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The discovery of novel small molecule allosteric activators of aldehyde dehydrogenase 2
Aldehyde dehydrogenase 2 (ALDH2) plays important role in ethanol metabolism, and also serves as an important shield from the damage occurring under oxidative stress. A special inactive variant was found carried by 35–45% of East Asians. The variant carriers have recently been found at the higher risk for the diseases related to the damage occurring under oxidative stress, such as cardiovascular and cerebrovascular diseases. As a result, ALDH2 activators may potentially serve as a new class of therapeutics. Herein, N-benzylanilines were found as novel allosteric activators of ALDH2 by computational virtual screening using ligand-based and structure-based screening parallel screening strategy. Then a structural optimization was performed and has led to the discovery of the compound C6. It has good activity in vitro and in vivo, which could reduce infarct size by ～70% in ischemic stroke rat models. This study provided good lead compounds for the further development of ALDH2 activators.
Tian, Wei,Guo, Jiapeng,Zhang, Qingsen,Fang, Shaoyu,Zhou, Ruolan,Hu, Jian,Wang, Mingping,Zhang, Yuefan,Guo, Jin-Min,Chen, Zhuo,Zhu, Ju,Zheng, Canhui
(2020/12/30)

Design, synthesis, in vitro and in vivo evaluation against MRSA and molecular docking studies of novel pleuromutilin derivatives bearing 1, 3, 4-oxadiazole linker
A class of pleuromutilin derivatives containing 1, 3, 4-oxadiazole were designed and synthesized as potential antibacterial agents against Methicillin-resistant staphylococcus aureus (MRSA). The ultrasound-assisted reaction was proposed as a green chemistry method to synthesize 1, 3, 4-oxadiazole derivatives (intermediates 85–110). Among these pleuromutilin derivatives, compound 133 was found to be the strongest antibacterial derivative against MRSA (MIC = 0.125 μg/mL). Furthermore, the result of the time-kill curves displayed that compound 133 could inhibit the growth of MRSA in vitro quickly (- 4.36 log10 CFU/mL reduction). Then, compound 133 (- 1.82 log10 CFU/mL) displayed superior in vivo antibacterial efficacy than tiamulin (- 0.82 log10 CFU/mL) in reducing MRSA load in mice thigh model. Besides, compound 133 exhibited low cytotoxicity to RAW 264.7 cells. Molecular docking studies revealed that compound 133 was successfully localized in the binding pocket of 50S ribosomal subunit (ΔGb = -10.50 kcal/mol). The results indicated that these pleuromutilin derivatives containing 1, 3, 4-oxadiazole might be further developed into novel antibiotics against MRSA.
Liu, Jie,Zhang, Guang-Yu,Zhang, Zhe,Li, Bo,Chai, Fei,Wang, Qi,Zhou, Zi-Dan,Xu, Ling-Ling,Wang, Shou-Kai,Jin, Zhen,Tang, You-Zhi
(2021/05/17)

Nitration of deactivated aromatic compounds via mechanochemical reaction
A variety of deactivated arenes were nitrated to their corresponding nitro derivatives in excellent yields under high-speed ball milling condition using Fe(NO3)3·9H2O/P2O5 as nitrating reagent. A radical involved mechanism was proposed for this facial, eco-friendly, safe, and effective nitration reaction.
Wu, Jian-Wei,Zhang, Pu,Guo, Zhi-Xin
supporting information

(2021/05/05)

Pleuromutilin derivative with 1, 3, 4-oxadiazole side chain and preparation and application thereof
The invention belongs to the field of medicinal chemistry, and particularly relates to a pleuromutilin derivative with a 1, 3, 4-oxadiazole side chain and preparation and application thereof The pleuromutilin derivative with the 1, 3, 4-oxadiazole side chain is a compound shown in a formula 2 or a pharmaceutically acceptable salt thereof, and a solvent compound, an enantiomer, a diastereoisomer and a tautomer of the compound shown in the formula 2 or the pharmaceutically acceptable salt thereof or a mixture of the solvent compound, the enantiomer, the diastereoisomer and the tautomer in any proportion, including a racemic mixture. The pleuromutilin derivative has good antibacterial activity, is especially suitable for being used as a novel antibacterial agent for systemic system infection of animals or human beings, and has good water solubility.
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Paragraph 0055-0056; 0070; 0090; 0092; 0095; 0103

(2021/07/24)

Vitamin B1-catalyzed aerobic oxidative esterification of aromatic aldehydes with alcohols
A straightforward aerobic oxidative esterification of aryl aldehydes with alcohols has been developed for the synthesis of substituted esters by employing vitamin B1 as a cost-effective, metal-free, and eco-friendly NHC catalyst. Air is used as a green terminal oxidant. The reaction is a useful addition to the existing NHC-catalytic oxidative esterification.
Chu, Xue-Qiang,Ge, Danhua,Luo, Xin-Long,Xu, Pei,Yu, Zi-Lun
supporting information
p. 30937 - 30942
(2021/11/19)

Selective and Additive-Free Hydrogenation of Nitroarenes Mediated by a DMSO-Tagged Molecular Cobalt Corrole Catalyst
We report on the first cobalt corrole that effectively mediates the homogeneous hydrogenation of structurally diverse nitroarenes to afford the corresponding amines. The given catalyst is easily assembled prior to use from 4-tert-butylbenzaldehyde and pyrrole followed by metalation of the resulting corrole macrocycle with cobalt(II) acetate. The thus-prepared complex is self-contained in that the hydrogenation protocol is free from the requirement for adding any auxiliary reagent to elicit the catalytic activity of the applied metal complex. Moreover, a containment system is not required for the assembly of the hydrogenation reaction set-up as both the autoclave and the reaction vessels are readily charged under a regular laboratory atmosphere.
Sch?fberger, Wolfgang,Timelthaler, Daniel,Topf, Christoph
supporting information
p. 2114 - 2120
(2021/07/22)

Design, Synthesis, and Study of the Insecticidal Activity of Novel Steroidal 1,3,4-Oxadiazoles
A series of novel steroidal derivatives with a substituted 1,3,4-oxadiazole structure was designed and synthesized, and the target compounds were evaluated for their insecticidal activity against five aphid species. Most of the tested compounds exhibited potent insecticidal activity against Eriosoma lanigerum (Hausmann), Myzus persicae, and Aphis citricola. Compounds 20g and 24g displayed the highest activity against E. lanigerum, showing LC50 values of 27.6 and 30.4 μg/mL, respectively. Ultrastructural changes in the midgut cells of E. lanigerum were detected by transmission electron microscopy, indicating that these steroidal oxazole derivatives might exert their insecticidal activity by destroying the mitochondria and nuclear membranes in insect midgut cells. Furthermore, a field trial showed that compound 20g exhibited effects similar to those of the positive controls chlorpyrifos and thiamethoxam against E. lanigerum, reaching a control rate of 89.5% at a dose of 200 μg/mL after 21 days. We also investigated the hydrolysis and metabolism of the target compounds in E. lanigerum by assaying the activities of three insecticide-detoxifying enzymes. Compound 20g at 50 μg/mL exhibited inhibitory action on carboxylesterase similar to the known inhibitor triphenyl phosphate. The above results demonstrate the potential of these steroidal oxazole derivatives to be developed as novel pesticides.
Bai, Hangyu,Jiang, Weiqi,Li, Qi,Li, Tian,Ma, Shichuang,Shi, Baojun,Wu, Wenjun
p. 11572 - 11581
(2021/10/12)

