- Design, synthesis, in vitro determination and molecular docking studies of 4-(1-(tert-butyl)-3-phenyl-1H-pyrazol-4-yl) pyridine derivatives with terminal sulfonamide derivatives in LPS-induced RAW264.7 macrophage cells
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In the present work, a new series of 4-(1-(tert-butyl)-3-phenyl-1H-pyrazol-4-yl) pyridine possessing terminal ethyl or propyl sulfonamides was designed and synthesized. The cytotoxic effect of the final compounds was measured by applying MTT assay in LPS-Induced RAW264.7 macrophage cells. The final target compounds were screened for their anti-inflammatory effect through their ability to inhibit NO and PGE2 production and cytokines production (TNF-α, IL-6, IL-1β) in LPS-induced RAW264.7 macrophage at 10 μM concentration. Compounds 8d, 9d, and 9k showed the highest inhibitory effect on NO production. Compounds 8d and 9k exhibited high PGE2 inhibition with IC50 values of 3.47, 2.54 μM, respectively. Compounds 8d and 9k exhibited high cytokines inhibition ≥60%. The most potent compounds 8d and 9k were tested to determine their effect on iNOS and COX-2 mRNA expression level. Compound 9k activity on iNOS and COX-2 proteins level, pro-inflammatory mediators and cytokines was determined and showed remarkable inhibition for both proteins level. Compounds 8d, 9k showed high binding affinity to COX-2 active site and exhibited similar binding interactions of the native ligand celecoxib. [Figure not available: see fulltext.]
- Mersal, Karim I.,Abdel-Maksoud, Mohammed S.,Ali, Eslam M. H.,Ammar, Usama M.,Zaraei, Seyed-Omar,Kim, Jae-Min,Kim, Su-Yeon,Lee, Kyung-Tae,Lee, Kwan Hyi,Kim, Si-Won,Park, Hyun-Mee,Ji, Mi-Jung,Oh, Chang-Hyun
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p. 1925 - 1942
(2021/08/30)
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- GPR52 Antagonist Reduces Huntingtin Levels and Ameliorates Huntington's Disease-Related Phenotypes
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GPR52 is an orphan G protein-coupled receptor (GPCR) that has been recently implicated as a potential drug target of Huntington's disease (HD), an incurable monogenic neurodegenerative disorder. In this research, we found that striatal knockdown of GPR52 reduces mHTT levels in adult HdhQ140 mice, validating GPR52 as an HD target. In addition, we discovered a highly potent and specific GPR52 antagonist Comp-43 with an IC50 value of 0.63 μM by a structure-activity relationship (SAR) study. Further studies showed that Comp-43 reduces mHTT levels by targeting GPR52 and promotes survival of mouse primary striatal neurons. Moreover, in vivo study showed that Comp-43 not only reduces mHTT levels but also rescues HD-related phenotypes in HdhQ140 mice. Taken together, our study confirms that inhibition of GPR52 is a promising strategy for HD therapy, and the GPR52 antagonist Comp-43 might serve as a lead compound for further investigation.
- Wang, Congcong,Zhang, Yu-Fang,Guo, Shimeng,Zhao, Quan,Zeng, Yanping,Xie, Zhicheng,Xie, Xin,Lu, Boxun,Hu, Youhong
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p. 941 - 957
(2020/11/30)
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- Sequential Ir/Cu-Mediated Method for the Meta-Selective C-H Radiofluorination of (Hetero)Arenes
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This article describes a sequential Ir/Cu-mediated process for the meta-selective C-H radiofluorination of (hetero)arene substrates. In the first step, Ir-catalyzed C(sp2)-H borylation affords (hetero)aryl pinacolboronate (BPin) esters. The intermediate organoboronates are then directly subjected to copper-mediated radiofluorination with [18F]tetrabutylammonium fluoride to afford fluorine-18 labeled (hetero)arenes in high radiochemical yield and radiochemical purity. This entire process is performed on a benchtop without Schlenk or glovebox techniques and circumvents the need to isolate (hetero)aryl boronate esters. The reaction was automated on a TracerLab FXFN module with 1,3-dimethoxybenzene and a meta-tyrosine derivative. The products, [18F]1-fluoro-3,5-dimethoxybenzene and an 18F-labeled meta-tyrosine derivative, were obtained in 37 ± 5% isolated radiochemical yield and >99% radiochemical purity and 25% isolated radiochemical yield and 99% radiochemical purity, and 0.52 Ci/μmol (19.24 GBq/μmol) molar activity (Am), respectively.
- Wright, Jay S.,Sharninghausen, Liam S.,Preshlock, Sean,Brooks, Allen F.,Sanford, Melanie S.,Scott, Peter J. H.
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supporting information
p. 6915 - 6921
(2021/05/29)
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- Synthesis, biological evaluation of benzothiazole derivatives bearing a 1,3,4-oxadiazole moiety as potential anti-oxidant and anti-inflammatory agents
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Twenty benzothiazole derivatives bearing a 1,3,4-oxadiazole moiety were synthesized and evaluated for their anti-oxidant and anti-inflammatory activities. Among these compounds, 8h and 8l were appeared to have high radical scavenging efficacies as 0.05 ± 0.02 and 0.07 ± 0.03 mmol/L of IC50 values in ABTS+[rad] bioassay, respectively. In anti-inflammatory tests, compound 8h displayed good activity with 57.35% inhibition after intraperitoneal administration, which was more potent than the reference drug (indomethacin). Molecular modeling studies were performed to investigate the binding mode of the representative compound 8h into COX-2 enzyme. In vitro enzyme study implied that compound 8h exerted its anti-inflammatory activity through COX-2 inhibition.
- Bai, Xue-Qian,Cui, Ming-Yue,Li, Chun-Shi,Liang, Cheng-Wu,Song, Ze-Wen,Wang, Hui-Yan,Zhang, Tian-Yi,Zheng, Xian-Jing
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- Discovery of [1,2,4]triazole derivatives as new metallo-β-lactamase inhibitors
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The emergence and spread of metallo-β-lactamase (MBL)-mediated resistance to β-lactam antibacterials has already threatened the global public health. A clinically useful MBL inhibitor that can reverse β-lactam resistance has not been established yet. We here report a series of [1,2,4]triazole derivatives and analogs, which displayed inhibition to the clinically relevant subclass B1 (Verona integron-encoded MBL-2) VIM-2. 3-(4-Bromophenyl)-6,7-dihydro-5H-[1,2,4]triazolo [3,4-b][1,3]thiazine (5l) manifested the most potent inhibition with an IC50 (half-maximal inhibitory concentration) value of 38.36 μM. Investigations of 5l against other B1 MBLs and the serine β-lactamases (SBLs) revealed the selectivity to VIM-2. Molecular docking analyses suggested that 5l bound to the VIM-2 active site via the triazole involving zinc coordination and made hydrophobic interactions with the residues Phe61 and Tyr67 on the flexible L1 loop. This work provided new triazole-based MBL inhibitors and may aid efforts to develop new types of inhibitors combating MBL-mediated resistance.
