asymmetric Reduction of Indoles
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A new chiral Br?nsted acid, generated in situ from a chiral phosphoric acid boron (CPAB) complex and water, was successfully applied to asymmetric indole reduction. This “designer acid catalyst”, which is more acidic than TsOH as suggested by DFT calculations, allows the unprecedented direct asymmetric reduction of C2-aryl-substituted N-unprotected indoles and features good to excellent enantioselectivities with broad functional group tolerance. DFT calculations and mechanistic experiments indicates that this reaction undergoes C3-protonation and hydride-transfer processes. Besides, bulky C2-alkyl-substituted N-unprotected indoles are also suitable for this system.
- Yang, Kai,Lou, Yixian,Wang, Chenglan,Qi, Liang-Wen,Fang, Tongchang,Zhang, Feng,Xu, Hetao,Zhou, Lu,Li, Wangyang,Zhang, Guan,Yu, Peiyuan,Song, Qiuling
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supporting information
p. 3294 - 3299
(2020/01/21)
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- Catalyst-Free, Metal-Free, and Chemoselective Transamidation of Activated Secondary Amides
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A simple protocol, which is catalyst-free, metal-free, and chemoselective, for transamidation of activated secondary amides in ethanol as solvent under mild conditions is reported. A wide range of amines, amino acids, amino alcohols, and the substituents, which are problematic in catalyzed transamidation, are tolerated in this methodology. The transamidation reaction was successfully extended to water as the medium as well. The present methodology appears to be better than the other catalyzed transamidations reported recently.
- Ramkumar, Rajagopal,Chandrasekaran, Srinivasan
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p. 921 - 932
(2019/02/10)
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- Clickable coupling of carboxylic acids and amines at room temperature mediated by SO2F2: A significant breakthrough for the construction of amides and peptide linkages
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The construction of amide bonds and peptide linkages is one of the most fundamental transformations in all life processes and organic synthesis. The synthesis of structurally ubiquitous amide motifs is essential in the assembly of numerous important molecules such as peptides, proteins, alkaloids, pharmaceutical agents, polymers, ligands and agrochemicals. A method of SO2F2-mediated direct clickable coupling of carboxylic acids with amines was developed for the synthesis of a broad scope of amides in a simple, mild, highly efficient, robust and practical manner (>110 examples, >90% yields in most cases). The direct click reactions of acids and amines on a gram scale are also demonstrated using an extremely easy work-up and purification process of washing with 1 M aqueous HCl to provide the desired amides in greater than 99% purity and excellent yields.
- Wang, Shi-Meng,Zhao, Chuang,Zhang, Xu,Qin, Hua-Li
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p. 4087 - 4101
(2019/04/30)
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- Well-Defined, Air-Stable, and Readily Available Precatalysts for Suzuki and Buchwald-Hartwig Cross-coupling (Transamidation) of Amides and Esters by N-C/O-C Activation
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A general class of well-defined, air-stable, and readily available Pd(II)-NHC precatalysts (NHC = N-heterocyclic carbene) for Suzuki and Buchwald-Hartwig cross-coupling of amides (transamidation) and esters by selective N-C/O-C cleavage is reported. Since these precatalysts are highly active and the easiest to synthesize, the study clearly suggests that [Pd(NHC)(acac)Cl] should be routinely included during the development of new cross-coupling methods. An assay for in situ screening of NHC salts in this cross-coupling manifold is presented.
- Zhou, Tongliang,Li, Guangchen,Nolan, Steven P.,Szostak, Michal
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supporting information
p. 3304 - 3309
(2019/05/10)
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- Structure-activity relationships for highly potent half-sandwich organoiridium(III) anticancer complexes with C^N-chelated ligands
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We herein report the synthesis, characterization, catalytic ability in converting coenzyme NADH to NAD+ and anticancer activity of half-sandwich iridium(III) complexes, [(η5-Cpxbiph)Ir(C^N)Cl]PF6 ?, where Cpxbiph = tetramethyl(biphenyl)cyclopentadienyl, C^N = varying imine-N-heterocyclic carbene ligands. The molecular structure of [(η5-Cpxbiph)Ir(L6)Cl]PF6 (complex Ir6), exhibiting the familiar “piano-stool” geometry, has been authenticated by X-ray crystallography. The anticancer activities of these complexes can be governed via substituent effects of three tunable domains and the ligand substituted variants offer an effective chelate ligand set that distinguishes anticancer activity and catalytic ability. Notably, complex Ir6 displays the greatest cytotoxic activities (IC50 = 0.85 μM), whose anticancer activity is more approximately 25-fold higher than that of cisplatin. The initial cell death mechanistic insight displays that this group of iridium(III) complexes exerts anticancer effects via cell cycle arrest, apoptosis induction and loss of the mitochondrial membrane potential. In addition, the confocal microscopy imaging shows that the complex Ir6 can damage lysosome. Overall, preliminary structure–activity relationships study and understanding of the cell death mechanism perhaps provide a rational strategy for enhancing anticancer activity of this family of complexes.
