- Preparation and characterization of a synthetic curcumin analog inclusion complex and preliminary evaluation of in vitro antileishmanial activity
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The aim of this work was to prepare and characterize inclusion complexes between a synthetic curcumin analog (dibenzalacetone, DBA) and beta-cyclodextrin (β-CD); and to evaluate their in vitro antileishmanial activity. DBA was synthetized and characterized by spectroscopic methods and the inclusion complexes were obtained by kneading and lyophilization (LIO) in 1:1 and 1:2 stoichiometries. Phase solubility and dissolution assays showed a 40-fold increase in the aqueous solubility of DBA and its complete dissolution from LIO 1:1 formulation after 120 min respectively. Solid-state characterization by differential scanning calorimetry and near infrared spectroscopy demonstrated the inclusion of DBA in the β-CD cavity at the molar ratios tested, with LIO 1:1 formulation being the most stable. Using nuclear magnetic resonance experiments, the protons inside the cavity of β-CD were the most affected after the inclusion of DBA molecule. The cellular viability of THP-1 macrophage cells treated with plain DBA, β-CD and DBA/CD inclusion complexes showed that the plain DBA and DBA/CD at 1:2 stoichiometry presented toxicity, while β-CD alone and DBA/CD at 1:1 stoichiometry showed no toxicity up to 640 μg mL?1. The in vitro assay with free-living promastigotes demonstrated that plain DBA and β-CD had IC50 of 320 μg mL?1 respectively, while only inclusion complexes with 1:1 stoichiometry showed antiproliferative activity with IC50 = 51.3 μg mL?1. Using the amastigote intracellular forms, there was also a difference between the plain and β-CD complexed DBA with complexes of 1:1 and 1:2 stoichiometry presenting EC50 = 66.3 μg mL?1 and 58.9 μg mL?1 respectively. The study concluded that DBA/CD at 1:1 molar ratio has the potential to decrease the intrinsic toxicity of plain DBA towards Leishmania host cells, which may be a therapeutic advantage in the application of these compounds.
- Adeoye, Oluwatomide,Cabral-Marques, Helena,Carvalheiro, Manuela Colla,Francisco, Ana Paula,Pinto, Luciana Matos Alves,Thomasi, Sérgio Scherrer
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- Wet chemical epitaxial growth of a cactus-like CuFeO2/ZnO heterojunction for improved photocatalysis
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Herein, a wet chemical epitaxial growth method was employed to fabricate a cactus-like CuFeO2/ZnO heterojunction for the photocatalytic reduction of benzaldehyde to benzyl alcohol. The 1D ZnO nanorods in the heterojunction make contact with the 2D CuFeO2 nanoflakes at the atomic level, therefore providing a fast charge transfer channel along the direction parallel to the CuFeO2c-axis, leading to efficient charge separation and improved photocatalytic performance.
- Jiang, Tengfei,Tian, Jingqi,Xu, Cong,Xue, Huaiguo,Zhang, Yihan
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- Synthesis, crystal growth and characterization of 1,5-diphenylpenta-1,4- dien-3-one: An organic crystal
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1,5-Diphenylpenta-1,4-dien-3-one ( dibenzalacetone, DBA) was synthesized by a base-catalyzed aldol condensation reaction between benzaldehyde and acetone. High quality single crystals have been grown by the slow evaporation of ethanol solution and the crystal belongs to monoclinic system with centrosymmetric space group C 2/c. The DBA crystals are transparent in the entire visible region and have a lower optical cutoff at ～440 nm. It is stable up to 119 °C and has a good chemical stability. The high resolution X-ray diffraction curve (DC) indicates that the specimen is free from structural grain boundaries. Molecular packing leads to a centrosymmetric arrangement resulting in zero second harmonic generation (SHG; X(2)=0) efficiency.
- Vanchinathan,Bhagavannarayana,Muthu,Meenakshisundaram
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Read Online
- Spectral investigation and structural characterization of Dibenzalacetone: β-Cyclodextrin inclusion complex
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The interaction of Dibenzalacetone (DBA) with β-Cyclodextrin (β-CD) producing an inclusion complex was carried out by co-precipitation method. The binding constant was determined using steady state and time-resolved fluorescence spectroscopy and the results suggested that the inclusion complex preferred 1:1 stoichiometry. The complex was characterized by UV-Visible, infrared spectroscopy (FT-IR), differential scanning calorimetry (DSC) and X-ray diffractometry (XRD). The morphological characteristics of the solid complex were analyzed by Scanning electron microscope (SEM) and Atomic force microscope (AFM). The structure of 1:1 inclusion complex of DBA with β-CD is proposed. The Docking study reveals that this structure was found to be highly probable and energitically favorable model.
- Periasamy,Rajamohan,Kothainayaki,Sivakumar
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Read Online
- Synthesis of lithium/cesium-Zagronas from zagrosian natural asphalt and study of their activity as novel, green, heterogeneous and homogeneous nanocatalysts in the Claisen–Schmidt and Knoevenagel condensations
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A novel, heterogeneous and homogeneous basic nanocatalysts were synthesized by grafting of lithium and cesium on zagrosian natural asphalt sulfonate (Li/Cs-Zagronas). The activity of these catalysts was examined in the Claisen–Schmidt and Knoevenagel condensations under mild reaction conditions. Li/Cs-Zagronas were characterized by FT-IR spectroscopy, scanning electron microscopy, X-ray diffraction, energy-dispersive spectroscopy, inductively coupled plasma and thermogravimetric analysis techniques. These nanocatalysts were removed by simple filtration and reused several times without any deterioration of activity.