- Yuan, Chen,Yan, Jie,Song, Chen,Yang, Fan,Li, Chao,Wang, Cheng,Su, Huiling,Chen, Wei,Wang, Lijiao,Wang, Zhouyu,Qian, Shan,Yang, Lingling
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- Ruthenium-catalyzed hydrogenation of CO2as a route to methyl esters for use as biofuels or fine chemicals
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A novel robust diphosphine-ruthenium(ii) complex has been developed that can efficiently catalyze both the hydrogenation of CO2 to methanol and its in situ condensation with carboxylic acids to form methyl esters; a TON of up to 3260 is achievable for the CO2 to methanol step. Both aromatic and aliphatic carboxylic acids can be transformed to their corresponding methyl esters with high conversion and selectivity (17 aliphatic and 18 aromatic examples). On the basis of a series of experiments, a mechanism has been proposed to account for the various steps involved in the catalytic pathway. More importantly, this approach provides a promising route for using CO2 as a C1 source for the production of biofuels, fine chemicals and methanol.
- Li, Yong,Liu, Qingbin,Ma, Yanping,Solan, Gregory A.,Sun, Wen-Hua,Wang, Zheng,Zhang, Qiuyue,Zhao, Ziwei,Zhong, Yanxia
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p. 6766 - 6774
(2020/08/25)
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- Palladium-Catalyzed, Copper(I)-Promoted Methoxycarbonylation of Arylboronic Acids with O-Methyl S-Aryl Thiocarbonates
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Here, we report O-methyl S-aryl thiocarbonates as a versatile esterification reagent for palladium-catalyzed methoxycarbonylation of arylboronic acid in the presence of copper(I) thiophene-2-carboxylate (CuTC). The reaction condition is mild, and a variety of substituents including sensitive-Cl,-Br, and free-NH2 could be tolerated. Further applications in the late-stage esterification of some pharmaceutical drugs demonstrate the broad utility of this method.
- Cao, Ya-Fang,Li, Ling-Jun,Liu, Min,Xu, Hui,Dai, Hui-Xiong
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p. 4475 - 4481
(2020/04/10)
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- 1,3-Dibromo-5,5-dimethylhydantoin as a Precatalyst for Activation of Carbonyl Functionality
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Activation of carbonyl moiety is one of the most rudimentary approaches in organic synthesis and is crucial for a plethora of industrial-scale condensation reactions. In esterification and aldol condensation, which represent two of the most important reactions, the susceptibility of the carbonyl group to nucleophile attack allows the construction of a variety of useful organic compounds. In this context, there is a constant need for development of and improvement in the methods for addition-elimination reactions via activation of carbonyl functionality. In this paper, an advanced methodology for the direct esterification of carboxylic acids and alcohols, and for aldol condensation of aldehydes using widely available, inexpensive, and metal-free 1,3-dibromo-5,5-dimethylhydantoin under neat reaction conditions is reported. The method is air- and moisture-tolerant, allowing simple synthetic and isolation procedures for both reactions presented in this paper. The reaction pathway for esterification is proposed and a scale-up of certain industrially important derivatives is performed.
- ?ebular, Klara,Bo?i?, Bojan ?.,Stavber, Stojan
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supporting information
(2019/08/01)
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- SAR Studies on Aromatic Acylhydrazone-Based Inhibitors of Fungal Sphingolipid Synthesis as Next-Generation Antifungal Agents
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Recently, the fungal sphingolipid glucosylceramide (GlcCer) synthesis has emerged as a highly promising new target for drug discovery of next-generation antifungal agents, and we found two aromatic acylhydrazones as effective inhibitors of GlcCer synthesis based on HTP screening. In the present work, we have designed libraries of new aromatic acylhydrazones, evaluated their antifungal activities (MIC80 and time-kill profile) against C. neoformans, and performed an extensive SAR study, which led to the identification of five promising lead compounds, exhibiting excellent fungicidal activities with very large selectivity index. Moreover, two compounds demonstrated broad spectrum antifungal activity against six other clinically relevant fungal strains. These five lead compounds were examined for their synergism/cooperativity with five clinical drugs against seven fungal strains, and very encouraging results were obtained; e.g., the combination of all five lead compounds with voriconazole exhibited either synergistic or additive effect to all seven fungal strains.
- Del Poeta, Maurizio,Haranahalli, Krupanandan,Lazzarini, Cristina,Mallamo, John,McCarthy, J. Brian,Ojima, Iwao,Pathiranage, Senuri,Sun, Yi,Zambito, Julia
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- Aldehydes as potential acylating reagents for oxidative esterification by inorganic ligand-supported iron catalysis
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The oxidative esterification of various aldehydes with alcohols could be achieved by a heterogeneous iron(iii) catalyst supported on a ring-like POM inorganic ligand under mild conditions, affording the corresponding esters, including several drug molecules and natural products, in high yields. ESI-MS and control experiments demonstrated that POM-FeV(O) was the active catalytic species and the plausible mechanism was presented. More importantly, the 6th run of the iron catalyst recycles shows only a slight decrease in the yield.
- Yu, Han,Wang, Jingjing,Wu, Zhikang,Zhao, Qixin,Dan, Demin,Han, Sheng,Tang, Jiangjiang,Wei, Yongge
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supporting information
p. 4550 - 4554
(2019/08/21)
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- Esterification of aryl/alkyl acids catalysed by n-bromosuccinimide under mild reaction conditions
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N-halosuccinimides (NXSs) are well-known to be convenient, easily manipulable and low-priced halogenation reagents in organic synthesis. In the present work, N-bromosuccinimide (NBS) has been promoted as the most efficient and selective catalyst among the NXSs in the reaction of direct esterification of aryl and alkyl carboxylic acids. Comprehensive esterification of substituted benzoic acids, mono-, di- and tri-carboxy alkyl derivatives has been performed under neat reaction conditions. The method is metal-free, air- and moisture-tolerant, allowing for a simple synthetic and isolation procedure as well as the large-scale synthesis of aromatic and alkyl esters with yields up to 100%. Protocol for the recycling of the catalyst has been proposed.