Green synthesis of zinc oxide particles with apple-derived compounds and their application as catalysts in the transesterification of methyl benzoates
ZnO nanoparticles (ZnONPs) were successfully synthesized using bravo-de-esmolfe apple extract in aqueous medium at room temperature. ZnO microparticles, prepared with a pure apple phytochemical, quercetin (ZnOq), or without phytochemicals (ZnO) were studied for comparative purposes. The re-use of apple waste for highly efficient catalyst production, based on green synthetic routes, can be added to the concept of a circular economy. The synthesized ZnO particles were characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM), and N2adsorption/desorption Brunauer-Emmett-Teller (BET) theory. The XRD patterns indicated the formation of a hexagonal wurtzite phase with high purity and SEM and TEM analyses revealed the morphology of the particles. The apple extract produced spherical ZnONPs composed of round lamina-like structures, similar to the micro sized lamina-like shape of ZnOq and dissimilar to the flower-like shape of ZnO. The green synthesized ZnO nanoparticles (ZnONPs) led to a high product yield ofca. 96% within 24 h of reaction time in the transesterification reaction of different carboxylic esters.
Alegria, Elisabete C. B. A.,Alves, Marta M.,Fátima Montemor, M.,Pombeiro, Armando J. L.,Ribeiro, Ana P. C.,Saraiva, Marta S.,Soliman, Mohamed M. A.
p. 6488 - 6494
(2020/06/03)

Oxidative Esterification of Aldehydes and Alcohols Catalyzed by Camphor-Based Imidazolium Salts
Abstract: Sixteen new camphor-based imidazolium salts have been synthesized with renewable camphorsulfonic acid as the starting material. The chemical shifts of the characteristic proton of C2 on the imidazolium ring (N?C=N) were discussed thoroughly and all of these imidazolium salts exhibit good thermal stability. Furthermore, the excellent catalytic performance of the synthesized imidazolium salts were observed in the oxidative esterification between aromatic or aliphatic aldehydes containing electron-withdrawing or electron-donating groups on aromatic ring and primary or secondary alcohol by air as the sole oxidant. Graphic Abstract: [Figure not available: see fulltext.].
Bian, Tiancen,Feng, Li,Li, Danfeng,Huang, Jiaxin,Zhao, Yuxun,Xu, Xu,Yang, Yiqin,Wang, Shifa
p. 1812 - 1820
(2020/01/11)

METHOD FOR THE SYNTHESIS AND PURIFICATION OF ARYL ACID ESTERS
The general inventive concepts are directed to the discovery that certain aryl acids can be esterified under particular conditions to provide the resulting ester as a solid that precipitates in good yield from the reaction mixture. The esters may then be isolated and purified with relative ease. Accordingly, a method for the esterification, isolation, and purification of aryl acids is provided.
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Paragraph 0029-0030

(2019/10/17)

Copper-catalyzed demethylative esterification of arylmethylketones: a new route for the synthesis of benzocaine
An efficient method for oxidative cleavage of C(CO)–C bonds of ketones has been developed. This procedure enables activated methyl ketones to react with tetraethyl orthosilicate for generation of the corresponding methyl esters using copper as the catalyst. Primary mechanistic studies revealed that in contrary to other related studies, the involvement of the aldehyde as the intermediate of this reaction is highly probable. Interestingly, this study provides an unprecedented positive effect of the elemental sulfur upon this oxidative esterification reaction. As an application of our method, we have reported a two-step procedure for the synthesis of benzocaine. The second step of this procedure involves a highly selective reduction in nitro group in the presence of ester functionality.
Roodan, Sajedeh Maddah,Ghaderi, Arash
p. 2327 - 2332
(2019/06/27)

Metal-free aerobic oxidative esterification of aromatic aldehydes promoted by potassium fluoride (KF)
We investigated the oxidative esterification of aldehydes with alcohols/phenols to produce a range of esters. In this approach, we conducted the reaction under metal-free conditions at room temperature. The reactions were promoted by potassium fluoride (KF) as the additive, resulting in the desired product in good to high yields. This procedure was found to be effective for the production of aryl esters, which are challenging in most of the available reports. It is vital for this procedure not to exclude air as the source of oxygen.
Soltani, Roghaye,Ghaderi, Arash
p. 1572 - 1576
(2019/06/24)

Camphoryl imidazole type ionic liquid and preparation method and application thereof
The invention discloses a camphoryl imidazole type ionic liquid and a preparation method and application thereof. According to the preparation method, a derivative camphorsulfonic acid of a natural renewable resource camphor is taken as a raw material to prepare 10-iodocamphor; then the 10-iodocamphor and aryl imidazole are subjected to a quaterisation reaction to prepare camphoryl imidazole iodide; then the camphoryl imidazole iodide and sodium hexafluorophosphate, sodium tetrafluoroborate, bis(trifluorosulfonimide)lithium and the like are subjected to ion exchange to prepare camphoryl imidazole hexafluorophosphate, camphoryl imidazole tetrafluoroborate, camphoryl imidazole bis(trifluorosulfonimide)salt and other ionic liquids. The camphoryl imidazole type ionic liquid shows good catalytic activity for an oxidation esterification reaction of aldehyde-alcohol, has the advantages of short reaction time, good reaction selectivity and high product yield, and has a good application prospect.
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Paragraph 0060; 0062

(2019/10/05)

Improving the Potency of Cancer Immunotherapy by Dual Targeting of IDO1 and DNA
Herein we report the first exploration of a dual-targeting drug design strategy to improve the efficacy of small-molecule cancer immunotherapy. New hybrids of indoleamine 2,3-dioxygenase 1 (IDO1) inhibitors and DNA alkylating nitrogen mustards that respectively target IDO1 and DNA were rationally designed. As the first-in-class examples of such molecules, they were found to exhibit significantly enhanced anticancer activity in vitro and in vivo with low toxicity. This proof-of-concept study has established a critical step toward the development of a novel and effective immunotherapy for the treatment of cancers.
Fang, Kun,Dong, Guoqiang,Wang, Hongyu,He, Shipeng,Wu, Shanchao,Wang, Wei,Sheng, Chunquan
supporting information
p. 30 - 36
(2017/12/26)