- Soleiman-Beigi, Mohammad,Ghalavand, Saba,Venovel, Hadis Gholami,Kohzadi, Homa
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p. 3267 - 3279
(2021/06/17)
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- In vitro and in silico growth inhibitory, anti-ovarian & anti-lung carcinoma effects of 1,5 diarylpenta-1,4-dien-3-one as synthetically modified curcumin analogue
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The synthesized 1,5 diarylpenta-1,4-dien-3-one derivatives (compounds 1-6) as synthetic curcumin analogues were tested for their potential anticancer activity against human ovarian and lung adenocarcinoma cells. The absorption, distribution, metabolism, excretion, and toxicity (ADMET/pharmacokinetic) parameters of all the compounds were predicted by admetSAR software. The pharmacokinetics, pharmacodynamics and bioactivity scores properties based on Lipinski rule and Ghose filter, calculated with the help of Molinspiration and ChemDraw. Molecular docking evaluation of all the compounds was also performed by using AutoDock Vina and iGEMDOCK against three most common human anticancer targets; epidermal growth factor receptor (EGFR), heat shock protein (Hsp 90-α), and vascular endothelial growth factor receptor-2 (VEGFR2). The obtained results were compared with the reference compound 7 and drugs 8-10 (7: GO-035; 8: Quinazolin; 9: Naquotinib and 10: Ribofuranuronamide). Finding indicates, all the compounds were potentially interacting with VEGFR2 through the average –9.1 binding energy (BE) with closer contact 1H-NMR). In vitro anti-proliferative activity was tested via MTT method against human ovarian carcinoma (PA-1) and human lung adenocarcinoma (A549) cells and further screened for apoptotic parameters such as nuclear fragmentation and ROS generation. Compound 4 exhibits good dose-dependent anti-proliferative activity (IC50 73 and 79.7 μM) against human ovarian carcinoma and human lung adenocarcinoma, respectively. Communicated by Ramaswamy H. Sarma.
- Chowrasia, Deepak,Jafri, Asif,Azad, Iqbal,Rais, Juhi,Sharma, Nisha,Khan, Fahad,Kumar, Ajay,Kumar, Sudhir,Arshad, Md
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- Heterogeneous acid catalyzed synthesis and spectroscopic characterization of schiff bases derived from chalcone derivatives
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Schiff bases have continued to gain attention as essential building blocks and versatile pharmacophores in drug development and drug-like molecular entities. Thus, the synthesis of Schiff bases was achieved herein via facile acetic acid catalyzed synthetic transformation of chalcones. The targeted Schiff bases and related compounds 2a-m were accessed by the treatment of amines with chalcone 1 which was previously derived through Claisen-Schmidt reaction between benzaldehyde and acetone, at ambient temperature. Structural characterization was achieved via physicochemical properties and the use of IR, UV, 1H and 13C NMR which were spectroscopic techniques. The compounds have essential candidature for further study, in biological activity so as to unleash their medicinal potential.
- Ajani, Olayinka O.,Jolayemi, Emmanuel G.,Owolabi, Fisayo E.,Tolu-Bolaji, Olayinka O.,Audu, Oluwatosin Y.
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p. 193 - 200
(2021/01/18)
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- Synthesis and (fluoro)solvatochromism of two 3-styryl-2-pyrazoline derivatives bearing benzoic acid moiety: A spectral, crystallographic and computational study
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In this work we report the synthesis of two fluorescent 2-pyrazoline derivatives exhibiting remarkable (fluoro)solvatochromic behavior. The pyrazolines were synthesized in one step from the corresponding monocarbonyl curcuminoids and 4-hydrazinobenzoic acid in high yield and purity and were fully characterized by means of NMR and FT-IR spectroscopy and HRMS spectrometry. The structure of the novel derivative 2 was also characterized by means of X-ray crystallography. Both compounds were studied computationally in the gas phase. Additionally, the effects of solvent polarity on the absorption and fluorescence spectra of these derivatives were investigated in a solvent group consisting of various neat molecular solvents exhibiting hydrogen bond donating (HBD), hydrogen bond accepting (HBA), and/or dipolar behavior. The solvent effects observed were quantified and rationalized by employing suitable multiparametric Linear Solvation Energy Relationships (LSERs) involving dipolarity, HBD-acidity and HBA-basicity terms. The contribution of each of these parameters provided insights on the predominant solute-solvent interactions occurring in solution. Importantly, some differences in the (fluoro)solvatochromic aptitude/behavior were revealed among the derivatives and they were rationalized on the basis of their structural diversity.
- Matiadis, Dimitris,Nowak, Katarzyna E.,Alexandratou, Eleni,Hatzidimitriou, Antonios,Sagnou, Marina,Papadakis, Raffaello
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- Bola-type PAH-based fluorophores/chemosensors: Synthesis via an unusual clemmensen reduction and photophysical studies
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Bola-type organic scaffolds are of key importance for application in a wide variety of fields. In this manuscript we wish to report our results on construction of polycyclic aromatic hydrocarbon (PAH, PAH = 9-antracenyl, 1-pyrenyl)-based bola-type fluorophores/chemosensors via an unusual Clemmensen reduction of the corresponding penta-1,4-dien-3-ones. In aqueous solutions the thus obtained bola-type molecules demonstrate intensive excimer emission at 500 nm, as well as well-pronounced “turn-off” fluorescence response towards common nitro-explosive components, such as 2,4-dinitrotoluene (DNT) and 2,4,6-trinitrotoluene (TNT), as well as, hard-to-detect pentaerythritol tetranitrate (PETN).
- Charushin, V. N.,Chupakhin, O. N.,Gorbunov, E. B.,Grzhegorzhevskii, K. V.,Kovalev, I. S.,Minin, A. S.,Sadieva, L. K.,Taniya, O. S.,Tsurkan, M. V.,Volkova, N. N.,Zyryanov, G. V.