- ?ebular, Klara,Bo?i?, Bojan ?.,Stavber, Stojan
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- A biocatalytic method for the chemoselective aerobic oxidation of aldehydes to carboxylic acids
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Herein, we present a study on the oxidation of aldehydes to carboxylic acids using three recombinant aldehyde dehydrogenases (ALDHs). The ALDHs were used in purified form with a nicotinamide oxidase (NOx), which recycles the catalytic NAD+ at the expense of dioxygen (air at atmospheric pressure). The reaction was studied also with lyophilised whole cell as well as resting cell biocatalysts for more convenient practical application. The optimised biocatalytic oxidation runs in phosphate buffer at pH 8.5 and at 40 °C. From a set of sixty-one aliphatic, aryl-Aliphatic, benzylic, hetero-Aromatic and bicyclic aldehydes, fifty were converted with elevated yield (up to >99%). The exceptions were a few ortho-substituted benzaldehydes, bicyclic heteroaromatic aldehydes and 2-phenylpropanal. In all cases, the expected carboxylic acid was shown to be the only product (>99% chemoselectivity). Other oxidisable functionalities within the same molecule (e.g. hydroxyl, alkene, and heteroaromatic nitrogen or sulphur atoms) remained untouched. The reaction was scaled for the oxidation of 5-(hydroxymethyl)furfural (2 g), a bio-based starting material, to afford 5-(hydroxymethyl)furoic acid in 61% isolated yield. The new biocatalytic method avoids the use of toxic or unsafe oxidants, strong acids or bases, or undesired solvents. It shows applicability across a wide range of substrates, and retains perfect chemoselectivity. Alternative oxidisable groups were not converted, and other classical side-reactions (e.g. halogenation of unsaturated functionalities, Dakin-Type oxidation) did not occur. In comparison to other established enzymatic methods such as the use of oxidases (where the concomitant oxidation of alcohols and aldehydes is common), ALDHs offer greatly improved selectivity.
- Knaus, Tanja,Tseliou, Vasilis,Humphreys, Luke D.,Scrutton, Nigel S.,Mutti, Francesco G.
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p. 3931 - 3943
(2018/09/11)
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- Mechanistic Insights into Aerobic Oxidative Methyl Esterification of Primary Alcohols with Heterogeneous PdBiTe Catalysts
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Aerobic oxidative methyl esterification of primary alcohols is an important chemical transformation that converts a nucleophile (alcohol) into a versatile electrophile (methyl ester). We recently discovered a heterogeneous PdBiTe/C catalyst that exhibits the highest activity yet reported for this transformation. Bi and Te serve as synergistic promoters that enhance both the rate and yield of the reactions relative to reactions employing Pd alone or Pd in combination with Bi or with Te as the sole promoter. Here, we report a mechanistic study of the oxidative methyl esterification of benzyl alcohol and 1-octanol to provide insights into the overall multistep transformation as well as the role of the Bi and Te in the reaction. The catalytic rates of the oxidative esterification of benzyl alcohol and octanol with Pd, PdBi, PdTe, and PdBiTe catalysts exhibit a saturation dependence on [alcohol] and [K2CO3] and a first-order dependence on pO2. Hammett studies of benzyl alcohol oxidation reveal opposing electronic trends for initial rates of oxidation of alcohol to aldehyde (negative ? value) and the oxidation of aldehyde to methyl ester (positive ? value). These data and complementary kinetic isotope effect data support a Langmuir-Hinshelwood mechanism in which a surface-bound alkoxide or hemiacetal intermediate undergoes rate-limiting β-hydride elimination. Molecular oxygen participates in this process, as revealed by a first-order dependence on pO2. X-ray photoelectron and X-ray absorption spectroscopic methods show that the promoters undergo oxidation in preference to Pd, maintaining the Pd surface in the active metallic state and preventing inhibition by surface Pd-oxide formation. Collectively, these results provide valuable insights into the synergistic benefits of multiple promoters in heterogeneous catalytic oxidation reactions.
- Mannel, David S.,King, Jesaiah,Preger, Yuliya,Ahmed, Maaz S.,Root, Thatcher W.,Stahl, Shannon S.
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p. 1038 - 1047
(2018/02/14)
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- Cobalt-entrenched N-, O-, and S-tridoped carbons as efficient multifunctional sustainable catalysts for base-free selective oxidative esterification of alcohols
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We report the synthesis of sustainable and reusable non-noble transition-metal (cobalt) nanocatalysts containing N-, O-, and S-tridoped carbon nanotube (Co@NOSC) composites. The expensive and benign carrageenan served as the source of carbon, oxygen, and sulfur, whereas urea served as the nitrogen source. The material was prepared via direct mixing of precursors and freeze-drying followed by carbonization under nitrogen at 900 °C. Co@NOSC catalysts comprising a Co inner core and outer electron-rich heteroatom-doped carbon shell were thoroughly characterized using various techniques, namely, TEM, HRTEM, STEM elemental mapping, XPS, BET, and ICP-MS. The utility of the Co@NOSC catalyst was explored for base-free selective oxidative esterification of alcohols to the corresponding esters under mild reaction conditions; excellent conversions (up to 97%) and selectivities (up to 99%) were discerned. Furthermore, the substrate scope was explored for the cross-esterification of benzyl alcohol with long-chain alcohols (up to 98%) and lactonization of diols (up to 68%). The heterogeneous nature and stability of the catalyst facilitated by its ease of separation for long-term performance and recycling studies showed that the catalyst was robust and remained active even after six recycling experiments. EPR measurements were performed to deduce the reaction mechanism in the presence of POBN (α-(4-pyridyl-1-oxide)-N-tert-butylnitrone) as a spin-trapping agent, which confirmed the formation of CH2OH radicals and H radicals, wherein the solvent plays an active role in a nonconventional manner. A plausible mechanism was proposed for the oxidative esterification of alcohols on the basis of EPR findings. The presence of a cobalt core along with cobalt oxide and the electron-rich N-, O-, and S-doped carbon shell displayed synergistic effects to afford good to excellent yields of products.