N-(5-Methyl-1,3-Thiazol-2-yl)-2-{[5-((Un)Substituted- Phenyl)1,3,4-Oxadiazol-2-yl]Sulfanyl}acetamides. Unique Biheterocycles as Promising Therapeutic Agents
An electrophile, 2-bromo-N-(5-methyl-1,3-thiazol-2-yl)acetamide, was synthesized by the reaction of 5-methyl-1,3-thiazol-2-amine and bromoacetyl bromide in an aqueous medium. In a parallel scheme, a series of (un)substituted benzoic acids was converted sequentially into respective esters, acid hydrazides, and then into 1,3,4-oxadiazole heterocyclic cores. The electrophile was coupled with the aforementioned 1,3,4-oxadiazoles to obtain the targeted bi-heterocyles. Structural analysis of the synthesized compounds was performed by IR, EI-MS, 1H NMR, and 13C NMR. The enzyme inhibition study of these molecules was carried out against four enzymes, namely, acetylcholinesterase, butyrylcholinesterase, α-glucosidase, and urease. The interactions of these compounds with respective enzymes were recognized by their in silico study. Moreover, their cytotoxicity was also determined to find out their utility as possible therapeutic agents.
Abbasi,Ramzan,Aziz-ur-Rehman,Siddiqui,Shah,Hassan,Seo,Ashraf,Mirza,Ismail
p. 801 - 811
(2019/02/27)

Formation of esters and amides via metal-free Csp2-Csp3 bond cleavage of α-nitro ketone: Mechanistic insight to the reaction pathway
A catalyst free protocol for hucleophilic Csp2-Csp3 bond cleavage of a-nitroketone has been achieved for the formation of C-O and C-N bond. A series of differently substituted a-nitroketones could be selectively cleaved and converted into corresponding esters and tosylamides in presence of alcohols and bromamine-T respectively. Mechanism of the C-C bond cleavage has been proposed by identifying different reaction intermediates using IR and NMR spectroscopic methods.
Sarma, Manas Jyoti,Phukan, Prodeep
p. 523 - 533
(2019/05/21)

Unprecedented alkylation of carboxylic acids by boron trifluoride etherate
The alkylation of carboxylic acids by an ethyl moiety of boron trifluoride etherate in the absence of ethyl alcohol from the reaction system is unexpected and novel. Both aromatic and aliphatic carboxylic acids were clearly alkylated affording good yields in short reaction times with the exception of nicotinic acid that necessitated an overnight reaction. It was noted that while ortho-substituted hydroxyl groups of carboxylic acids investigated were not affected by alkylation, those of meta- and para-substituted carboxylic acids were partially etherified. Furthermore, the alkylation reaction was found to be compatible with a range of functional groups such as halogens, amino and nitro groups except for the alkene function of undecylenic acid that underwent polymerisation with concomitant alkylation of its carboxylic acid function.
Jumbam, Ndze D.,Maganga, Yamkela,Masamba, Wayiza,Mbunye, Nomthandazo I.,Mgoqi, Esethu,Mtwa, Sphumusa
p. 387 - 392
(2018/09/06)

7-substituted-4-aryl coumarins compound, and preparation method and application thereof
The invention discloses a 7-substituted-4-aryl coumarins compound, and a preparation method and an application thereof and belongs to the technical field of antitumor drugs. The 7-substituted-4-aryl coumarins compound is acquired in the manner of modifying and remolding 4 and 7 loci of the coumarins. The structural formula is shown in the specification. A pharmacological experiment proves that such a compound has an excellent antitumor activity, can be used for preparing the antitumor drugs, is capable of supplying a new selection for the development and application of the antitumor drugs and further can be applied to the design and optimization of the antitumor drugs. The preparation method of the compound has the advantages of easily acquired raw materials, mild reaction condition, easily realized synthesis method, simple reaction process and operation, low-cost reagents and higher yield.
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Paragraph 0059; 0060

(2017/08/02)

Design and optimization of N-acylhydrazone pyrimidine derivatives as E. coli PDHc E1 inhibitors: Structure-activity relationship analysis, biological evaluation and molecular docking study
By targeting the thiamin diphosphate (ThDP) binding site of Escherichia coli (E. coli) pyruvate dehydrogenase multienzyme complex E1 (PDHc E1), a series of novel ‘open-chain’ classes of ThDP analogs A, B, and C with N-acylhydrazone moieties was designed and synthesized to explore their activities against E. coli PHDc E1 in vitro and their inhibitory activity against microbial diseases were further evaluated in vivo. As a result, A1–23 exhibited moderate to potent inhibitory activities against E. coli PDHc E1 (IC50 = 0.15–23.55 μM). The potent inhibitors A13, A14, A15, C2, had strong inhibitory activities with IC50 values of 0.60, 0.15, 0.39 and 0.34 μM against E. coli PDHc E1 and with good enzyme-selective inhibition between microorganisms and mammals. Especially, the most powerful inhibitor A14 could 99.37% control Xanthimonas oryzae pv. Oryzae. Furthermore, the binding features of compound A14 within E. coli PDHc E1 were investigated to provide useful insights for the further construction of new inhibitor by molecular docking, site-directed mutagenesis, and enzymatic assays. The results indicated that A14 had most powerful inhibition against E. coli PDHc E1 due to the establishment of stronger interaction with Glu571, Met194, Glu522, Leu264 and Phe602 at active site of E.coli PDHc E1. It could be used as a lead compound for further optimization, and may have potential as a new microbicide.
He, Haifeng,Xia, Hongying,Xia, Qin,Ren, Yanliang,He, Hongwu
p. 5652 - 5661
(2017/10/09)

Synthesis, spectral analysis and antibacterial evaluation of 5-substituted-1,3,4-oxadiazol-2-yl 4-(4-methylpiperidin-1-ylsulfonyl)benzyl sulfides
Owing to valuable biological activities of 1,3,4-oxadiazole, sulfamoyl and piperidine functionalities, some new 1-(4-{[(5-substituted-1,3,4-oxadiazol-2-yl) thio]methyl}benzene sulfonyl)-4-methylpiperidine (6a-o) derivatives have been introduced. The target molecules were synthesized from different aralkyl/aryl carboxylic acids, 1a-o, through a series of steps. First the compounds, 1a-o, were converted to heterocyclic 1,3,4-oxadiazole nucleophiles, 4a-o. Second an electrophile as 1-(4-bromomethylbenzenesulfonyl)-4-methylpiperidine (5) was synthesized from 4-methylpiperidine. Finally the target compounds, 6a-o, were prepared by reacting 4a-o with 5 in DMF and LiH. The final compounds were structurally elucidated by spectral data of IR, 1H-NMR and EI-MS. All the compounds were screened for their antibacterial evaluation and found to exhibit valuable results.
Aziz-Ur-Rehman,Ahtzaz, Samreen,Abbasi, Muhammad Athar,Siddiqui, Sabahat Zahra,Rasool, Shahid,Ahmad, Irshad
p. 3370 - 3375
(2017/05/22)