- Yang, Yuliang,Guo, Lihua,Ge, Xingxing,Shi, Shaopeng,Gong, Yuteng,Xu, Zhishan,Zheng, Xiaofeng,Liu, Zhe
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- Isoprene Polymerization with Pyrazolylimine Cobalt(II) Complexes: Manipulation of 3,4-Selectivities by Ligand Design and Use of Triphenylphosphine
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A series of pyrazolylimine CoCl2 complexes were synthesized and well characterized. The single crystal structures and coordination geometries of these complexes were confirmed by X-ray diffraction, which revealed dimeric and monomeric structure
- Fang, Liang,Zhao, Wenpeng,Han, Chao,Liu, Heng,Hu, Yanming,Zhang, Xuequan
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p. 609 - 616
(2019/01/24)
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- Highly Chemoselective, Transition-Metal-Free Transamidation of Unactivated Amides and Direct Amidation of Alkyl Esters by N-C/O-C Cleavage
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The amide bond is one of the most fundamental functional groups in chemistry and biology and plays a central role in numerous processes harnessed to streamline the synthesis of key pharmaceutical and industrial molecules. Although the synthesis of amides is one of the most frequently performed reactions by academic and industrial scientists, the direct transamidation of tertiary amides is challenging due to unfavorable kinetic and thermodynamic contributions of the process. Herein, we report the first general, mild, and highly chemoselective method for transamidation of unactivated tertiary amides by a direct acyl N-C bond cleavage with non-nucleophilic amines. This operationally simple method is performed in the absence of transition metals and operates under unusually mild reaction conditions. In this context, we further describe the direct amidation of abundant alkyl esters to afford amide bonds with exquisite selectivity by acyl C-O bond cleavage. The utility of this process is showcased by a broad scope of the method, including various sensitive functional groups, late-stage modification, and the synthesis of drug molecules (>80 examples). Remarkable selectivity toward different functional groups and within different amide and ester electrophiles that is not feasible using existing methods was observed. Extensive experimental and computational studies were conducted to provide insight into the mechanism and the origins of high selectivity. We further present a series of guidelines to predict the reactivity of amides and esters in the synthesis of valuable amide bonds by this user-friendly process. In light of the importance of the amide bond in organic synthesis and major practical advantages of this method, the study opens up new opportunities in the synthesis of pivotal amide bonds in a broad range of chemical contexts.
- Li, Guangchen,Ji, Chong-Lei,Hong, Xin,Szostak, Michal
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supporting information
p. 11161 - 11172
(2019/08/07)
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- Versatile One-Pot Synthesis of Polysubstituted Cyclopent-2-enimines from α,β-Unsaturated Amides: Imino-Nazarov Reaction
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The imino-Nazarov cyclization of the polysubstituted pentan-1,4-diene-3-imines was realized. To this aim, a one-pot procedure involving reductive alkenyliminylation of α,β-unsaturated secondary amides with potassium organotrifluoroborates, followed by acid-catalyzed imino-Nazarov cyclization of the polysubstituted pentan-1,4-diene-3-imine intermediates, was studied systematically. This mild, operationally simple, flexible, and high-yielding protocol efficiently affords polysubstituted pentan-1,4-diene-3-imines, cyclopentenimines, and α-amino cyclopentenones, which are useful scaffolds in organic synthesis. The substituent effect at the C2 position of the polysubstituted pentan-1,4-diene-3-imines was studied by means of density-functional theory calculations. Results suggested that the electron-donating group facilitates the imino-Nazarov cyclization process.
- Fan, Ting,Wang, Ao,Li, Jia-Qi,Ye, Jian-Liang,Zheng, Xiao,Huang, Pei-Qiang
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supporting information
p. 10352 - 10356
(2018/07/30)
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- Visible light driven amide synthesis in water at room temperature from Thioacid and amine using CdS nanoparticles as heterogeneous Photocatalyst
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Highly efficient photocatalytic thioacid mediated amide synthesis at room temperature using CdS nanoparticles as photocatalyst was observed under a household 30?W CFL in water. The operationally mild reaction was tolerant to a number of functional group substitutions on amine and could be scaled up to gram. This heterogeneous photocatalyst was extremely stable and could easily be recovered by simple centrifugation for at least six recycling reactions without any significant loss of catalytic performance. The possible reaction mechanism for the photocatalytic thioacid mediated amide synthesis over the CdS semiconductor has also been proposed on the basis of experimental observations.