- Nandan, Devaki,Zoppellaro, Giorgio,Med?ík, Ivo,Aparicio, Claudia,Kumar, Pawan,Petr, Martin,Tomanec, Ond?ej,Gawande, Manoj B.,Varma, Rajender S.,Zbo?il, Radek
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p. 3542 - 3556
(2018/08/07)
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- Oxalic acid as the: In situ carbon monoxide generator in palladium-catalyzed hydroxycarbonylation of arylhalides
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An efficient palladium-catalyzed hydroxycarbonylation reaction of arylhalides using oxalic acid as a CO source has been developed. The reaction features high safety, low catalyst loading, and a broad substrate scope, and provides a safe and tractable approach to access a variety of aromatic carboxylic acid compounds. Mechanistic studies revealed the decomposition pattern of oxalic acid.
- Shao, Changdong,Lu, Ailan,Wang, Xiaoling,Zhou, Bo,Guan, Xiaohong,Zhang, Yanghui
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supporting information
p. 5033 - 5040
(2017/07/10)
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- Synthesis and Biological Evaluation of New (-)-Gossypol-Derived Schiff Bases and Hydrazones
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A series of 14 new (-)-gossypol Schiff bases and hydrazones have been synthesized via an in situ procedure in high yields. Structural data showed that all target compounds exist as the enamine tautomer. Bioassays showed that several compounds exhibited cytotoxic effects against three human cancer cell lines. Compound 8a showed the greatest cytotoxic effect against hepatocellular carcinoma (HepG2), lung carcinoma (LU-1), and breast cancer (MCF-7) cell lines with IC50 values of 20.93, 13.58, and 9.40 μM, respectively. However, in an antibacterial test, compounds 8a and 8b inhibited Staphylococcus aureus and Bacillus cereus and compound 8e inhibited only Staphylococcus aureus at the same MIC values of 1024 μg/ml.
- Vu, Vu Van,Nhung, Trinh Thi,Thanh, Nguyen Thi,Chinh, Luu Van,Tien, Vu Dinh,Thuy, Vu Thu,Thi Thao, Do,Nam, Nguyen Hai,Koeckritz, Angela,Vu, Tran Khac
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- Efficient and selective palladium-catalyzed direct oxidative esterification of benzylic alcohols under aerobic conditions
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A highly efficient palladium-catalyzed approach for the direct oxidative esterification of benzylic alcohols with methanol and long-chain aliphatic alcohols under mild conditions has been achieved. This practical catalyst system exhibits a broad substrate scope and good functional group tolerance. Catalytic amount of Bi(OTf)3 is used as co-catalyst to improve the activity and selectivity of the reactions. A variety of esters are obtained in yields of 43–96%.
- Hu, Yongke,Li, Bindong
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p. 7301 - 7307
(2017/11/29)
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- Discovery of multicomponent heterogeneous catalysts via admixture screening: PdBiTe catalysts for aerobic oxidative esterification of primary alcohols
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In the present study, we demonstrate the utility of "admixture screening" for the discovery of new multicomponent heterogeneous Pd catalyst compositions that are highly effective for aerobic oxidative methyl esterification of primary alcohols. The identification of possible catalysts for this reaction was initiated by the screening of simple binary and ternary admixtures of Pd/charcoal in combination with one or two metal and/or metalloid components as the catalyst. This approach permitted rapid evaluation of over 400 admixture combinations for the oxidative methyl esterification of 1-octanol at 60°C in methanol. Product yields from these reactions varied widely, ranging from 2% to 88%. The highest yields were observed with Bi-, Te-, and Pb-based additives, and particularly from those containing both Bi and Te. Validation of the results was achieved by preparing specific PdBiTe catalyst formulations via a wet-impregnation method, followed by application of response surface methodology to identify the optimal Pd-Bi-Te catalyst stoichiometry. This approach revealed two very effective catalyst compositions: PdBi0.47Te0.09/C (PBT-1) and PdBi0.35Te0.23/C (PBT-2). The former catalyst was used in batch aerobic oxidation reactions with different primary alcohols and shown to be compatible with substrates bearing heterocycle and halide substituents. The methyl ester products were obtained in >90% yield in nearly all cases. Implementation of the PBT-2 catalyst in a continuous-flow packed-bed reactor achieved nearly 60 000 turnovers with no apparent loss of catalytic activity.
- Mannel, David S.,Ahmed, Maaz S.,Root, Thatcher W.,Stahl, Shannon S.
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supporting information
p. 1690 - 1698
(2017/02/10)
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- Conversion of alcohols to alkyl esters and carboxylic acids using heterogeneous palladium-based catalysts
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Disclosed are methods for synthesizing an ester or a carboxylic acid from an organic alcohol. To form the ester one reacts, in the presence of oxygen gas, the alcohol with methanol or ethanol. This reaction occurs in the presence of a catalyst comprising palladium and a co-catalyst comprising bismuth, tellurium, lead, cerium, titanium, zinc and/or niobium (most preferably at least bismuth and tellurium). Alternatively that catalyst can be used to generate an acid from that alcohol, when water is also added to the reaction mix.
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- Antiurease, antiphosphodiesterase and antiglycation studies of Pd(II) complexes with monodentate hydrazides
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The present study was aimed to synthesize and characterize a series of Pd(II)-benzohydrazide complexes with subsequent high throughput screening to seek their effects as enzyme inhibitors and antiglycating agents. Based on complete characterization via elemental (CHN, Pd) analysis, physical (conductivity, magnetic moment) measurements and spectral (FT-IR, 1H-NMR, 13C-NMR) techniques, all Pd(II) complexes were identified as diamagnetic, neutral and orienting in trans square planar geometry with general formula [PdL2Cl2]. The benzohydrazide (L) in these complexes depicts monodentate behavior, providing terminal amino nitrogen as a donor atom. Compared to inactive precursors (free benzohydrazides and Pd2+), almost all Pd(II) complexes showed in vitro antiglycation activity, illustrating the potential role of resulting complexes in the suppression of diabetes and related disorders. The presence of free carbonyl group in complexes has been recognized as possible cause of antiglycation. This study also indicated Pd(II) compounds as far more superior inhibitors of urease and phosphodiesterase-I than parent ligands; many of them exhibited inhibitions equivalent or even greater than the standard inhibitors (thiourea, urease; EDTA, phosphodiesterase), which shows their potential use in future in the control of peptic ulcer and arthritis, respectively. The structure activity relationship (SAR) study demonstrated that complexation, steric hindrance, position of substituents, electron density around metal centre, hydrogen bonding and coordination mode of complexed ligands play prime role in modulating the biological activities of complexes.