Synthesis and pharmacological screening: Sulfa derivatives of 2-pipecoline-bearing 1,3,4-oxadiazole core
An electrophile, 1-(4-(bromomethylbenzenesulfonyl)-2-methylpiperidine, was synthesized by the reaction of 2-methylpiperidine (2-pipecoline) and 4-bromomethylbenzenesulfonyl chloride in a weak basic medium under pH control. A series of nucleophiles, 5-aryl/aralkyl-1,3,4-oxadiazol-2-thiols, were synthesized from corresponding carboxylic acids in three steps. The title molecules were synthesized by coupling the electrophile to nucleophiles in an aprotic medium using LiH as an activator. The structures of all synthesized compounds were corroborated through IR, 1H NMR, and EI-MS techniques. All the compounds were screened for their pharmacological behavior, particularly, antibacterial and enzyme inhibitory activities. Notably efficient results were obtained against both gram-positive and gram-negative bacterial strains. Regarding enzyme inhibition, compounds were efficient against acetylcholinesterase and butyrylcholinesterase.
Aziz-ur-Rehman,Arif,Abbasi,Siddiqui,Rasool,Shah
p. 328 - 339
(2017/07/04)

Synthesis and anti-inflammatory activity of hydrazide-hydrazones bearing anacardic acid and 1,2,3-triazole ring based hybrids
A novel series of hydrazide-hydrazone derivatives 39-50, linked with anacardic acid motif and 1,2,3-triazole ring were synthesized by reacting 4-(1-(2-methoxy-6-pentadecylbenzyl)-1H-1, 2, 3-triazol-4-yl)benzaldehyde with 2-phenyl-acetohydrazides and benzohydrazides. The structures of the newly synthesized hydrazide-hydrazone derivatives 39-50 were confirmed by 1H NMR, MS and IR spectroscopic tools. These compounds were also evaluated for their anti-inflammatory activity by carrageenan paw edema method.
Kumar Reddy,Kathale, Niren E
p. 2930 - 2936
(2018/02/20)

Zinc Complexes with Cyanoxime: Structural, Spectroscopic, and Catalysis Studies in the Pivaloylcyanoxime-Zn System
Reaction of 2-hydroxyimino-4,4-dimethyl-3-oxo-pentanenitrile (common abbreviation HPiCO, pivaloyl-cyanoxime) with zinc sulfate in an aqueous solution results in the formation of the two new complexes: [Zn(PiCO){H(PiCO)2}(H2O)] (I) and tetranuclear Zn complex [Zn4(μ3-OH)2(PiCO)6 (H2O)4] (II). Both complexes were characterized by elemental analysis, IR- and UV-visible spectra, DSC/TGA studies, and X-ray analysis. In complex II, the PiCO- cyanoxime anion adopts three bidentate binding modes: O-monodentate, chelating (κ2), and bridging (2) coordinations. Also, the ligand represents the mixture of two diasteromers (cis-anti and cis-syn) that form five- and six-membered chelate rings with Zn atoms and cocrystallize in one unit cell at population of 0.57-0.43. There are two crystallographically different Zn-centers in the ASU, and two μ3-bridging hydroxo-groups arrange via inversion center the formation of an elegant tetranuclear complex. Each Zn atom has a molecule of coordinated water and is in the distorted octahedral environment. Because of the structural flexibility and multidentate propensity of the pivaloyl-cyanoxime, complex II may act as a structural model of naturally occurring Zn-containing enzymes. Indeed, compound I exhibits an efficient catalytic performance for transesterification reaction of various esters in ethanol under mild reaction conditions. Therefore, obtained results allow assignment of observed activity as green catalysis.
Opalade, Adedamola A.,Karmakar, Anirban,Rúbio,Pombeiro, Armando J. L.,Gerasimchuk, Nikolay
p. 13962 - 13974
(2017/11/24)

Solvent- and Metal-free Oxidative Esterification of Aromatic Aldehydes Using Urea-2,2-dihydroperoxypropane as a New Solid Oxidant
Urea-2,2-dihydroperoxypropane as a noble and solid gem-dihydroperoxide derivative was used to transform various aromatic aldehydes to their corresponding benzoate derivatives in the presence of HBr under mild conditions at room temperature in high yields and short reaction times.
Khosravi, Kaveh,Khalaji, Kobra,Naserifar, Shirin
p. 303 - 309
(2017/03/27)

Facile Coupling of Aldehydes with Alcohols: An Evolved Tishchenko Process for the Preparation of Unsymmetrical Esters
A facile coupling process between aldehydes and alcohols to afford unsymmetrical esters is presented herein. This transformation is complementary to the Tishchenko reaction and provides access to unsymmetrical esters under very mild conditions. Various aldehydes and alcohols are suitable in this reaction, and the addition of a sacrificial trifluoromethyl ketone allows the process to take place in a highly selective manner. A plausible mechanism based on details obtained by monitoring the reaction progress and deuterium-labeling studies has been proposed.
Liu, Heng,Eisen, Moris S.
p. 4852 - 4858
(2017/09/07)

Selective Actinide-Catalyzed Tandem Proton-Transfer Esterification of Aldehydes with Alcohols for the Production of Asymmetric Esters
Actinide-catalyzed tandem proton-transfer esterification between aldehydes and alcohols is presented herein for the first time. It represents a novel convenient and external-oxidant-free methodology in the preparation of asymmetric ester compounds. Various kinds of aldehydes and alcohols can be applied to this reaction, affording the corresponding ester product in moderate to high yields. A plausible mechanism was proposed on the basis of the kinetic, stoichiometric, and deuterium-labeling studies.
Liu, Heng,Eisen, Moris S.
supporting information
p. 1461 - 1464
(2017/04/28)

Synthesis of novel benzohydrazides bearing 4-[3-methyl-4-(methylsulfonyl)pyridin-2-yl] moiety as potential antibacterial agents
This work reports the synthesis and antibacterial activity of novel hydrazone derivatives 8a-k bearing 4-[3-methyl-4-(methylsulfonyl)pyridin- 2-yl] moiety. Spectroscopic techniques like 1H NMR, mass and IR tools was utilized for the characterization of these hydrazone derivatives. The synthesized hydrazone derivatives were tested against a set of bacterial strains, namely, Escherichia coli, Pseudomonas aeruginosa, Staphylococcus aureus and Streptococcus pyogenes by paper disc diffusion method. Compounds 8b, 8d, 8e, 8f, 8h, 8i showed good antibacterial activity against the test organisms.
Saidugari, Swamy,Rao, V. Lakshmana,Vidya,Ram,Balram
p. 639 - 643
(2016/01/20)