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- Stereoselective synthesis, spectral characterization, docking and biological screening of coumarin derivatives
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The compounds being synthesized in present research are chiral in nature so for getting enantiopure compounds, stereoselective synthesis was carried out by organocatalysis. The importance of enantiopure compounds can not be overstated because the living systems are chiral in nature and response of enantiomers can be very different in living systems. The organocatalysed synthesis was accumplished using 4-hydroxycoumarin and variously substituted dibenzylideneacetones as reactants and the organocatalyst being used was 9-amino-9-deoxyepiquinine. The range of enantioselectivity achieved was 24-95%. The synthesized compounds were characterized by UV, IR, 1H NMR, 13C NMR, EIMS, UVCD, VCD and Chiral HPLC. The major focus of this research was to develop anticoagulant compounds and therefore the molecular docking studies were carried out with crystal structure of vitamin k epoxide reductase (3kp9) and then screened for in-vitro anticoagulant activity by using warfarin as positive control. Out of six synthesized compounds, four compounds (1,2,5,6) have shown greater binding affinity with 3kp9 than warfarin. In in-vitro anticoagulant studies, all compounds showed improved IC50 values than warfarin. Besides anticoagulant activity, antimocrobial activities were also carried out with six different strains of bacteria and fungi. Compound (5) showed 79% inhibition against Bacillus subtillis and 62 % inhibition against Staphylococcus aureus.
- Afzal, Zakia,Nadeem, Humaira,Rashid, Naghmana
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p. 330 - 341
(2021/07/19)
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- Bioinspired CNP Iron(II) Pincers Relevant to [Fe]-Hydrogenase (Hmd): Effect of Dicarbonyl versus Monocarbonyl Motifs in H2 Activation and Transfer Hydrogenation
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A set of bioinspired carbamoyl CNP pincer complexes are reported that are relevant to [Fe]-hydrogenase (Hmd). The dicarbonyl species [(CNHNNHPR2)Fe(CO)2I] [R = Ph, 1; R = iPr, 2] undergoes ligand deprotonation, resulting in the dearomatized complexes of formulas [(CNHNN=PR2)Fe(CO)2] (5 and 6). The crystal structure and 1H{31P} NMR spectroscopy of the iodide-bound dearomatized species [Na(18-crown-6)][(CNHNN=PPh2)Fe(CO)2I] (7) showed that the deprotonated moiety was the phosphoramine N(H) linkage. Separately, the monocarbonyl complexes [(CNHNNHPR2)Fe(CO)(MeCN)2](BF4) (8 and 9) synthesized, as well as deprotonated and dearomatized in similar fashion. Reactivity studies revealed that the parent dicarbonyl complexes require more forceful conditions for H2 activation, compared with the monocarbonyl complexes. The ligand backbone was not found to participate in H2 activation and H2 → hydride transfer to an organic substrate was not observed in either case. Density functional theory calculations revealed that the higher reactivity of the monocarbonyl complex in H2 splitting could be attributed to its higher affinity for H2. This behavior is attributed to two key points related to the requisite dI(Fe) → σ*(H2) back-bonding interaction in a conventional M-H2 Kubas interaction: (i) generally, the weaker πdonor capacity of the dicarbonyls, and (ii) specifically, the detrimental effect of a strongly πacidic CO ligand (versus weakly πacidic MeCN ligand) trans to the H2 activation site. The higher reactivity of the monocarbonyl complex is also evidenced by the catalytic transfer hydrogenation by monocarbonyl 8, whereas dicarbonyl 1 was ineffective. Overall, the results suggest that Nature uses the dicarbonyl motif in [Fe]-hydrogenase to diminish the interaction between the Fe center and dihydrogen, thereby preventing premature H2 activation prior to substrate (H4MPT+) binding and any resulting nonspecific hydride transfer reactivity.
- Chai, Wenrui,Henkelman, Graeme A.,Kerns, Spencer A.,Rose, Michael J.,Xie, Zhu-Lin
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supporting information
(2020/02/22)
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- Preparation method of long-carbon-chain ketone-based dicarboxylic acid ester (by machine translation)
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The preparation method comprises the following steps: (1) adding a solvent and an alkali solution; adding a solvent and an alkali solution; adding a solvent, a catalyst and a base; and adding a solvent, a catalyst and a base to obtain 0 - 80 °C diphenyl 1,5 -1 pentadiene 4 - ketone and the cyclic diketone to a reaction kettle for a certain time and then concentrating and separating -3 -3 -1-4 - diphenyl 2-pentadiene and a cyclic diketone to a reaction 4 - 18h kettle at 1,5 - DEG C to 70 - 140 °C obtain a long-carbon-chain ketone-based dicarboxylic acid ester. (by machine translation)
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Paragraph 0034-0036; 0038-0040; 0042-0044; 0046-0048; 0050
(2020/08/25)
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- A bioinspired microreactor with interfacial regulation for maximizing selectivity in a catalytic reaction
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We report a bioinspired emulsion microreactor composed of an electrical double layer to mimic the functions of cell membranes. This "artificial cell"can modulate the phase-oriented transport of reagents at the oil-liquid interface via the electrical double layer, affording a powerful tool to optimize the selectivity in a catalytic reaction. This journal is
- Han, Chenhui,Li, Xin-Hao,Waclawik, Eric R.,Xu, Haolan,Xu, Jingsan
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supporting information
p. 8059 - 8062
(2020/09/09)
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- Potassium Natural Asphalt Sulfonate (K-NAS): Synthesis and characterization as a new recyclable solid basic nanocatalyst and its application in the formation of carbon–carbon bonds
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In this research, we synthesized and characterized a new heterogeneous basic nanocatalyst and its catalytic application was studied in the Claisen-Schmidt and Knoevenagel condensations. In order to prepare this nanocatalyst, first, the Iranian natural asphalt was sulfonated with the concentrated sulfuric acid and then, converted to the potassium natural asphalt sulfonate (K-NAS). In order to characterization of the nanocatalyst, used of FT-IR spectroscopy, scanning electron microscopy (SEM), energy dispersive spectroscopy (EDS), X-ray diffraction (XRD), inductively coupled plasma (ICP) and thermogravimetric analysis (TGA) techniques. This new basic heterogeneous nanocatalyst have advantages such as being eco-friendly, huge specific surface area, high reactivity and recyclability.