- Qurrat-Ul-Ain,Rasheed, Saima,Mahroof-Tahir, Mohammad,Ashiq, Uzma,Jamal, Rifat Ara,Khurshid, Sumaira,Mustafa, Sana
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p. 864 - 881
(2016/11/21)
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- Design, synthesis and antibacterial activity of isatin derivatives as FtsZ inhibitors
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Seven isatin derivatives have been designed, and their chemical structures were characterized by single crystal X-ray diffraction studies, 1H NMR, MS, and elemental analysis. Structural stabilization followed by intramolecular as well as intermolecular H-bonds makes these molecules as perfect examples in molecular recognition with self-complementary donor and acceptor units within a single molecule. These compounds were evaluated for antimicrobial activities. Docking simulations have been performed to position compounds into the FtsZ active site to determine their probable binding models. All of the compounds exhibited better antibacterial activities. Interestingly, compound 5c and 5d exhibited better antibacterial activities with IC50 values of 0.03 and 0.05 μmol/mL against Staphylococcus aureus, respectively. Compound 5g displays antibacterial activity with IC50 values of 0.672 and 0.830 μmol/mL against Escherichia coli and Pseudomonas aeruginosa, respectively.
- Lian, Zhi-Min,Sun, Juan,Zhu, Hai-Liang
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- Efficient synthesis of amides and esters from alcohols under aerobic ambient conditions catalyzed by a Au/mesoporous Al2O3 nanocatalyst
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An efficient heterogeneous Au/mesoporous alumina nanocatalyst has been successfully developed for the synthesis of amides and esters from simple building blocks of readily available alcohols and amines. The processes were simple and were performed at room temperature and atmospheric pressure of O2 to form the desired products with up to 97% isolated yield. The ability of Au/mesoporous alumina to catalyze these reactions under ambient conditions further enhances the sustainability of these chemical processes. Furthermore, the nanocatalyst was stable to air and water and could be recovered and reused easily. The enhanced catalytic activity of Au/mesoporous alumina might be attributed to the presence of negatively charged Au nanoparticles that could promote oxidation processes as well as the stability of the mesoporous alumina support calcined at a high temperature of 800°C. Gold for green: Gold nanoparticles supported on mesoporous alumina catalyze the efficient synthesis of amides and esters from simple building blocks of readily available alcohols and amines under ambient aerobic reaction conditions (R1=aryl, alkyl, and R2=H, alkyl).
- Chng, Leng Leng,Yang, Jinhua,Ying, Jackie Y.
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p. 1916 - 1925
(2015/06/16)
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- Rhodium-catalyzed C-H activation of hydrazines leads to isoquinolones with tunable aggregation-induced emission properties
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Using an internally oxidizing directing group (DG) strategy, we report a RhIII-catalyzed synthesis of isoquinolones via C-H activation/annulation of benzoylhydrazines and alkynes. Tunable double cascade cyclization of benzoylhydrazines with two equivalents of alkynes led to tetracyclic amides. These N-heterocycles demonstrated adjustable AIE properties.
- Yu, Bole,Chen, Ying,Hong, Mei,Duan, Pingping,Gan, Shifeng,Chao, Hui,Zhao, Zujin,Zhao, Jing
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supporting information
p. 14365 - 14368
(2015/09/21)
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- Synthesis, anti-HIV activity and Molecular modeling study of 3-aryl-6-adamantylmethyl-[1,2,4] triazolo[3,4-b][1,3,4]thiadiazole derivatives
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A series of novel 3-aryl-6-adamantylmethyl-[1,2,4]triazolo[3,4-b][1,3,4]thiadiazoles 6a-l were synthesized by a simple method with the aim of developing novel HIV non-nucleoside reverse transcriptase inhibitors. All the synthesized compounds were structurally confirmed by spectral analyses. The structure of 6a was unambiguously verified by X-ray structure determination. The synthesized compounds were evaluated for their anti-HIV activity and four analogs displayed moderate inhibitory activity with EC50 values ranging from 10.10 to 12.40 μg mL-1. Molecular docking of 6g with HIV-1 reverse transcriptase was studied to rationalize some structureactivity relationships (SARs).
- Khan, Mahmood-Ul-Hassan,Hameed, Shahid,Farman, Muhammad,Al-Masoudia, Najim A.,Stoeckli-Evans, Helen
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p. 609 - 616
(2016/02/18)
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- Silver-mediated fluorination of potassium aryltrifluoroborates with Selectfluor Dedicated to Professor Andrea Vasella on the occasion of his 71st birthday
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A simple and practical procedure for the silver-mediated fluorination of aryl- and heteroaryltrifluoroborates with electrophilic fluorine from Selectfluor and LiOH·H2O is presented. The reaction procedure is simple and easy to set up, the process produces fluorinated arenes and heteroarenes in good to excellent yields and a wide range of electronically and structurally diverse substrates are tolerated.
- Dubbaka, Srinivas Reddy,Narreddula, Venkateswara Reddy,Gadde, Satyanarayana,Mathew, Thresen
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p. 9676 - 9681
(2015/01/08)
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- Copper-catalyzed decarboxylative methylation of aromatic carboxylic acids with PhI(OAc)2
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The copper-catalyzed decarboxylative methylation of aromatic carboxylic acids was developed by using PhI(OAc)2 to provide a new strategy for the methylation of aryl acids through the decarboxylation of alkyl acids. The mechanism and the roles of each reactant in the reaction were investigated extensively. Copyright
- Jiang, Yuyu,Pan, Shulei,Zhang, Yanghui,Yu, Jingxun,Liu, Hongqiang
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supporting information
p. 2027 - 2031
(2014/04/17)
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- Pd-catalyzed nucleophilic fluorination of aryl bromides
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On the basis of mechanism-driven reaction design, a Pd-catalyzed nucleophilic fluorination of aryl bromides and iodides has been developed. The method exhibits a broad substrate scope, especially with respect to nitrogen-containing heteroaryl bromides, and proceeds with minimal formation of the corresponding reduction products. A facilitated ligand modification process was shown to be critical to the success of the reaction.
- Lee, Hong Geun,Milner, Phillip J.,Buchwald, Stephen L.
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supporting information
p. 3792 - 3795
(2014/04/03)
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- Synthesis and evaluation of novel azoles as potent antifungal agents
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Using a rational approach to the design of antifungal agents, a series of azole agents with 1,3,4-oxadiazole side chains were designed and synthesized. The results of preliminary in vitro antifungal tests with eight human pathogenic compounds showed that all of the title compounds exhibited excellent activities against all of the tested fungi except Aspergillus fumigatus. Compounds 11e and 11f were found to be the most effective, with a minimum inhibitory concentration of 0.0039 μg/mL, followed by voriconazole, which has a MIC of 0.0625 μg/mL. The 1,3,4-oxadiazole side chain is not the major contributor but plays a role in eliciting the observed antifungal activity.