Combretastatin linked 1,3,4-oxadiazole conjugates as a Potent Tubulin Polymerization inhibitors
A new class of combretastatin linked 1,3,4-oxadiazoles were designed, synthesized and screened for their cytotoxic activity against five human cancer cell lines such as HeLa, DU-145, A549, MDA-MB-231 and B16. These compounds showed significant cytotoxicity with IC50 values in the range 0.118-54.32 μM. Conjugate 5m displayed potent antiproliferative activity against DU-145 cell line. Flow cytometric analysis revealed that these compounds arrested the cell cycle in G2/M phase. Moreover, the tubulin polymerization assay and immunofluorescence analysis indicate that 5m exhibits potent inhibitory effect on the tubulin assembly. Further, DNA fragmentation and Hoecst staining assays confirm that 5m induces apoptosis. Molecular docking studies and competitive binding assay indicated that 5m effectively bind at the colchicine binding site of the tubulin.
Kamal, Ahmed,Srikanth,Vishnuvardhan,Kumar, G. Bharath,Suresh Babu, Korrapati,Hussaini, S.M. Ali,Kapure, Jeevak Sopanrao,Alarifi, Abdullah
p. 126 - 136
(2016/03/09)

Synthesis, characterization and antimicrobial evaluation of novel (E)-N′-(4-(1-((3,4-dimethoxypyridin-2-yl)methyl)-1H-1,2,3-triazol-4-yl)benzylidene)benzohydrazide derivatives
The synthesis of novel 1,2,3-triazole-hydrazone derivatives embedded with 3,4-dimethoxy pyridine ring nucleus is described. These derivatives were prepared utilizing, 2-(chloromethyl)-3,4-dimethoxypyridine 1, 4-ethynylbenzaldehye 5 and various benzohydrazides7a-7j. The structures of the newly synthesized 1,2,3-triazole-hydrazones 8a-j was established on the basis of the spectroscopic techniques like 1H NMR, mass and IR data. They were evaluated against a panel of bacterial and fungal pathogens such as Staphylococcus. pyogens, Staphylococcus. Aureus (Gram positive bacteria), Escherichia.coli, Pseudomonas. aeruginosa (Gram negative bacteria) and Aspergillus niger and Candida albicans (Fungal stains). Compounds 8b, 8c, 8d, 8e and 8f with R = 4-OH, 4-OMe, 4-SO2Me, 3,45,-OMe and 3-NO2 respectively showed moderate antibacterial activity while compounds 8b, 8d, 8i and 8j with R = 4-OH, 4-SO2Me, 3,5-dichloro and 2,5-difluoro substitution exhibited very good fungal activity.
Saidugari, Swamy,Vadali, Lakshmana Rao,Vidya,Ram
p. 2155 - 2161
(2016/10/24)

Design, synthesis, pharmacological evaluation and molecular docking studies of substituted oxadiazolyl-2-oxoindolinylidene propane hydrazide derivatives
The manuscript describes design and synthesis of novel oxadiazolyl-2-oxoindolinylidene propane hydrazides as amide tethered hybrids of indole and oxadiazole and their evaluation for antiinflammatory and analgesic activity. The compounds were synthesized following five step reaction to yield fifteen derivatives as 3-(5-substituted-1,3,4-oxadiazol-2-yl)-N′-[2-oxo-1,2-dihydro-3Hindol-3-ylidene]propane hydrazides. The final derivatives 3-[5-(4-hydroxyphenyl)-1,3,4-oxadiazol-2-yl]-N′-[2-oxo-1,2-dihydro-3H-indol-3-ylidene]propane hydrazide and 3-[5-(4-methylphenyl)-1,3,4-oxadiazol-2-yl]-N′-[2-oxo-1,2-dihydro-3H-indol-3-ylidene]propane hydrazide were found to be highly promising molecules with severity index of 0.35 and 0.56, respectively, which is promising for an analgesic compound. The hydroxy and methyl substitution on phenyl ring system provided with active anti-inflammatory compounds having increase in reaction time of 84.11 and 83.17percent, respectively compared to standard drug at 85.84percent. Molecular docking studies exhibit comparable interaction with synthesized derivatives and standard drug having a dock score of -4.44 by the K-nearest neighbour genetic algorithm method.
Kerzare, Deweshri,Chikhale, Rupesh,Bansode, Ratnadeep,Amnerkar, Nikhil,Karodia, Nazira,Paradkar, Anant,Khedekar, Pramod
p. 1998 - 2010
(2016/11/03)

Synthesis and antibacterial activity of some new quinaxaline-benzohydrazides
Quinoxalines have been found to exhibit various biological activities such as antibacterial, antifungal, anti-tubercular, anxiolytic, anticancer, antioxidant, anti-inflammatory, anti-HIV, antihelmintic and anticonvulsant. The present study aims towards synthesis, characterization and determination of antimicrobial susceptibility testing of various novel quinoxaline derivatives. The quinoxaline-benzohydrazides 6a-m have been obtained by the condensation of quinoxaline-2-carboxaldehyde 4 with various benzohydrazides 5a-m in ethanol at reflux temperature. All the newly synthesized quinoxaline-benzohydrazide derivatives have been characterized by 1H NMR, IR and mass spectroscopic analysis. The synthesized quinoxaline-benzohydrazides 6a-m have been screened for antibacterial activity. Most of the compounds show significant antibacterial activity.
Haripriya,Laxminarayana,Thirumala Chary
p. 207 - 212
(2017/01/18)

Oxidative Esterification of Aromatic Aldehydes Using Polymer-Supported Green Bromine
A facile one-pot green chemical conversion of aromatic aldehydes to alkyl esters is described using polymer-supported bromine chloride resin in the presence of potassium carbonate at room temperature. This eco-friendly methodology with simple workup procedure and recovery and recyclability of the resin makes the transformation simple and efficient.
Sridhar,Swarnalakshmi,Selvaraj
p. 1344 - 1348
(2016/06/01)