- Falah, Saeid,Soleiman-Beigi, Mohammad,Kohzadi, Homa
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- Electrospray ionization tandem mass spectrometry of monoketone curcuminoids
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Rationale: Although monoketone curcuminoids (MKCs) have been largely investigated due to their biological activities, data on the gas-phase fragmentation reactions of protonated MKCs under collision-induced dissociation (CID) conditions are still scarce. Here, we combined electrospray ionization tandem mass spectrometry (ESI-MS/MS) data, multiple-stage mass spectrometry (MSn), deuterium exchange experiments, accurate-mass data, and thermochemical data estimated by computational chemistry to elucidate and to rationalize the fragmentation pathways of eleven synthetic MKCs. Methods: The MKCs were synthesized by Claisen-Schmidt condensation under basic (1–9) or acidic (10–11) conditions. ESI-CID-MS/MS analyses and deuterium-exchange experiments were carried out on a triple quadrupole mass spectrometer. MSn analyses on an ion trap mass spectrometer helped to elucidate the fragmentation pathways. Accurate-mass data and thermochemical data, obtained at the B3LYP/6–31+G(d,p) level of theory, were used to support the ion structures. Results: The most intense product ions were the benzyl ions ([C7H2R1R2R3R4R5]+) and the acylium ions ([M + H ? C8H3R1R2R3R4R5]+), which originated directly from the precursor ion as a result of two competitive hydrogen rearrangements. Product ions [M + H – H2O]+ and [M + H ? C6HR1R2R3R4R5]+, which are formed after Nazarov cyclization, were also common to all the analyzed compounds. In addition, ?Br and ?Cl eliminations were diagnostic for the presence of these halogen atoms at the aromatic ring, whereas ?CH3 eliminations were useful to identify the methyl and methoxy groups attached to this same ring. Nazarov cyclization in the gas phase occurred for all the investigated MKCs and did not depend on the presence of the hydroxyl group at the aromatic ring. However, the presence and the position of a hydroxyl group at the aromatic rings played a key role in the Nazarov cyclization mechanism. Conclusions: Our results reinforce some aspects of the fragmentation pathways previously published for 1,5-bis-(2-methoxyphenyl)-1,4-pentadien-3-one and 1,5-bis-(2-hydroxyphenyl)-1,4-pentadien-3-one. The alternative fragmentation mechanism proposed herein can explain the fragmentation of a wider diversity of monoketone curcuminoids.
- Vieira, Tatiana M.,Orenha, Renato P.,Crevelin, Eduardo J.,Furtado, Saulo S.P.,Vessecchi, Ricardo,Parreira, Renato L.T.,Crotti, Ant?nio E.M.
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- Naphtho[2,3-: B] furan-4,9-dione synthesis via palladium-catalyzed reverse hydrogenolysis
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A reverse hydrogenolysis process has been developed for two-site coupling of 2-hydroxy-1,4-naphthoquinones with olefins to produce naphtha[2,3-b]furan-4,9-diones and hydrogen (H2). The reaction is catalyzed by commercially available Pd/C without oxidants and hydrogen acceptors, thereby providing an intrinsically waste-free approach for the synthesis of functionalized and potentially biologically relevant naphtha[2,3-b]furan-4,9-diones.
- Li, Jimei,Zhang, Jie,Li, Mingfei,Zhang, Chenyang,Yuan, Yongkun,Liu, Renhua
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supporting information
p. 2348 - 2351
(2019/02/27)
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- Preparation method of high-purity tris(dibenzylideneacetone)dipalladium (0)
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The invention discloses a preparation method of high-purity tris(dibenzylideneacetone)dipalladium (0). The method includes 1, in a nitrogen atmosphere, adding ligand dibenzylideneacetone, palladium dichloride and anhydrous sodium acetate to anhydrous ethanol that is in a stirring state to carry out a heating reaction, and performing filtering to obtain solid bis(dibenzylideneacetone)palladium (0); 2, in a nitrogen atmosphere, adding the solid bis(dibenzylideneacetone)palladium (0) obtained in the step 1 to acetone that is in a stirring state, washing a retained product after filtering, and drying the washed retained product to obtain the tris(dibenzylideneacetone)dipalladium (0). The preparation method has the advantages that the bis(dibenzylideneacetone)palladium (0) is prepared from the anhydrous ethanol, the dibenzylideneacetone, the palladium dichloride and the anhydrous sodium acetate at first, and then is treated by an acetone solution to obtain the tris(dibenzylideneacetone)dipalladium (0), and accordingly, the obtained tris(dibenzylideneacetone)dipalladium (0) has high purity.
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Paragraph 0019; 0022-0023
(2019/10/04)
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- Exploration of synthetic antioxidant flavonoid analogs as acetylcholinesterase inhibitors: an approach towards finding their quantitative structure–activity relationship
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The binding interactions between acetylcholinesterase (AChE) and a series of antioxidant flavonoid analogs were studied by fluorescence spectroscopic assay. The present study incorporated different classes of naturally occurring and synthetic flavonoid compounds like flavones, isoflavones, and chalcones as well as a few standard antioxidants. The AChE inhibitory (AChEI) activity of these compounds was further analyzed using in silico techniques, namely pharmacophore mapping, quantitative structure–activity relationship (QSAR) analysis, and molecular docking studies. We have also compared the AChE inhibitory and radical scavenging antioxidant activities of these compounds. Both the AChE inhibitory and antioxidant activities of these compounds were found to be highly dependent on their structural patterns. However, it was observed that, in general, flavones are comparatively better AChE inhibitors as well as antioxidants compared to chalcones. [Figure not available: see fulltext.].