- Li, Liangjing,Ding, Hao,Wang, Baogang,Yu, Shichong,Zou, Yan,Chai, Xiaoyun,Wu, Qiuye
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supporting information
p. 192 - 194
(2014/01/17)
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- Transition metal-free oxidative esterification of benzylic alcohols in aqueous medium
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Oxidative esterification of benzylic alcohols with a catalytic amount of HBr-H2O2 in aqueous medium under mild conditions is reported with a wide range of substrate scope for both benzylic and aliphatic alcohols. The conditions are also suitable for selective mono-esterification of ethylene glycol and glycerol. With catalytic amounts of HBr (20 mol%) and H2O2, the generation of reactive intermediate species BrOH has been ascertained by UV-visible spectra.
- Samanta, Supravat,Pappula, Venkatanarayana,Dinda, Milan,Adimurthy, Subbarayappa
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supporting information
p. 9453 - 9456
(2014/12/11)
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- FLUORINATION OF ARYL COMPOUNDS
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The invention provides compositions and methods of using the compositions in fluorinating aryl precursors containing a leaving group replaceable by a fluorine atom. The compositions include a metal ion source, a electrophilic fluorine source, a base, and a compound, which is an aryl precursor of the aryl fluoride, and which has a leaving group replaceable by the fluorine atom. Exemplary methods of the invention make use of such compositions and methods to prepare an aryl fluoride compound. In an exemplary embodiment, the electrophilic fluorine source is a source of 18F.
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-
Paragraph 00117; 00118-00121
(2014/07/22)
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- Synthesis, spectroscopic and radical scavenging studies of palladium(II)-hydrazide complexes
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In present study, a series of palladium(II) complexes with biologically active hydrazide ligands have been synthesized, characterized and screened for their antioxidant (superoxide and DPPH radical scavenging) properties. Spectral studies (FT-IR, EI-mass, 13C and 1H NMR spectroscopy) and physico-chemical measurements including elemental analysis, magnetic susceptibility and conductivity measurements represented square planar structure for all complexes. Substituted and unsubstituted benzohydrazides (1-4) have shown monodentate behavior forming complexes of general formula [PdL 2Cl2]. However, pyridine-carbohydrazides (5 and 6) were coordinated in bidentate fashion of [PdLCl2] general formula producing stable five-membered chelate ring. All palladium complexes were found to be considerably more potent inhibitors of DPPH free radical compared to free hydrazides. These complexes are even stronger DPPH scavengers than standard antioxidant propyl gallate. The complexes have also shown good superoxide scavenging ability compared to inactive free hydrazides, however complexes are weaker superoxide scavengers than ascorbic acid, a standard superoxide inhibitor. An interesting structure activity relationship has been evaluated.
- Ain, Qurrat Ul,Ashiq, Uzma,Jamal, Rifat Ara,Mahrooof-Tahir, Mohammad
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p. 683 - 689
(2013/11/06)
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- Synthesis, antibacterial activities, and 3d-qsar of sulfone derivatives containing 1, 3, 4-oxadiazole moiety
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A series of sulfone derivatives containing 1, 3, 4-oxadiazole moiety were prepared and evaluated for their antibacterial activities by the turbidimeter test. Most compounds inhibited growth of Ralstonia solanacearum (R. solanacearum) from tomato and tobacco bacterial wilt with high potency, among which compounds 5a and 5b exhibited the most potent inhibition against R. solanacearum from tomato and tobacco bacterial wilts with EC50 values of 19.77 and 8.29 μg/mL, respectively. Our results also demonstrated that 5a, 5b, and a number of other compounds were more potent than commercial bactericides Kocide 3000 and Thiodiazole Copper, which inhibited R. solanacearum from tomato bacterial wilt with EC50 values of 93.59 and 99.80 μg/mL and tobacco bacterial wilt with EC50 values of 45.91 and 216.70 μg/mL, respectively. The structure-activity relationship (SAR) of compounds was studied using three-dimensional quantitative structure-activity relationship (3D-QSAR) models created by comparative molecular field analysis (CoMFA) and comparative molecular similarity index analysis (CoMSIA) based on compound bioactivities against tomato and tobacco bacterial wilts. The 3D-QSAR models effectively predicted the correlation between inhibitory activity and steric-electrostatic properties of compounds.
- Li, Pei,Yin, Juan,Xu, Weiming,Wu, Jian,He, Ming,Hu, Deyu,Yang, Song,Song, Baoan
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p. 546 - 556
(2013/11/06)
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- Aerobic oxidation of diverse primary alcohols to methyl esters with a readily accessible heterogeneous Pd/Bi/Te catalyst
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Efficient aerobic oxidative methyl esterification of primary alcohols has been achieved with a heterogeneous catalyst consisting of 1 mol % Pd/charcoal (5 wt %) in combination with bismuth(III) nitrate and tellurium metal. The Bi and Te additives significantly increase the reaction rate, selectivity, and overall product yields. This readily accessible catalyst system exhibits a broad substrate scope and is effective with both activated (benzylic) and unactivated (aliphatic) alcohols bearing diverse functional groups.
- Powell, Adam B.,Stahl, Shannon S.
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supporting information
p. 5072 - 5075
(2013/10/22)
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- Cu-catalyzed fluorination of diaryliodonium salts with KF
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A mild Cu-catalyzed nucleophilic fluorination of unsymmetrical diaryliodonium salts with KF is described. This protocol preferentially fluorinates the smaller aromatic ligand on iodine(III). The reaction exhibits a broad substrate scope and proceeds with high chemoselectivity and functional group tolerance. DFT calculations implicate a CuI/CuIII catalytic cycle.
- Ichiishi, Naoko,Canty, Allan J.,Yates, Brian F.,Sanford, Melanie S.
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supporting information
p. 5134 - 5137
(2013/10/22)
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- Copper-mediated fluorination of arylboronate esters. Identification of a Copper(III) fluoride complex
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A method for the direct conversion of arylboronate esters to aryl fluorides under mild conditions with readily available reagents is reported. Tandem reactions have also been developed for the fluorination of arenes and aryl bromides through arylboronate ester intermediates. Mechanistic studies suggest that this fluorination reaction occurs through facile oxidation of Cu(I) to Cu(III), followed by rate-limiting transmetalation of a bound arylboronate to Cu(III). Fast C-F reductive elimination is proposed to occur from an aryl-copper(III)-fluoride complex. Cu(III) intermediates have been generated independently and identified by NMR spectroscopy and ESI-MS.