ZnII and CdII MOFs based on an amidoisophthalic acid ligand: Synthesis, structure and catalytic application in transesterification
Solvothermal reaction of zinc(ii) and cadmium(ii) salts with 5-propionamidoisophthalic acid (H2L1) and 5-benzamidoisophthalic acid (H2L2) in the presence or absence of an auxiliary ligand gives rise to a series of 1D, 2D and 3D Zn(ii) or Cd(ii) self-assembled metal-organic frameworks as revealed by X-ray diffraction structural analyses: [Zn(μ-L1-μ-1κOO′:2κO′′)(formamide)2]n (1), [{Zn2(μ-L1-1κO:2κO′)2(4,4′-bipyridine)2(H2O)}·2(DMF)·5(H2O)]n (2), [Cd(μ-L1-μ-1κO2O′:2κO′′2O′′′)(DMF)]n (3), [{Zn(μ-L2-1κO:2κO′)(4,4′-bipyridine)(H2O)}·(H2O)]n (4) and [{Cd(μ-L2-μ-1κO2O′:2κO′′2O′′′)(formamide)(4,4′-bipyridine)}·(formamide)]n (5), which are also characterized by elemental analysis, IR spectroscopy and thermogravimetric analysis. The different architectures found in 1-5 result from the coordination modes of the carboxylate groups, which can assume nonbridging monodentate (in 1, 2 and 4), bridging bidentate (also in 1), bridging chelate (in 3 and 5) and chelate bidentate (also in 5) coordination. While 1 and 5 possess one dimensional double chain type structures, 3 has a 1D cyclic type structure and 2 and 4 have 2D or 3D wave-like structures, respectively. Topological analysis has shown that 1 and 5 have a 3-connected uninodal net with a topological type SP1-periodic net, 2 has a 2,4-connected binodal net, 3 has a 4-connected uninodal net structure and 4 has a more complex 2,2,2,4-connected tetranodal net. Frameworks 1-5 act as heterogeneous catalysts for the transesterification reaction of different carboxylate esters, with 4 showing the highest activity. These heterogeneous catalysts can be recycled without losing activity.
Karmakar, Anirban,Rúbio, Guilherme M. D. M.,Guedes da Silva, M. Fátima C.,Ribeiro, Ana P. C.,Pombeiro, Armando J. L.
p. 89007 - 89018
(2016/10/03)

Synthesis, Structural Analysis, and Screening of Some Novel 5-Substituted Aryl/Aralkyl-1,3,4-Oxadiazol-2-Yl 4-(Morpholin-4-Ylsulfonyl)Benzyl Sulfides As Potential Antibacterial Agents
A series of new 5-substituted aryl/aralkyl-1,3,4-oxadiazol-2-yl 4-(morpholin-4-ylsulfonyl)benzyl sulfides 6a-k were synthesized by converting multifarious aryl/aralkyl organic acids 1a-k successively into corresponding esters 2a-k, hydrazides 3a-k, and 5-substituted aryl/aralkyl-1,3,4-oxadiazole-2-thiols 4a-k. Finally, the target compounds, 6a-k were prepared by stirring 5-substituted-1,3,4-oxadiazole-2-thiols with 4-(4-(bromomethyl)phenylsulfonyl) morpholine (5) in the presence of N,N-dimethylformamide (DMF) and sodium hydride (NaH). The structures of the newly synthesized compounds were elucidated by spectroscopic techniques. In addition, the antibacterial activity of all the synthesized compounds was investigated in vitro against Gram-positive and Gram-negative bacteria by using ciprofloxacin as reference standard drug and the results showed that some of the tested compounds possessed good antibacterial activity.
Aziz-Ur-Rehman,Gul, Samreen,Abbasi, Muhammad Athar,Nafeesa, Khadija,Akhtar, Muhammad Nadeem,Ahmad, Irshad,Afzal, Saira
p. 1045 - 1055
(2015/08/04)

Synthesis of novel triazoles and a tetrazole of escitalopram as cholinesterase inhibitors
A novel serie of escitalopram triazoles (60-88) and a tetrazole (89) have been synthesized and subjected to a study to establish the inhibitory potential of these compounds toward acetylcholinesterase (AChE) and butyrylcholinesterase (BChE). Some selectivity in inhibition has been observed. The 4-chlorophenyl- (75, IC50, 6.71 ± 0.25 μM) and 2-methylphenyl- (70, IC50, 9.52 ± 0.23 μM) escitalopram triazole derivatives depicted high AChE inhibition, while 2-fluorophenyl- (76, IC50 = 4.52 ± 0.17 μM) and 4-fluorophenyl- (78, IC50 = 5.31 ± 0.43 μM) have found to be excellent BChE inhibitors. It has also been observed that ortho, meta and para substituted electron donating groups increase the inhibition, while electron withdrawing groups reduce the inhibition. Docking analyses of inhibitors with AChE have depicted the binding energies for 70 and 75 as ΔGbind -6.42 and -6.93 kcal/mol, respectively, while ligands 76 and 78 have shown the binding affinity ΔGbind -9.04 and -8.51 kcal/mol, respectively, for BChE.
Mehr-Un-Nisa,Munawar, Munawar A.,Chattha, Fauzia A.,Kousar, Samina,Munir, Jawaria,Ismail, Tayaba,Ashraf, Muhammad,Khan, Misbahul A.
p. 6014 - 6024
(2015/11/11)

Synthesis and antimicrobial activity of new imidazole-hydrazone derivatives
Hydrazones demonstrated significant antimicrobial activity, antitubercular activity and antitumoral activity in medicinal areas. The imidazole nucleus is well known to play an important role in living organisms since it is incorporated into the histidine molecule and many other important biological, pharmacological and therapeutic activities. Condensation of 4-phenyl-1H-imidazole-2-carbaldehyde (3) with various selected benzohydrazides (4a-m) resulted in imidazole-hydrazone derivatives (5a-m). They were evaluated for antibacterial and antifungal activity against A. Niger, C. albicans (fungal strains), E. coli and P. aeruginosa (Gram-negative bacteria), S. aureus and S. pyogenes (Gram-positive bacteria) using griseofluvin (for fungi) and ciprofloxacin (for bacteria) as the standard drugs. In general, it is observed that most of the compounds were found to be potent against both the bacterial and fungal strains.
Prasanna, V. Laxmi,Narender
p. 3605 - 3608
(2015/12/24)

Palladium supported on triphenylphosphine functionalized porous organic polymer: A highly active and recyclable catalyst for alkoxycarbonylation of aryl iodides
An efficient method for the alkoxycarbonylation of aryl iodides using palladium supported on triphenylphosphine functionalized porous organic polymer (Pd@KAPs(Ph-PPh3)) as the catalyst is reported. Under balloon pressure of CO, various aryl iodides on carbonylation with alcohols and phenols give the corresponding products in moderate to excellent yields (74-96%). The catalyst can be easily separated by simple filtration process and recycled up to ten times without significant decrease in activity. The salient features of this protocol are the simplicity in handling of the catalyst, low CO pressure, negligible palladium leaching and good catalyst recyclability.
Lei, Yizhu,Wu, Linjuan,Zhang, Xuefeng,Mei, Hui,Gu, Yanlong,Li, Guangxing
p. 164 - 169
(2015/02/19)