- Karmakar, Abhijit,Ambure, Pravin,Mallick, Tamanna,Das, Sreeparna,Roy, Kunal,Begum, Naznin Ara
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p. 723 - 741
(2019/04/17)
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- Modular Pincer-type Pyridylidene Amide Ruthenium(II) Complexes for Efficient Transfer Hydrogenation Catalysis
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A set of bench-stable ruthenium complexes with new N,N,N-tridentate coordinating pincer-type pyridyl-bis(pyridylideneamide) ligands was synthesized in excellent yields, with the pyridylidene amide in meta or in para position (m-PYA and p-PYA, respectively). While complex [Ru(p-PYA)(MeCN)3]2+ is catalytically silent in transfer hydrogenation, its meta isomer [Ru(m-PYA)(MeCN)3]2+ shows considerable activity with turnover frequencies at 50% conversion TOF50 = 100 h-1. Spectroscopic, electrochemical, and crystallographic analyses suggest considerably stronger donor properties of the zwitterionic m-PYA ligand compared to the partially π-acidic p-PYA analogue, imparted by valence isomerization. Further catalyst optimization was achieved by exchanging the ancillary MeCN ligands with imines (4-picoline), amines (ethylenediamine), and phosphines (PPh3, dppm, dppe). The most active catalyst was comprised of the m-PYA pincer ligand and PPh3, complex [Ru(m-PYA)(PPh3)(MeCN)2]2+, which reached a TOF50 of 430 h-1 under aerobic conditions and up to 4000 h-1 in the absence of oxygen. The presence of oxygen reversibly deactivates the catalytically active species, which compromises activity, but not longevity of the catalyst. Ligand exchange kinetic studies by NMR spectroscopy indicate that the strong trans effect of the phosphine is critical for high catalyst activity. Diaryl, aryl-alkyl, and dialkyl ketones were hydrogenated with high conversion, and α,β-unsaturated ketones produced selectively the saturated ketone as the only product due to exclusive C=C bond hydrogenation, a distinctly different selectivity from most other transfer hydrogenation catalysts.
- Melle, Philipp,Manoharan, Yanisha,Albrecht, Martin
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supporting information
p. 11761 - 11774
(2018/09/21)
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- Antimicrobial Activity of Monoketone Curcuminoids Against Cariogenic Bacteria
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We evaluated the antimicrobial activity of 25 monoketone curcuminoids (MKCs) against a representative panel of cariogenic bacteria in terms of their minimum inhibitory concentration (MIC) values. Curcumin A (10) displayed promising activity against Streptococcus mutans (MIC?=?50?μg/ml) and Streptococcus mitis (MIC?=?50?μg/ml) as well as moderate activity against S.?sanguinis (MIC?=?100?μg/ml), Lactobacillus casei (MIC?=?100?μg/ml), and Streptococcus salivarius (MIC?=?200?μg/ml). Results indicated higher activity of compound 10 than that of its bis-β-diketone analog. Additionally, compounds 3a (1,5-bis(4-methylphenyl)pentan-3-one) and 7b (1,5-bis(4-bromophenyl)pentan-3-ol) were moderately active against S.?mitis (MIC?=?100?μg/ml) and S.?salivarus (MIC?=?200?μg/ml).
- Vieira, Tatiana M.,dos Santos, Isabella A.,Silva, Thayná S.,Martins, Carlos H. G.,Crotti, Ant?nio E. M.
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- Stereo- and regioselective photocycloaddition of extended alkenes using γ-cyclodextrin
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Photoexcitation of dibenzalacetones (1a-d) in homogeneous media and solid state yields a mixture of products with poor conversions. Irradiation of the reactants complexed to γ-cyclodextrin predominantly affords a single dimer (syn adduct 6) despite the possibility for several monomeric and dimeric products. High selectivity in the cavitand-mediated reaction along with the structural characterization of the inclusion complex provides insight into the supramolecular interactions that drive the self-assembly of the host-guest system.
- Kashyap, Akshay,Bokosike, Treyvon K.,Bhuvanesh, Nattamai,Pattabiraman, Mahesh
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supporting information
p. 6870 - 6875
(2018/10/17)
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- Studies on the synthesis of spiroheterocycles and their derivatives using dimedone as synthetic precursor
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Diarylidene ketones 1a–c, formed by the condensation of acetone with diverse appropriate aryl aldehydes undergo Micheal reaction with dimedone to afford the desired spiro compounds 2a–c. The spirodiarylidene derivatives 3a–l on cyclisation with hydrazine, phenyl hydrazine, hydroxyl amine, urea, thiourea and guanidine carbonate furnish the respective insitu oxidized pyrazole 4a–l, phenylpyrazole 5a–l, isoxazole 6a–l, pyrimidine 7a–l, aminopyrimidine 8a–l. The antibacterial activities of the synthesized compounds have been investigated against the gram negative Escherichia coli and gram positive bacteria Staphylococcus aureus.
- Majumdar, Poulomi,Mohanta, Prajna Parimita,Sahu, Sankarshan,Behera, Ajaya Kumar
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p. 1747 - 1754
(2018/06/18)
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- Kinetic Resolution of β-Hydroxy Carbonyl Compounds via Enantioselective Dehydration Using a Cation-Binding Catalyst: Facile Access to Enantiopure Chiral Aldols
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A practical and highly enantioselective nonenzymatic kinetic resolution of racemic β-hydroxy carbonyl (aldol) compounds through enantioselective dehydration process was developed using a cation-binding Song's oligoethylene glycol (oligoEG) catalyst with p
- Paladhi, Sushovan,Hwang, In-Soo,Yoo, Eun Jeong,Ryu, Do Hyun,Song, Choong Eui
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supporting information
p. 2003 - 2006
(2018/04/16)
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- Gram-scale preparation of dialkylideneacetones through Ca(OH)2-catalyzed Claisen-Schmidt condensation in dilute aqueous EtOH
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A synthetic method of dialkylideneacetones has been developed. Compared with known protocols, the method employed catalytic Ca(OH)2 as the cheap, mild base catalyst and dilute aqueous EtOH (20%, v/v) as the green and safe solvent. The procedure was easily operated: In most cases, the product could be isolated by a simple filtration, and purified by washing with water. This paper provided experimental details of the reactions, which could be applied in gram-scale synthesis and should be a very reliable and practical protocol to prepare these useful compounds in laboratory and at the industrial level.