- Fier, Patrick S.,Luo, Jingwei,Hartwig, John F.
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supporting information
p. 2552 - 2559
(2013/03/29)
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- Inhibition of tobacco bacterial wilt with sulfone derivatives containing an 1,3,4-oxadiazole moiety
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A series of new sulfone compounds containing the 1,3,4-oxadiazole moiety were designed and synthesized. Their structures were identified by 1H and 13C nuclear magnetic resonance and elemental analyses. Antibacterial bioassays indicated that most compounds exhibited promising in vitro antibacterial bioactivities against tobacco bacterial wilt at 200 μg/mL. The relationship between structure and antibacterial activity was also discussed. Among the title compounds, 5′c, 5′h, 5′i, and 5′j could inhibit mycelia growth of Ralstonia solanacearum in vitro by approximately 50% (EC50) at 39.8, 60.3, 47.9, and 32.1 μg/mL, respectively. Among them, compound 5′j was identified as the most promising candidate due to its stronger effect than that of Kocide 3000 [Cu(OH)2] within the same concentration range. Field trials demonstrated that the control effect of compound 5′j against tobacco bacterial wilt was better than that of the commercial bactericide Saisentong. For the first time, the present work demonstrated that sulfone derivatives containing 1,3,4-oxadiazole can be used to develop potential bactericides for plants.
- Xu, Wei-Ming,Han, Fei-Fei,He, Ming,Hu, De-Yu,He, Jiang,Yang, Song,Song, Bao-An
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scheme or table
p. 1036 - 1041
(2012/06/04)
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- Synthesis, crystal structure and anti-HIV activity of 2-adamantyl/ adamantylmethyl-5-aryl-1,3,4-oxadiazoles
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Two series of 2-adamantyl/adamantylmethyl-5-aryl-1,3,4-oxadiazoles (4a-l and 5a-l) were synthesized by cyclodehydration of adamantan-1-carboxylic acid/adamantylacetic acid with various aryl hydrazides (3a-l) in the presence of POCl3. The synthesis was supported by spectroanalytical techniques and verified further by crystal structure determination of compounds 4e and 5k. The synthesized compounds were screened for their inhibitory activity against HIV-1 and HIV-2 in MT-4 cells. Compound 5b exhibited a moderate activity in vitro for the replication of both virus types, suggesting for further structural modification as a new lead in the development of an antiviral agent.
- Khan, Mahmood-Ul-Hassan,Hameed, Shahid,Akhtar, Tashfeen,Al-Masoudi, Najim A.,Stoeckli-Evans, Helen
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p. 1190 - 1197,8
(2012/12/12)
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- Synthesis, crystal structure and anti-HIV activity of 2-adamantyl/ adamantylmethyl-5-aryl-1,3,4-oxadiazoles
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Two series of 2-adamantyl/adamantylmethyl-5-aryl-1,3,4-oxadiazoles (4a-l and 5a-l) were synthesized by cyclodehydration of adamantan-1-carboxylic acid/adamantylacetic acid with various aryl hydrazides (3a-l) in the presence of POCl3. The synthesis was supported by spectroanalytical techniques and verified further by crystal structure determination of compounds 4e and 5k. The synthesized compounds were screened for their inhibitory activity against HIV-1 and HIV-2 in MT-4 cells. Compound 5b exhibited a moderate activity in vitro for the replication of both virus types, suggesting for further structural modification as a new lead in the development of an antiviral agent.
- Khan, Mahmood-Ul-Hassan,Akhtar, Tashfeen,Al-Masoudi, Najim A.,Stoeckli-Evans, Helen,Hameed, Shahid
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p. 1190 - 1197
(2013/01/15)
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- A general and efficient zinc-catalyzed oxidation of benzyl alcohols to aldehydes and esters
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Go green: A general and efficient zinc-catalyzed oxidation of benzyl alcohols has been developed. In the presence of a zinc catalyst, various aldehydes and esters have been prepared in good to excellent yields under mild conditions (see scheme).
- Wu, Xiao-Feng
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experimental part
p. 8912 - 8915
(2012/09/22)
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- Metal-Catalyzed Carbon-Fluorine Bond Formation
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One aspect of the invention relates to a metal-catalyzed conversion of aryl halides and sulfonates to the corresponding aryl fluorides. Another aspect of the invention relates to a metal-catalyzed conversion of heteroaryl halides and sulfonates to the corresponding heteroaryl fluorides. Another aspect of the invention relates to a metal-catalyzed conversion of vinyl halides and sulfonates to the corresponding vinyl fluorides. In certain embodiments, simple fluoride sources, such as AgF and CsF, are used. In certain embodiments, the transformations tolerate a wide range of functional groups, allowing for introduction of fluorine atoms into highly functionalized organic molecules.
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Page/Page column 18
(2011/02/18)
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- FUSED HETEROCYCLIC COMPOUNDS AS OREXIN RECEPTOR MODULATORS
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Certain disubstituted 3,8-diaza-bicyclo[4.2.0]octane and 3,6-diazabicyclo [3.2.0]heptane are described, which are useful as orexin inhibitors. Such compounds may be useful in pharmaceutical compositions and methods for the treatment of diseased states, disorders, and conditions mediated by orexin activity, such as insomnia.
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Page/Page column 77-78
(2011/05/06)
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- Synthesis, crystal structure and antiproliferative activity of 6-adamantyl-3-aryl[1,2,4]triazolo[3,4-b][1,3,4]thiadiazoles
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A series of 3,6-disubstituted [1,2,4]triazolo[3,4-b][1,3,4]thiadiazoles 5a - l bearing an adamantyl moiety were synthesized by condensation of 4-amino-5-aryl-2H-1,2,4-triazole-3(4H)-thiones 4a - l with adamantyl-1- carboxylic acid in the presence of POCl3. The structures of the newly synthesized compounds were established using spectroanalytical techniques and verified further by the crystal structure determination of compounds 5a and 5j. The compounds were screened for their antiproliferative activity against a large panel of human cell lines.