Synthesis, biologicalevaluation, and molecular modeling of (E)-2-aryl-5-styryl-1,3,4-oxadiazolederivatives as acetylcholine esterase inhibitors
A library of 2,5-disubstituted 1,3,4-oxadiazole derivatives of (E)-2-aryl-5-(3,4,5-trimethoxystyryl)-1,3,4-oxadiazoles 4(a-o) and (E)-2-aryl-5-(2-benzo[d][1,3]dioxol-5-yl)vinyl)-1,3,4-oxadiazoles 5(a-q) were synthesized and evaluated for their in vitro acetylcholinesterase (AChE) inhibitory activity. All the synthesized compounds exhibited moderate to good inhibitory activity toward the AChE enzyme. Among the oxadiazole derivatives examined, compounds 4a, 4g, 5c, and 5m (IC50 values of 24.89, 13.72, 37.65, and 19.63 μM, respectively) were found to be promising inhibitors of AChE. Molecular protein-ligand docking studies were examined for these compounds using GOLD docking software and their binding conformations were determined and the simultaneous interactions mode was also established for the potent derivatives. Springer Science+Business Media 2013.
Kamal, Ahmed,Shaik, Anver Basha,Reddy, G. Narender,Kumar, C. Ganesh,Joseph, Joveeta,Kumar, G. Bharath,Purushotham, Uppula,Sastry, G. Narahari
p. 2080 - 2092
(2014/05/06)

Novel arylhydrazone derivatives bearing a rhodanine moiety: Synthesis and evaluation of their antibacterial activities
A series of arylhydrazone derivatives bearing a rhodanine moiety have been synthesized, characterized, and evaluated as antibacterial agents. Some of these compounds showed potent antibacterial activities against several different strains of Gram-positive bacteria, including multidrug-resistant clinical isolates. Of the compounds tested, IIk and IIIk were identified as the most effective, with minimum inhibitory concentration values of 2-4 μg/mL against multidrug-resistant Gram-positive organisms, including methicillin-resistant and quinolone-resistant Staphylococcus aureus. None of the compounds exhibited any activity against the Gram-negative bacteria Escherichia coli 1356 at 64 μg/mL.
Li, Wei,Zheng, Chang-Ji,Sun, Liang-Peng,Song, Ming-Xia,Wu, Yan,Li, Yin-Jing,Liu, Yi,Piao, Hu-Ri
p. 852 - 861
(2014/08/05)

Synthesis and antitumor activities of novel hybrid molecules containing 1,3,4-oxadiazole and 1,3,4-thiadiazole bearing Schiff base moiety
A series of novel hybrid molecules containing 1,3,4-oxadiazole and 1,3,4-thiadiazole bearing Schiff base moiety were designed, synthesized and evaluated for their in vitro antitumor activities against SMMC-7721, MCF-7 and A549 human tumor cell lines by CCK-8 assay. The bioassay results demonstrated that most of the tested compounds showed potent antitumor activities, and some compounds exhibited stronger effects than positive control 5-fluorouracil (5-FU) against various cell lines. Among these compounds, compound 8d showed the best inhibitory effect against SMMC-7721 cells, with IC50 value of 2.84 μM. Compounds 8k and 8n displayed highly effective antitumor activities against MCF-7 cells, with IC50 values of 4.56 and 4.25 μM, respectively. Compounds 8a and 8n exhibited significant antiproliferative activity against A549 cells, with IC50 values of 4.11 and 4.13 μM, respectively. The pharmacological results suggest that the substituents of phenyl ring on the 1,3,4-oxadiazole are vital for modulating antiproliferative activities against various tumor cell lines.
Zhang, Kai,Wang, Peng,Xuan, Li-Na,Fu, Xiao-Yun,Jing, Fen,Li, Sha,Liu, Yu-Ming,Chen, Bao-Quan
p. 5154 - 5156
(2014/12/11)

Inclusion complex containing epoxy resin composition for semiconductor encapsulation
The invention is an epoxy resin composition for sealing a semiconductor, including (A) an epoxy resin and (B) a clathrate complex. The clathrate complex is one of (b1) an aromatic carboxylic acid compound, and (b2) at least one imidazole compound represented by formula (II): wherein R2 represents a hydrogen atom, C1-C10 alkyl group, phenyl group, benzyl group or cyanoethyl group, and R3 to R5 represent a hydrogen atom, nitro group, halogen atom, C1-C20 alkyl group, phenyl group, benzyl group, hydroxymethyl group or C1-C20 acyl group. The composition has improved storage stability, retains flowability when sealing, and achieves an effective curing rate applicable for sealing delicate semiconductors.
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(2014/03/21)

Zinc metal-organic frameworks: Efficient catalysts for the diastereoselective Henry reaction and transesterification
Three new compounds bearing different flexible side functional groups, viz. 2-acetamidoterephthalic acid (H2L1), 2-propionamidoterephthalic acid (H2L2) and 2-benzamidoterephthalic acid (H2L3), were synthesized and their coordination reactions with zinc(ii) were studied. X-ray crystallography showed the formation of novel metal organic frameworks with different dimensionalities, where the side functional groups of amidoterephthalic acid and/or auxiliary ligands were found to play significant roles. These frameworks [Zn2(L1)2(4,4′-bipyridine) 2(H2O)(DMF)]n (1), [Zn4(L2) 3(OH)2(DMF)2(H2O)2] n (2) and [Zn(L3)(H2O)2]n·n/ 2(1,4-dioxane) (3) act as heterogeneous polymeric solid catalysts not only for the diastereoselective nitroaldol (Henry) reaction of different aldehydes with nitroalkanes but also for transesterification reactions. These MOF-based heterogeneous catalysts can be recycled without losing their activity. This journal is the Partner Organisations 2014.
Karmakar, Anirban,Guedes Da Silva, M. Fatima C.,Pombeiro, Armando J. L.
p. 7795 - 7810
(2014/05/20)

A catalyst-free protocol for direct oxidative esterification of alcohols and aldehydes
A fast, simple, and efficient protocol for the direct conversion of alcohols and aldehydes to methyl ester has been developed using TsNBr2without any catalyst. The one pot reaction proceeds in the presence of a base at room temperature in methanol, to produce the corresponding methyl ester in high yield within a short time.
Rajbongshi, Kamal Krishna,Sarma, Manas Jyoti,Phukan, Prodeep
p. 5358 - 5360
(2015/01/08)