- Das, Sudipto,Ray, Shounak,Ghosh, Abhisek Brata,Samanta, Partha Kumar,Samanta, Suvendu,Adhikary, Bibhutosh,Biswas, Papu
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- Synthesis of Benzamide Derivatives by the Reaction of Arenes and Isocyanides through a C-H Bond Activation Strategy
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A carbon-carbon bond formation reaction between isocyanides and benzene derivatives is reported. In contrast to traditional cross-coupling reactions, which require aryl halides or pseudohalides, we use a palladium catalyst to generate the aryl-palladium through C-H bond activation of arenes. This method offers an attractive approach to a range of benzamides from readily accessible benzene derivatives.
- Khalaj, Mehdi,Taherkhani, Mahboubeh,Mousavi-Safavi, Seyed Mahmoud,Akbari, Jafar
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- Novel and Versatile Imine-N-Heterocyclic Carbene Half-Sandwich Iridium(III) Complexes as Lysosome-Targeted Anticancer Agents
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We, herein, report the synthesis, characterization, luminescence properties, anticancer, and antibacterial activities of a family of novel half-sandwich iridium(III) complexes of the general formula [(n5-Cpx)Ir(C^N)Cl]PF6- [Cpx = pentamethylcyclopentadienyl (Cp) or tetramethyl(biphenyl)-cyclopentadienyl (Cpxbiph)] bearing versatile imine-N-heterocyclic carbene ligands. In this complex framework, substituents on four positions could be modulated, which distinguishes this class of complex and provides a large amount of flexibility and opportunity to tune the cytotoxicity of complexes. The X-ray crystal structures of complexes 4 and 10 exhibit the expected "piano-stool" geometry. With the exception of 1, 2, and 11, each complex shows potent cytotoxicity, with IC50 (half-maximum inhibitory concentration) values ranging from 1.99 to 25.86 μM toward A549 human lung cancer cells. First, the effect of four positions bearing different substituents in the complex framework on the anticancer activity, that is, structure-activity relationship, was systematically studied. Complex 8 (IC50 = 1.99 μM) displays the highest anticancer activities, whose cytotoxicity is more than 10-fold higher than that of the clinical platinum drug cisplatin against A549 cancer cells. Second, their chemical reactivity including nucleobases binding, catalytic activity in converting coenzyme NADH to NAD+, reaction with glutathione (GSH), and bovine serum albumin (BSA) binding is investigated. No reaction with nucleobase is observed. However, these iridium(III) complexes bind rapidly to GSH and can catalyze oxidation of NADH to NAD+. In addition, they show moderate binding affinity to BSA and the fluorescence quenching of BSA by the iridium (III) complexes is due to the static quenching. Third, the mode of cell death was also explored through flow cytometry experiments, including cell cycle, apoptosis induction, reactive oxygen species (ROS) and mitochondrial membrane potential. It seems that cell cycle perturbation, apoptosis induction, increase of ROS level and loss of mitochondrial membrane potential together contribute to the anticancer potency of these complexes. Last, the use of confocal microscopy provides insights into the microscopic mechanism that the typical and most active complex 8 enters A549 lung cancer cells mainly through energy-dependent pathway and is located in lysosome. Furthermore, lysosome damage and nuclear morphology were detected by confocal microscopy. Nuclear condensation and apoptotic bodies may finally induce cells apoptosis. Interestingly, complex 8 also shows antibacterial activity against Gram-positive Staphylococcus aureus. This work may provide an alternative and effective strategy to smart design of potent organometallic half-sandwich iridium(III) anticancer drugs.