- Khan, Mahmood-Ul-Hassan,Akhtar, Tashfeen,Yasin, Khawaja A.,Al-Masoudi, Najim A.,Jones, Peter G.,Hameed, Shahid
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scheme or table
p. 178 - 184
(2010/08/22)
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- Design, synthesis, and urease inhibition studies of a series of 4-amino-5-aryl-3H-1,2,4-triazole-3-thiones
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A series of 4-amino-5-aryl-3H-1,2,4-triazole-3-thiones was synthesized by reaction of aryl hydrazides with CS2 and hydrazine hydrate. The synthesized compounds were characterized by spectroanalytical techniques, and their urease inhibition activity was evaluated using jack bean urease. All but one of the synthesized compounds were active, and two of them were found to be more potent than the standard, with 50% inhibition concentration (IC 50) values of 17.5 ± 0.52 and 4.3 ± 0.169 μM, respectively (standard IC 50 = 21.0 ± 0.11 μM). Tentative statements regarding the role of different functional groups in binding to the enzyme active site are also presented.
- Khan, Mahmood-Ul-Hassan,Hameed, Shahid,Yasin, Khawaja A.,Akhtar, Tashfeen,Khan, Khalid M.
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scheme or table
p. 479 - 484
(2011/08/03)
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- Lithium bromide as a flexible, mild, and recyclable reagent for solvent-free cannizzaro, tishchenko, and meerwein-ponndorf-verley reactions
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A room temperature convenient disproportionation or reduction of aldehydes prompted by lithium bromide and triethylamine is described in a solvent-free environment. Distribution of the products to selectively direct the process toward Cannizzaro or Tishchenko reactions is controlled by the type of workup selection. The presence of hydrogen donor alcohols in the mixture completely diverts the process toward the MeerweinPonndorf-Verley reaction.
- Mojtahedi, Mohammad M.,Akbarzadeh, Elahe,Sharifi, Roholah,Abaee, M. Saeed
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p. 2791 - 2793
(2008/02/05)
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- A novel direct conversion of primary amides to their corresponding methyl esters
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A novel method was used to directly convert aliphatic and aromatic primary amides into their corresponding methyl esters in high yields (up to 99 %) under mild reaction conditions. Possible mechanisms were studied at the B3LYP/6-31++G(d,p) level of theory. Formation of the ester proceeded through a rearrangement of the -OMe and -NH2 groups in the RC(O)NHS(O)OMe intermediate in a H+-catalyzed six-membered ring transition state structure. Wiley-VCH Verlag GmbH & Co. KGaA, 2007.
- Li, Ang-Chun,Ren, Jie,Liao, Tou-Gen,Jiang, Ju-Xing,Zhu, Hua-Jie
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p. 1026 - 1030
(2008/03/12)
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- Oxime amides and hydrazone amides having fungicidal activity
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The invention relates to compounds having usefulness in the control of Take-All disease in plants, particularly cereals, a method for the control of Take-All disease, and fungicidal compositions for carrying out the method. Compounds of the invention are oximes or hydrazones of arylgloxamides or heteroarylglyoxamides or cycloalkenylglyoxamides.
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Page column 12-13
(2008/06/13)
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- Dependence of intramolecular dissociative electron transfer rates on driving force in Donor-Spacer-Acceptor systems
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The voltammetric reduction of a series of phenyl-substituted 4- benzoyloxy-1-methylcyclohexyl bromides has been investigated in DMF. The reduction leads to the cleavage of the C-Br bond. On a thermodynamic ground, the direct reduction of the tertiary C-Br function is easier than that of the selected benzoates by at least 0.5 V. However, since the direct reduction of bromides is affected by a large activation overpotential, the electron is first located in the benzoate moiety. The rate constant for the following exergonic intramolecular dissociative electron transfer was determined by kinetic analysis of the cyclic voltammetry curves. The intermolecular rate constants for the reaction between the radical anions of methyl benzoates and 4-tert-butyl-1-methylcyclohexyl bromide were also determined and found to correlate very well with related literature data pertaining to tert-butyl bromide. The intramolecular rate constants were found to be more sensitive to variation of driving force than the corresponding intermolecular data. This result can be attributed to a shift of the center of the π* orbital of the radical anion donor away from the acceptor moiety, the shift being larger for the most easily reduced donors. The resulting distance increase is therefore envisaged as responsible for a more rapid rate drop, compared to the intermolecular pattern, when smaller driving forces are considered.
- Antonello, Sabrina,Maran, Flavio
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p. 5713 - 5722
(2007/10/03)
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- A New Indirect Application of Aggregative Activation: Synthesis of Esters by Cobalt-Catalyzed Carbonylation of Aryl, Heterocyclic, and Vinyl Halides under Atmospheric Pressure
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Sun lamp illuminated alkoxycarbonylation of aryl, heteroaryl, and vinyl halides was performed under atmospheric pressure of CO in the presence of a cobalt catalyst in situ generated from Co(OAc)2.Illunination through a Pyrex flask was sufficient to catalyze the reaction.This process avoids the use of Co2(CO)8 and excess CH3I, which were required in the earlier procedure.A SRN1 mechanism is proposed.
- Marchal, Joel,Bodiguel, Jacques,Fort, Yves,Caubere, Paul
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p. 8336 - 8340
(2007/10/02)
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- Process for the preparation of alkyl fluorobenzoates in high purity and high yield
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Process for the preparation of alcohol fluorobenzoates of the formula (I) STR1 in which R is an alkyl radical and Fn is 1 to 4 fluorine atoms which, independently of one another, are bonded to the aromatic ring, by reacting a fluorobenzyl chloride of the formula (II) STR2 in which Fn is as defined above, with an at least stoichiometric amount of an alkali metal alcoholate ROM in which R is as defined above and M is an alkali metal from the group consisting of Li, Na and K, in the corresponding alcohol ROH at temperatures from -10° C. to 150° C., the solvent is distilled off, if appropriate, and the alkali metal chloride formed is separated off by treating the mixture with water or by filtration.
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-
- Correlation of Carbon-13 Substituent-Induced Chemical Shifts: meta- and para-Substituted Methyl Benzoates
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Carbon-13 NMR spectra are reported for 69 substituted methyl benzoates in deuteriochloroform or in its mixture with dimethyl sulphoxide-d6.The substituent-induced chemical shifts (SCS) of the CO carbon correlate poorly with dual substituent parameters (DSP) in all possible modifications, and for meta derivatives in particular this correlation is both overparameterized and imprecise.A much better correlation was obtained with parameters (designated Bm, Bp and Cp) derived previously by principal component analysis (PCA) from a larger set.The SCS of the CH3 carbon correlate very well with the original simple Hammett equation, and no DSP treatment is needed.The clustering of substituents is not consequential in such a large set.KEY WORDS Methyl benzoates 13C NMR Substituent effects
- Budesinsky, Milos,Exner, Otto
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p. 585 - 591
(2007/10/02)
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