N′-[4-[(Substituted imino)methyl]benzylidene]-substituted benzohydrazides: Synthesis, antimicrobial, antiviral, and anticancer evaluation, and QSAR studies
A variety of N′-[4-[(substituted imino)methyl]benzylidene]- substituted benzohydrazides have been synthesized and evaluated for antimicrobial and anticancer potential. Results from testing of antimicrobial activity indicated the most potent antimicrobial agents had pMIC am = 1.51. The synthesized compounds were bacteriostatic and fungistatic in action. Results from evaluation of antiviral activity indicated that none of the synthesized hydrazide derivatives inhibited viral replication at sub-toxic concentrations. Results from anti-HIV screening against HIV-2 strain ROD indicated that one compound was more potent (IC 50 ≥ 1 μg/cm3) than the standard drug nevirapine (IC 50 ≥ 4 μg/cm3) and another was equipotent (IC 50 ≥ 4 μg/cm3). The most effective anticancer agent against both HCT116 and MCF7 cancer cell lines had IC 50 = 19 and 18 μg/cm 3, respectively. QSAR analysis indicated the importance of Wiener index (W) and energy of the lowest unoccupied molecular orbital (LUMO) in describing the antimicrobial activity of the synthesized compounds.
Kumar, Pradeep,Narasimhan, Balasubramanian,Ramasamy, Kalavathy,Mani, Vasudevan,Mishra, Rakesh Kumar,Majeed, Abu Bakar Abdul,De Clercq, Erik
p. 825 - 849
(2013/07/11)

Design, synthesis and biological evaluation of novel arylidine- malononitrile derivatives as non-carboxylic inhibitors of protein tyrosine phosphatase 1B
In this study, we describe the design, synthesis, biological evaluation and molecular modelling studies of novel non-carboxylic arylidine malononitrile-based molecules as Protein Tyrosine Phosphatase 1B (PTP1B) inhibitors. The synthesized derivatives were evaluated in vitro for glucose reuptake using L6 muscle cell lines and enzymatic assay against PTP1B. The biological activity results showed that the 2-methoxy substituted (14b) compound exhibited significant activity in both the assays. The unsubstituted compound (14a) also possessed comparable activity on glucose reuptake in L6 muscle cell lines and better inhibitory activity on PTP1B enzyme assays. Docking analysis was performed on the most potent compound of the series to understand the nature of interactions governing the binding of the designed molecule with the PTP1B enzyme.
Deora, Girdhar Singh,Karthikeyan, Chandrabose,Moorthy, N. S. Hari Narayana,Rathore, Vandana,Rawat, Arun K.,Tamrakar, Akhilesh K.,Srivastava,Trivedi, Piyush
p. 5344 - 5348
(2013/12/04)

An unusual 1,2-aryl shift in palladium-catalyzed cross-coupling ethoxycarbonylation of arylboronic acids with α-iminoesters
The Pd-catalyzed cross-coupling ethoxycarbonylation of aryl boronic acids with N-aryl-α-iminoesters affords aryl carboxylic esters via carbonyl-imino σ bond cleavage. This unprecedented mode of reaction allows regioselective installation of the ethoxycarbonyl group into target molecules. Mechanism studies have revealed that an unusual 1,2-aryl shift process is involved in the transformation. The Royal Society of Chemistry.
Qian, Cheng,Chen, Jiayan,Fu, Meiqin,Zhu, Shiya,Chen, Wen-Hua,Jiang, Huanfeng,Zeng, Wei
p. 6013 - 6022
(2013/09/12)

Manganese phthalocyanine immobilized on silica gel: Efficient and recyclable catalyst for single-step oxidative esterification of aldehydes with alcohols
The functionalization of silica gel was carried out using 3-aminopropyltriethoxysilane as a reactive surface modifier followed by covalent grafting of novel tetrakis-(2-methoxy-4-formylphenoxy)phthalocyaninato manganese(III) acetate complex. The resulting inorganic-organic hybrid material was found to be a highly selective and recyclable catalyst for the single-step synthesis of esters. The catalyst was characterized by elemental analysis (CHN), diffuse reflectance UV-visible, 13C CPMAS and 29Si CPMAS NMR spectroscopy, X-ray diffraction (XRD), scanning electron microscopy (SEM), BET surface area analysis, energy dispersive X-ray fluorescence (ED-XRF), Fourier-transform infrared (FT-IR) and atomic absorption spectroscopy (AAS) techniques, which demonstrates the covalent grafting of the complex onto functionalized silica gel. The catalytic performance of the novel inorganic-organic hybrid catalyst was evaluated in the direct oxidative esterification of aldehydes with alcohols, at ambient temperature, using hydrogen peroxide as an environment friendly oxidant. The hybrid catalyst presented up to 100% of substrate conversion with high turn-over numbers (TONs), up to 100% of selectivity toward the ester product, and can be recovered and reused for multiple cycles without appreciable loss in its catalytic activity.
Sharma,Gulati, Shikha
p. 291 - 303
(2012/10/30)

Ligand free palladium catalyzed decarboxylative cross-coupling of aryl halides with oxalate monoester salts
Ligand free Pd-catalyzed decarboxylative cross-coupling of potassium oxalate monoester and derivatives with aryl iodides and bromides is described. Functionalized aromatic esters can be efficiently synthesized via this method with only 1.0 mol % Pd(OAc)2 catalyst without any phosphine ligand. This method illustrates an inexpensive and operationally simple method for the preparation of aromatic esters and acids, which is especially beneficial for a large scale synthesis.
Li, Yan,Chen, Huan-Huan,Wang, Chu-Fei,Xu, Xiao-Lan,Feng, Yi-Si
p. 5796 - 5799
(2012/10/29)

Oxidative cross-esterification of dithiolanes with alcohols through a cross-dehydrogenative coupling (CDC)/deprotection sequence
An unprecedented oxidative cross-esterification in an equimolar mixture of dithiolanes, alcohols and water through a CDC/deprotection sequence has been developed. The reaction itself features simple experimental procedures under very mild conditions and offers a new strategic protocol for the direct and efficient synthesis of structurally diverse esters.
Fu, Liang,Yao, Chang-Jiang,Chang, Ning-Jie,Chen, Jia-Rong,Lu, Liang-Qiu,Xiao, Wen-Jing
p. 506 - 508
(2012/01/15)

A clean, palladium-catalyzed oxidative esterification of aldehydes using benzyl chloride
A highly efficient, mild, simple and clean procedure is presented for the one-pot oxidation of aromatic and aliphatic aldehydes to their corresponding ethyl esters using benzyl chloride as the oxidant under palladium-catalyzed conditions. The reaction is complete in just 30 min under microwave irradiation and inert conditions are not required to obtain good to excellent yields (65-93%) of isolated products.
Heropoulos, Georgios A.,Villalonga-Barber, Carolina
experimental part
p. 5319 - 5322
(2011/10/31)