- Zhang, Hao,Han, Mengting,Yang, Chenggen,Yu, Lei,Xu, Qing
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- Palladium/Rhodium Cooperative Catalysis for the Production of Aryl Aldehydes and Their Deuterated Analogues Using the Water–Gas Shift Reaction
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A novel Pd/Rh dual-metallic cooperative catalytic process has been developed to effect the reductive carbonylation of aryl halides in moderate to good yield. In this reaction, water is the hydride source, and CO serves both as the carbonyl source and the terminal reductant through the water–gas shift reaction. The catalytic generation of the Rh hydride allows for the selective formation of highly hindered aryl aldehydes that are inaccessible through previously reported reductive carbonylation protocols. Moreover, aldehydes with deuterated formyl groups can be efficiently and selectively synthesized using D2O as a cost-effective deuterium source without the need for presynthesizing the aldehyde.
- Ibrahim, Malek Y. S.,Denmark, Scott E.
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p. 10362 - 10367
(2018/07/31)
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- Palladium-Catalysed Construction of All-Carbon Quaternary Centres with Propargylic Electrophiles: Challenges in the Simultaneous Control of Regio-, Chemo- and Enantioselectivity
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This article describes the palladium-catalysed three-component coupling of 1,3-dicarbonyl compounds with nucleophiles and propargylic electrophiles for the generation of quaternary all-carbon centres in a single step, which necessitates the simultaneous control of regio-, chemo- and enantioselectivity. The use of propargyl enol carbonates, the source of two of the components, was found to be essential in maintaining high levels of regiocontrol and chemoselectivity, whereas a careful analysis of p K a trends of O-, C- and N-nucleophiles as the other coupling partner indicates that the highest levels of selectivity are likely to be obtained with relatively acidic species, such as phenols, 1,3-dicarbonyl compounds and aromatic N-heterocycles. Finally, studies towards the development of the catalytic enantioselective construction of quaternary all-carbon centres by means of alkenylation and allylic alkylation are disclosed.
- Kenny, Miles,Schr?der, Sybrin P.,Taylor, Nicholas J.,Jackson, Paula,Kitson, Daniel J.,Franckevi?ius, Vilius
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p. 1796 - 1814
(2018/04/05)
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- Base-catalyzed cross coupling of secondary alcohols and aryl-aldehydes with concomitant oxidation of alcohols to ketones: An alternative route for synthesis of the Claisen-Schmidt condensation products
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Base-catalyzed C–C cross coupling of secondary alcohols and aryl-aldehydes was achieved, when an alcoholic solution of an aryl-aldehyde was stirred under reflux for 45?h in the presence of a catalytic (20?mol%) amount of K2CO3. The consistent formation of α,α′-bis-(benzylidene) alkanones was obtained in moderate to good yields using various secondary alcohols and substituted aryl-aldehydes. Herein, α,α′-bis-(benzylidene)alkanones, which are the classical products of Claisen-Schmidt (cross aldol) condensation, have been synthesized via an alternative strategy using secondary alcohols. Bis-(benzylidene) alkanones are an integral part of various drug regimes and the production of bis-(benzylidene) alkanones without using any precious metal is a major outcome of the present reaction.
- Satrawala, Naveen,Sharma, Kamal N.,Matsinha, Leah C.,Maqeda, Latisa,Siangwata, Shepherd,Smith, Gregory S.,Joshi, Raj K.
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supporting information
p. 2761 - 2764
(2017/06/23)
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- Supported palladium nanoparticles as switchable catalyst for aldehyde conjugate/s and acetate ester syntheses from alcohols
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Polymer-supported Pd(0) (Pd@PS) nanoparticles (NPs) were explored as a switchable catalyst for oxidative aldehyde conjugate/s (AC/s) and acetate esters (AEs) syntheses from alcohols. Using the same substrates, the catalyst in the presence of oxygen and K2CO3 participated in AC/s synthesis, and in the presence of traces of air and NaOtBu, unusual AEs products were obtained.
- Kumar, Sandeep,Chaudhary, Abha,Bandna,Bhattacherjee, Dhananjay,Thakur, Vandna,Das, Pralay
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p. 3242 - 3245
(2017/07/12)
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- Direct Regioselective [3 + 2]-Cyclization Reactions of Ambivalent Electrophilic/Nucleophilic β-Chlorovinyl Dithianes: Access to Cyclopentene Derivatives
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The highly regioselective and operationally straightforward [3 + 2] cyclizations of β-chlorovinyl dithianes with α,β-unsaturated carbonyl compounds have been developed. This protocol provides direct access to highly functionalized cyclopentenes with perfect chemo- and regioselectivities under extremely mild reaction conditions. In particular, the unprecedented cyclization allows for the selective preparation of hydroxylated cyclopentenes.
- Liang, Yongping,Lai, Junshan,Liu, Teng,Tang, Shouchu
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supporting information
p. 5086 - 5089
(2016/10/14)
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- Chemoselective Claisen-Schmidt bis-substitutional condensation catalyzed by an alkoxy-bridged dinuclear Ti(IV) cluster
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The highly efficient and chemoselective α,α′-bis-substitution of alkanones is important in organic synthesis. Herein, a dimeric titanium cluster, Ti2Cl2(OPri)6·2HOPri (Ti2), is used in the Claisen-Schmidt condensation reaction, for the selectively activation of symmetrical ketones containing α,α′-methylene groups and production of α,α′-bis-substituted alkanones in high efficiency and chemoselectivity. The high efficiency and chemoselectivity can be extended to a variety of typical alkanones and aromatic aldehydes. Both of the oxo-bridged dimeric motif of Ti2 and the ionic Ti-Cl bond are responsible for the high efficiency and chemoselectivity.