- Yang, Yuliang,Guo, Lihua,Tian, Zhenzhen,Gong, Yuteng,Zheng, Hongmei,Zhang, Shumiao,Xu, Zhishan,Ge, Xingxing,Liu, Zhe
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p. 11087 - 11098
(2018/09/14)
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- Imine-N-Heterocyclic Carbenes as Versatile Ligands in Ruthenium(II) p-Cymene Anticancer Complexes: A Structure–Activity Relationship Study
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A family of novel imine-N-heterocyclic carbene ruthenium(II) complexes of the general formula [(η6-p-cymene)Ru(C^N)Cl]PF6? (where C^N is an imine-N-heterocyclic carbene chelating ligand with varying substituents) have been prepared and characterized. In this imine-N-heterocyclic carbene chelating ligand framework, there are three potential sites that can be modified, which distinguishes this class of ligand and provides a body of flexibilities and opportunities to tune the cytotoxicity of these ruthenium(II) complexes. The influence of substituent effects of three tunable domains on the anticancer activity and catalytic ability in converting coenzyme NADH to NAD+ is investigated. This family of complexes displays an exceedingly distinct anticancer activity against A549 cancer cells, despite their close structural similarity. Complex 9 shows the highest anticancer activity in this series against A549 cancer cells (IC50=14.36 μm), with an approximately 1.5-fold better activity than the clinical platinum drug cisplatin (IC50=21.30 μm) in A549 cancer cells. Mechanistic studies reveal that complex 9 mediates cell death mainly through cell stress, including cell cycle arrest, inducing apoptosis, increasing intracellular reactive oxygen species (ROS) levels, and depolarization of the mitochondrial membrane potential (MMP). Furthermore, lysosomal damage is also detected by confocal microscopy.
- Yang, Yuliang,Guo, Lihua,Tian, Zhenzhen,Liu, Xicheng,Gong, Yuteng,Zheng, Hongmei,Ge, Xingxing,Liu, Zhe
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p. 2923 - 2933
(2018/09/12)
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- Amine Activation: N-Arylamino Acid Amide Synthesis from Isothioureas and Amino Acids
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N-arylamino acid amides have been synthesized via a novel method based on N-arylamine activation into isothioureas followed by reaction with amino acids under iron catalysis. The activated N-arylamines are easily prepared using a three-component reaction with commercial reagents, tert-butylisocyanide and S-phenyl benzenethiosulfonate. The protocol shows a broad functional group compatibility, with respect to side chain functionality of the amino acid (e. g. aliphatic and aromatic OH, (hetero)aromatic NH, amide NH, thioether), and the chiral amino acids do not undergo epimerization. The mechanism of the new amide synthesis has been studied. (Figure presented.).
- Zhu, Yan-Ping,Mampuys, Pieter,Sergeyev, Sergey,Ballet, Steven,Maes, Bert U. W.
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p. 2481 - 2498
(2017/07/22)
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- Bu4NI-Catalyzed Oxygen-Centered Radical Addition between Acyl Peroxides and Isocyanides
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A novel oxygen-centered radical addition between acyl peroxides and isocyanides has been developed. A diverse collection of valuable arylcarboxyamides were easily synthesized by this protocol. From the preliminary mechanistic study, the elimination of carbon dioxide affords the product via an intramolecular rearrangement.
- Chen, Meng,Li, Yang,Tang, Hong,Ding, Hao,Wang, Kai,Yang, Lingen,Li, Cuiting,Gao, Meng,Lei, Aiwen
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supporting information
p. 3147 - 3150
(2017/06/23)
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- A General Method for Two-Step Transamidation of Secondary Amides Using Commercially Available, Air- and Moisture-Stable Palladium/NHC (N-Heterocyclic Carbene) Complexes
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The first general method is reported for transamidation of secondary carboxamides catalyzed by Pd-NHC (NHC = N-heterocyclic carbene) complexes. Commercially available, air- and moisture-stable (NHC)Pd(R-allyl)Cl complexes can effect C-N cross-coupling of a wide range of N-Boc and N-Ts amides, obtained by selective amide N-functionalization, with non-nucleophilic anilines and sterically hindered amines in very good yields. The first use of versatile Pd-NHC complexes as catalysts is represented for transition-metal-catalyzed C(acyl)-N amination of amides by N-C activation.
- Meng, Guangrong,Lei, Peng,Szostak, Michal
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p. 2158 - 2161
(2017/04/27)
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- Pd-PEPPSI: A general Pd-NHC precatalyst for Buchwald-Hartwig cross-coupling of esters and amides (transamidation) under the same reaction conditions
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Amides are of fundamental interest in many fields of chemistry involving organic synthesis, chemical biology and biochemistry. Here, we report the first catalytic Buchwald-Hartwig coupling of both common esters and amides by highly selective C(acyl)-X (X = O, N) cleavage to rapidly access aryl amide functionality via a cross-coupling strategy. Reactions are promoted by versatile, easily prepared, well-defined Pd-PEPPSI type precatalysts, and proceed in good to excellent yields and with excellent chemoselectivity for the acyl bond cleavage. The method is user friendly because it employs commercially-available, moisture- and air-stable precatalysts. Notably, for the first time we demonstrate selective C(acyl)-N and C(acyl)-O cleavage/Buchwald-Hartwig amination under the same reaction conditions, which allows for streamlining amide synthesis by avoiding restriction to a particular acyl metal precursor. Of broad interest, this study opens the door to using a family of well-defined Pd(ii)-NHC precatalysts bearing pyridine "throw-away" ligands for the selective C(acyl)-amination of bench-stable carboxylic acid derivatives.
- Shi, Shicheng,Szostak, Michal
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supporting information
p. 10584 - 10587
(2017/09/29)
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- PROCESS FOR DIRECT AMIDATION OF AMINES VIA RH(I)-CATALYZED ADDITION OF BOROXINES
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This invention relates to a process for making an amide by directly reacting a ferf-butyloxycarbonyl or carboxybenzyl N substituted amine with a boroxine derivative in the presence of a rhodium(l) catalyst, in the presence of a solvent an optionally in the presence of a base. The process provides means to react protected amines to amides using th boroganic reagent without the deprotection of an amine such that it can be directly converted from protected form in on step, and results in good yields in amide formation even for sterically hindered amines. Potassium fluoride is the preferre base in the reaction run in dioxane. Typical rhodium catalysts that can be used include rhodium(l) complex monomer and dimers such as chloro(1,5-cyclooctadiene) rhodium(l) dimer ("[CI(cod)Rh]2") or bis(1,5-cyclooctadiene)rhodium(l trifluoromethanesulfonate ("(cod)2Rh(OTf)").
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Page/Page column 9; 12
(2017/03/28)
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- Exploiting the Reactivity of Isocyanide: Coupling Reaction between Isocyanide and Toluene Derivatives Using the Isocyano Group as an N1 Synthon
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An unusual oxidative coupling reaction of isocyanide and toluene derivatives using tetrabutylammonium iodide (TBAI) as a catalyst is disclosed. The experimental results and mechanistic study show that the isocyano group acts formally as an N1 synthon during the transformation, thus expanding the reactivity profile of isocyanide.
- Liu, Zhiqiang,Zhang, Xinglu,Li, Jian,Li, Jianxiong,Li, Feng,Li, Chunju,Jia, Xueshun
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p. 4052 - 4055
(2016/08/30)
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- Direct Amidation of N-Boc- and N-Cbz-Protected Amines via Rhodium-Catalyzed Coupling of Arylboroxines and Carbamates
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N-Boc- and N-Cbz-protected amines are directly converted into amides by a novel rhodium-catalyzed coupling of arylboroxines and carbamates, replacing the traditional two-step deprotection-condensation sequence. Both protected anilines and aliphatic amines are efficiently transformed into a wide variety of secondary benzamides, including sterically hindered and electron-deficient amides, as well as in the presence of acid-labile and reducible functional groups.
- Lim, Diane S. W.,Lew, Tedrick T. S.,Zhang, Yugen
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p. 6054 - 6057
(2016/01/09)
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- Copper(i)-catalyzed amidation reaction of organoboronic esters and isocyanates
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A simple and efficient methodology for the preparation of amides from easily available organoboronic esters and isocyanates has been accomplished using a ligand-free copper(i) catalyst. The reaction system demonstrated a broad substrate scope and provided convenient access to a wide variety of secondary amides.
- Salim Lew, Tedrick Thomas,Wen Lim, Diane Shu,Zhang, Yugen
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p. 5140 - 5143
(2015/12/05)
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- Chloroform as a Carbon Monoxide Precursor: In or Ex Situ Generation of CO for Pd-Catalyzed Aminocarbonylations
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Conditions for the rapid hydrolysis of chloroform to carbon monoxide (CO) using heterogeneous CsOH·H2O are described. CO and 13CO can be generated cleanly and rapidly under mild conditions and can be captured either in or ex situ in palladium-catalyzed aminocarbonylation reactions. Utilizing only 1-3 equiv of CO allows for the aminocarbonylation of aryl, vinyl, and benzyl halides with a wide variety of primary and secondary amines giving amide products in good to excellent yields. (Chemical Equation Presented).
- Gockel, Samuel N.,Hull, Kami L.
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supporting information
p. 3236 - 3239
(2015/07/15)
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- Phosphine-free atmospheric carbonylation of aryl iodides with aniline derivatives in the presence of a reusable silica-supported palladium catalyst
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Various palladium catalysts were obtained by the immobilisation of palladium on silica, modified with imidazolium salts. The efficiency of the catalysts was greatly dependent on the choice of the anion of the imidazolium salt, the palladium precursor and on the conditions of heterogenisation. Palladium acetate immobilised on silica with grafted imidazolium chloride moieties was shown to be a selective and recyclable catalyst for atmospheric aminocarbonylation of aryl iodides with aromatic amines in DMF. It was proved that the greater loss of palladium in DMSO can be explained by the formation of soluble palladium complexes.