- Wu, Yufei,Hou, Jie,Liu, Yuliang,Zhang, Mingfu,Tung, Chen-Ho,Wang, Yifeng
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p. 1511 - 1516
(2016/03/01)
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- The cascade synthesis of α,β-unsaturated ketones via oxidative C-C coupling of ketones and primary alcohols over a ceria catalyst
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We herein report the oxidative C-C coupling of ketones and primary alcohols to produce α,β-unsaturated ketones in the absence of base additives. This cascade synthetic reaction was conducted at 150 °C in 12 h using a heterogeneous CeO2 catalyst. The conversion of acetophenone reached 74% with 89% selectivity to chalcone. A correlation between the CeO2 crystal plane and catalytic performance is established as the catalytic activities decrease in the sequence of (110) > (111) > (100). Characterization using Raman spectroscopy, CO2 temperature-programmed desorption (CO2-TPD), and in situ active site-capping tests has shown that the unusual catalysis of the CeO2 catalyst is attributed to the coexistence of basic and redox active sites. These sites synergistically catalyze the oxidation of alcohols to aldehydes and the aldol condensation to ketones. Moreover, the CeO2 catalyst can be reused several times after calcination to remove the surface-adsorbed substances.
- Zhang, Zhixin,Wang, Yehong,Wang, Min,Lu, Jianmin,Zhang, Chaofeng,Li, Lihua,Jiang, Jingyang,Wang, Feng
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p. 1693 - 1700
(2016/04/05)
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- Synthesis, Isomerization, and Catalytic Transfer Hydrogenation Activity of Rhodium(III) Complexes Containing Both Chelating Dicarbenes and Diphosphine Ligands
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Different rhodium(III) complexes [Rh(C,C)(P,P)X2]+ bearing both a cis-chelating dicarbene and a diphosphine ligand were synthesized (C,C = methylene(4,4′-diimidazolylidene); P,P = 1,2-bis(diphenylphosphino)ethane (dppe), (R)-(+)-2,2′-bis(diphenylphosphino)-1,1′-binaphthalene (R-BINAP); X = halide, carbanion, NCMe). Solution analysis by NMR spectroscopy indicate a dynamic behavior of the complexes and cis/trans isomerization processes, likely through dissociation of the nonchelating ligands X (X = halide, NCMe), and eventually also involving the diphosphine ligand, identified by the formation of phosphine oxides. The presence of a diphosphine ligand in addition to the dicarbene substantially enhances the catalytic activity of the rhodium center in the transfer hydrogenation of ketones in iPrOH/KOH, reaching over 4000 turnover numbers and turnover frequencies around 1000 h-1 vs 330 h-1 for the phosphine-free analogue. Optimization of the catalytic conditions allowed transfer hydrogenation to be run with only 1 mol % base instead of the often used 10 mol %. The chiral R-BINAP ligand enhances catalytic activity, though no enantioselectivity was induced in the transfer hydrogenation of fluoroacetophenone as prochiral substrate.
- Farrell, Kevin,Müller-Bunz, Helge,Albrecht, Martin
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p. 5723 - 5733
(2016/01/12)
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- Iron-catalyzed aerobic oxidative aromatization of 1,3,5-trisubstituted pyrazolines
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A simple and high yielding method for the synthesis of tri-substituted pyrazoles via iron(III) catalyzed aerobic oxidative aromatization of pyrazolines has been reported. The process demonstrates a variety of functional group tolerance.
- Ananthnag, Guddekoppa S.,Adhikari, Adithya,Balakrishna, Maravanji S.
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p. 240 - 243
(2013/12/04)
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- A novel transition metal-free conjugate reduction of α,β-unsaturated ketones with tosylhydrazine as a hydrogen source
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A novel and efficient method has been developed for the chemoselective conjugate reduction of α,β-unsaturated ketones with tosylhydrazine as a hydrogen source to the corresponding saturated ketones in moderate to good yields. The present protocol does not require the use of transition metal, and is efficient being applicable to a wide range of substrates (25 examples).
- Zhou, Xiaomeng,Li, Xiaokang,Zhang, Wei,Chen, Junmin
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supporting information
p. 5137 - 5140
(2015/02/19)
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- Functionalized curcumin analogs as potent modulators of the Wnt/β-catenin signaling pathway
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Osteosarcoma is a primary bone malignancy with aggressive metastatic potential and poor prognosis rates. In our earlier work we have investigated the therapeutic potential of curcumin as an anti-invasive agent in osteosarcoma by its ability to regulate the Wnt/β-catenin signaling pathway. However, the clinical use of curcumin is limited owing to its low potency and poor pharmacokinetic profile. In this study, an attempt was made to achieve more potent Wnt inhibitory activity in osteosarcoma cells by carrying out synthetic chemical modifications of curcumin. We synthesized a total of five series consisting of 43 curcumin analogs and screened in HEK293T cells for inhibition of β-catenin transcriptional activity. Six promising analogs, which were 6.5- to 60-fold more potent than curcumin in inhibiting Wnt activity, were further assessed for their anti-invasive activity and Wnt inhibitory mechanisms. Western blot analysis showed disruption of β-catenin protein nuclear translocation following treatment with analogs 2f, 3c and 4f. Using transwell assays, we also found that these compounds were more potent than 1a (curcumin) in impeding the invasion of osteosarcoma cells, possibly through suppressing MMP-9 activity. Structure-activity-relationship studies revealed that Wnt inhibitory effects could be enhanced by shortening and restraining the flexibility of the 7-carbon linker moiety connecting the terminal aromatic rings of curcumin and substituting both rings with appropriate substituents. Our results demonstrate that the synthesized curcumin analogs are more potent Wnt inhibitors in osteosarcoma cell lines as compared to parental curcumin and are good lead compounds for further development. Future in vivo tests with these compounds will define their therapeutic potentials as promising drug candidates for clinical treatment of osteosarcoma.