- Urbán, Béla,Papp, Máté,Srankó, Dávid,Skoda-F?ldes, Rita
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p. 150 - 157
(2015/02/19)
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- Copper-catalyzed oxidative amidation between aldehydes and arylamines under mild conditions
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A facile strategy to prepare amide bonds has been developed. A series of amide compounds, including heterocyclic amide compounds, were obtained with moderate to good yields ranging from 31-88% by using copper iodide (CuI) to catalyze the oxidative amidation between aldehydes and amines under solvent-free conditions at room temperature in air.
- Ding, Yongzheng,Zhang, Xian,Zhang, Dongyang,Chen, Yuting,Wu, Zhibing,Wang, Peiyi,Xue, Wei,Song, Baoan,Yang, Song
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supporting information
p. 831 - 833
(2015/02/19)
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- Phosphanyl Methanimine (PCN) Ligands for the Selective Trimerization/Tetramerization of Ethylene with Chromium
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1-Phosphanyl methanimine ligands, R2P-C(Ph)=NR′, may be prepared via a modular, convergent synthesis in good overall yield. Coordination chemistry studies with chromium confirm that they bind in a bidentate κ2-P,N mode. In combination with chromium and an activator, these ligands promote the selective oligomerization of ethylene to 1-hexene and 1-octene with high activity. Notably, an exceptionally high liquid fraction selectivity to saleable products (1-hexene + 1-octene) is observed (>95%), along with a potent ligand dependence, such that selectivity can be varied from pure trimerization through to mixed trimerisation/tetramerisation with a 1-octene:1-hexene (OTH) ratio of 1.7.
- Radcliffe, James E.,Batsanov, Andrei S.,Smith, David M.,Scott, John A.,Dyer, Philip W.,Hanton, Martin J.
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p. 7095 - 7098
(2015/12/11)
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- Synthesis of amides via copper-catalyzed amidation of aryl halides using isocyanides
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An efficient method for intermolecular CC cross-coupling reactions between isocyanides and aryl halides, catalyzed by copper(I) oxide, is developed. This transformation serves as a direct method for the preparation of benzamides in aqueous DMSO, in moderate to good yields.
- Yavari, Issa,Ghazanfarpour-Darjani, Majid,Bayat, Mohammad J.
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p. 4981 - 4982
(2015/01/09)
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- Design, synthesis and structure-activity relationship of new HSL inhibitors guided by pharmacophore models
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Hormone-sensitive lipase (HSL) is a critical enzyme involved in the hormonally regulated release of fatty acids and glycerol from adipocyte lipid stores. Its inhibition may improve insulin sensitivity and blood glucose handling in type 2 diabetes. Accordingly, many small-molecule HSL inhibitors have recently been identified. In continuation of our efforts for discovery of new HSL inhibitors, we prepared a variety of esters, amides, sulfonamides and sulfonate esters capable of fitting two pharmacophore models that we developed and published earlier. The tested compounds were synthesized via coupling reactions of aroyl chlorides or sulfonyl chlorides with phenols, amines and related derivatives. Our efforts led to the identification of interesting compounds of low micromolar anti-HSL bioactivities, which have potential to be developed into effective antidiabetic agents.
- Al-Shawabkeh, Jumana D.,Al-Nadaf, Afaf H.,Dahabiyeh, Lina A.,Taha, Mutasem O.
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p. 127 - 145
(2014/03/21)
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- A palladium-catalyzed carbonylation approach to acid chloride synthesis
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We describe a new approach to acid chloride synthesis via the palladium-catalyzed carbonylation of aryl iodides. The combination of sterically encumbered phosphines (PtBu3) and CO coordination has been found to facilitate the rapid carbonylation of aryl iodides into acid chlorides via reductive elimination from (tBu3P)(CO) Pd(COAr)Cl. The formation of acid chlorides can also be exploited to perform traditional aminocarbonylation reactions under exceptionally mild conditions (ambient temperature and pressure), and with a range of weakly nucleophilic substrates.
- Quesnel, Jeffrey S.,Arndtsen, Bruce A.
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supporting information
p. 16841 - 16844
(2013/12/04)
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- Yttrium (amidate) complexes for catalytic C-N bond formation. Rapid, room temperature amidation of aldehydes
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Yttrium (amidate) precatalysts are highly active for the mild amidation of aldehydes with amines. Reactions occur at room temperature within 5 min in up to 98% isolated yield. These rare-earth systems are effective for this transformation in the absence of supplementary heat, light, base, or oxidants. The reaction proceeds with functionalized amines and/or aldehydes. A comparison of various amidate precatalysts in combination with reaction monitoring suggests that the targeted amide products formed during the reaction promote the formation of alternative catalytically active amidate species in situ.
- Thomson, Jaclyn A.,Schafer, Laurel L.
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experimental part
p. 7897 - 7904
(2012/08/07)
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- Copper-catalyzed selective benzylic C-O cyclization of N-o-tolylbenzamides: Synthesis of 4 H-3,1-benzoxazines
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A novel Selectfluor-mediated copper-catalyzed highly selective benzylic C-O cyclization for the synthesis 4H-3,1-benzoxazines is reported. The predominant selectivity for a benzylic C(sp3)-H over an aromatic C(sp 2)-H bond in N-o-tolylbenzamides is achieved.
- Li, Yan,Li, Zhongshu,Xiong, Tao,Zhang, Qian,Zhang, Xiangyang
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supporting information; body text
p. 3522 - 3525
(2012/08/08)
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- Metal-free synthesis of amides by oxidative amidation of aldehydes with amines in PEG/oxidant system
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A simple, inexpensive, and efficient one-pot synthesis of amide derivatives were achieved in good to excellent yields via the directly oxidative amidation of aldehydes with amines under PEG/Oxidant system.
- Liang, Jun,Lv, Jing,Shang, Zhi-Cai
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supporting information; experimental part
p. 8532 - 8535
(2011/11/12)
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- Coupling of ortho-substituted aryl chlorides with bulky amides
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Voluminous amides were coupled with deactivated, sterically hindered aryl chlorides in excellent yields providing products, which have not been efficiently accessible by transition metal catalysis so far. Application of an unsymmetric bisphosphine ligand was critical for the high catalytic activity.
- Falk, Florian C.,Froehlich, Roland,Paradies, Jan
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supporting information; experimental part
p. 11095 - 11097
(2011/11/07)
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- Synthesis of amides via palladium-catalyzed amidation of aryl halides
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A new and efficient method for the synthesis of amides via palladium-catalyzed C-C coupling of aryl halides with isocyanides is reported, by which a series of amides were formed from readily available starting materials under mild conditions. This transformation could extend its use to the synthesis of natural products and significant pharmaceuticals.(Figure Presented)
- Jiang, Huanfeng,Liu, Bifu,Li, Yibiao,Wang, Azhong,Huang, Huawen
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supporting information; experimental part
p. 1028 - 1031
(2011/04/27)
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- Investigation of ligand steric effects on a highly cis-selective Rh(i) cyclopropanation catalyst
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Four new Rh(i) complexes bearing chelating imine-functionalized N-heterocyclic carbene ligands have been synthesized and characterized. The catalytic activity of these new Rh(i) complexes has been tested in the cyclopropanation reaction between ethyl diazoacetate and styrene. One of the new complexes, having ethyl groups on the ligand N-aryl ring, exhibited a reactivity and a cis-diastereoselectivity that were comparable to our previously reported Rh(i) cyclopropanation catalyst of this type, and a higher yield and cis-diastereoselectivity were obtained at lower catalyst loadings and higher temperatures. The other new Rh(i) complexes were found to be inferior to the previously reported Rh(i) cyclopropanation catalyst. The catalytic study gave important information about the effect that changing the steric requirements of the substituents at the ligand system has on the efficiency and cis-diastereoselectivity of the complexes as cyclopropanation catalysts.
- Rosenberg, Marianne Lenes,Langseth, Eirin,Krivokapic, Alexander,Gupta, Nalinava Sen,Tilset, Mats
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scheme or table
p. 2306 - 2313
(2011/12/03)
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- Synthesis of amides through the Cannizzaro-type reaction catalyzed by lanthanide chlorides
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Amidation of aldehydes with lithium amides through the LnCl3-catalyzed Cannizzaro-type reactions afforded a variety of amides in high yields. The electronic and steric effects on the reaction were investigated. The features of the economical ca
- Zhang, Lijun,Su, Shunpeng,Wu, Hongping,Wang, Shaowu
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supporting information; experimental part
p. 10022 - 10024
(2010/02/27)
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- Highly cis-Selective cyclopropanations with ethyl diazoacetate using a novel Rh(I) catalyst with a chelating n-heterocyclic iminocarbene ligand
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(Chemical Equation Presented) A structurally characterized Rh(I) iminocarbene complex (N,C)Rh(CO)Cl is activated with AgOTf to act as a highly cis-selective catalyst for the cyclopropanation of substituted styrenes and other alkenes with ethyl diazoacetate (11 examples, 10-99% yield, up to >99% cis-selectivity).
- Rosenberg, Marianne Lenes,Krivokapic, Alexander,Tilset, Mats
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scheme or table
p. 547 - 550
(2009/08/07)
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- Anxiolytic-like effects of N,N-dialkyl-2-phenylindol-3-ylglyoxylamides by modulation of translocator protein promoting neurosteroid biosynthesis
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Novel N,N-disubstituted indol-3-ylglyoxylamides (1-56), bearing different combinations of substituents R1-R5, were synthesized and evaluated as ligands of the translocator protein (TSPO), the 18 kDa protein representing the minimal f
- Da Settimo, Federico,Simorini, Francesca,Taliani, Sabrina,La Motta, Concettina,Marini, Anna Maria,Salerno, Silvia,Bellandi, Marusca,Novellino, Ettore,Greco, Giovanni,Cosimelli, Barbara,Da Pozzo, Eleonora,Costa, Barbara,Simola, Nicola,Morelli, Micaela,Martini, Claudia
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supporting information; experimental part
p. 5798 - 5806
(2009/08/07)
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- Novel quinolizidinyl derivatives as antiarrhythmic agents
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Eighteen analogues of lidocaine, mexiletine, and procainamide were synthesized, replacing their aminoalkyl chains with the rigid and cumbersome quinolizidine nucleus. The target compounds were tested for antiarrhythmic, inotropic, and chronotropic effects
- Vazzana, Iana,Budriesi, Roberta,Terranova, Emanuela,Ioan, Pierfranco,Ugenti, Maria Paola,Tasso, Bruno,Chiarini, Alberto,Sparatore, Fabio
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p. 334 - 343
(2007/10/03)
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- Palladium-catalyzed silane/siloxane reductions in the one-pot conversion of nitro compounds into their amines, hydroxylamines, amides, sulfonamides, and carbamates
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A combination of palladium(II) acetate, aqueous potassium fluoride, and polymethylhydrosiloxane (PMHS) facilitates the room-temperature reduction of aromatic nitro compounds to anilines. These reactions tend to be quick (30 min), high-yielding, and tolerate a range of other functional groups. Replacement of PMHS/KF with triethylsilane allows for the reduction of aliphatic nitro compounds to their corresponding hydroxylamines. Depending on the substrate, both conditions can allow for the in situ conversion of the product amines into amides, sulfonamides, and carbamates. Georg Thieme Verlag Stuttgart.
- Rahaim Jr., Ronald J.,Maleczka Jr., Robert E.
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p. 3316 - 3340
(2008/09/17)
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- Intramolecular charge transfer with N-benzoylaminonaphthalenes. 1-Aminonaphthalene versus 2-aminonaphthalene as electron donors
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N-(substituted-benzoyl)-1-aminonaphthalenes and N-(substituted-benzoyl)-2-aminonaphthalenes (1-NBAs and 2-NBAs) with varied substituents at the para- or meta-position of benzoylphenyl ring were prepared to probe the difference between 1-aminonaphthalene (1-AN) and 2-aminonaphthalene (2-AN) as electron donors, using benzanilide-like charge transfer as a probe reaction. An abnormal long-wavelength emission was found for all of the prepared aminonaphthalene derivatives in cyclohexane and was assigned to the CT state by the observation of a substantial red shift with increasing solvent polarity or with increasing electron-withdrawing ability of the substituent. The CT emission energies were found to follow a linear relationship with the Hammett constant of the substituent and the value of the linear slope for 1-NBAs (-0.45 eV) was higher than that of 2-NBAs(-0.35 eV), the latter being close to that of the aniline derivatives (BAs, -0.345 eV). This pointed to a higher extent of charge separation in the CT state of 1-NBAs in which a full charge separation was established by the reduction potential dependence of the CT emission energy with a linear slope of -1.00. The possible contribution of the difference in the steric effect and the electron donating ability of the donors in 1-NBAs and 2-NBAs was ruled out by the observation that the corresponding linear slopes of benzoyl-substituted BAs remained unchanged when para-, meta-, ortho-, or ortho, ortho-methyls were introduced into the aniline moiety. It was therefore concluded that 1-AN enhanced the charge transfer in 1-NBAs and the proximity of its 1La and 1Lb states was suggested to be responsible. Results showed that the charge transfers in 1-NBAs and 2-NBAs were not the same and 1-AN and 2-AN as electron donors were different not only in electron donating ability but in shaping the charge transfer pathways as well.
- Zhang, Xuan,Liu, Chun-Hua,Liu, Li-Hong,Wu, Fang-Ying,Guo, Lin,Sun, Xiang-Ying,Wang, Chao-Jie,Jiang, Yun-Bao
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p. 728 - 732
(2007/10/03)
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