- Leow, Pay-Chin,Bahety, Priti,Boon, Choon Pei,Lee, Chong Yew,Tan, Kheng Lin,Yang, Tianming,Ee, Pui-Lai Rachel
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- Spectral characterization and crystal structure of some 2,6-diarylthian-4-one hydrazone derivatives
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A series of cis and trans 2,6-diarylthian-4-one hydrazone derivatives (11-16) have been synthesized and characterized by 1H, 13C and two dimensional NMR spectroscopy. For the 2r,6t-diphenylthian-4-one N-isonicotinoylhydrazone (14) X-ray diffraction have also been recorded. The coupling constants suggested that the cis-hydrazones (11-13), which have the phenyl groups in cis orientation, largely exist in chair conformations with equatorial orientation of the phenyl groups 11C. Analysis of the vicinal coupling constants of trans-hydrazones (14-16) suggests that boat forms 14B must make significant contributions to it and the relative population is 58%. Moreover, in solution chair conformations 14C and 14C′, may contribute to 14. The NOESY and X-ray diffraction of 14 gives definite evidence for the contribution of 14C.
- Sankar,Umamatheswari,Pandiarajan
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p. 554 - 563
(2015/01/08)
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- Oxygen as single oxidant for two steps: Base-free one-pot Pd(ii)-catalyzed alcohol oxidation & arylation to halogen-intact β-aryl α,β-enones
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Using oxygen as the sole oxidant for two steps, we developed a new method to synthesize β-aryl α,β-enones by fine-tuning the Pd(ii)-catalyzed oxidation of allyl alcohol to subsequent arylation with arylboronic acids, arylboronic ester and aryltrifluoroborate salt. This one-pot green method does not require copper salt, base, and intermediate isolation. Halogen-bearing chalcones, dibenzylideneacetones and arylalkyl enones were synthesized in good yields. This journal is
- Vellakkaran, Mari,Andappan, Murugaiah M. S.,Nagaiah, Kommu
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p. 45490 - 45494
(2014/12/10)
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- Synthesis and catalytic alcohol oxidation and ketone transfer hydrogenation activity of donor-functionalized mesoionic triazolylidene ruthenium(ii) complexes
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We report on the synthesis of a variety of C,E-bidentate triazolylidene ruthenium complexes that comprise different donor substituents E (E = C: phenyl anion; E = O: carboxylate, alkoxide; E = N: pyridine at heterocyclic carbon or nitrogen). Introduction of these donor functionalities is greatly facilitated by the synthetic versatility of triazoles, and their facile preparation routes. Five different complexes featuring a C,E-coordinated ruthenium center with chloride/cymene spectator ligands and three analogous solvento complexes with MeCN spectator ligands were prepared and evaluated as catalyst precursors for direct base- and oxidant-free alcohol dehydrogenation, and for transfer hydrogenation using basic iPrOH as a source of dihydrogen. In both catalytic reactions, the neutral/mono-cationic complexes with chloride/cymene spectator ligands performed better than the solvento ruthenium complexes. The donor functionality had a further profound impact on catalytic activity. For alcohol dehydrogenation, the C,C-bidentate phenyl-triazolylidene ligand induced highest conversions, while carboxylate or pyridine donor sites gave only moderate activity or none at all. In contrast, transfer hydrogenation is most efficient when a pyridyl donor group is linked to the triazolylidene via the heterocyclic carbon atom, providing turnover frequencies as high as 1400 h-1 for cyclohexanone transfer hydrogenation. The role of the donor group is discussed in mechanistic terms.
- Delgado-Rebollo, Manuela,Canseco-Gonzalez, Daniel,Hollering, Manuela,Mueller-Bunz, Helge,Albrecht, Martin
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p. 4462 - 4473
(2014/03/21)
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- Penta- and decafluorinated dibenzalacetones: Synthesis, crystal structure, and cocrystallization experiments
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The nonfluorinated parent dibenzalacetone 1 as well as the corresponding penta- (2) and decafluorinated (3) derivative compounds were prepared, crystallized, and subjected to co-crystallization experiments. Only 3 yielded a 1:1 co-crystal with 1, while 2 did not form co-crystals with either 1 or 3. Powder X-ray diffraction patterns were determined to verify the co-crystallization experiments. The influence of the fluorine on the molecular geometry and crystal packing were studied and comparatively discussed. Conclusions with reference to the priority of Ar...ArF contact modes in the crystalline packing being in competition with other fluorine and non-fluorine involved supramolecular interactions were drawn.
- Schwarzer, Anke,Weber, Edwin
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p. 2335 - 2342
(2014/05/20)
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- Efficient synthesis of trifluoromethylated cyclopentadienes/fulvenes/ norbornenes from divinyl ketones
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The synthetic methods of trifluoromethylated cyclopentadienes/fulvenes/ norbornenes have been developed using 3-CF3-1,4-dien-3-ols as the synthons, which can be easily prepared by the regiospecific 1,2-addition of the Ruppert-Prakash reagent (TMSCF3) to divinyl ketones. All the reactions are carried out under mild, metal-free conditions to afford the corresponding products in high to excellent yields.
- Liu, Xiao,Xu, Xianxiu,Pan, Ling,Zhang, Qian,Liu, Qun
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supporting information
p. 6703 - 6706
(2013/10/01)
-
- Inhibitory effect of curcumin analogs on tissue factor procoagulant activity and their preliminary structure-activity relationships
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With the aim to explore the multifunctional behaviors of curcumin analogs and to discover new small molecular tissue factor inhibitors, twelve mono carbonyl curcumin analogs of three classes were synthesized and their effect on tissue factor procoagulant activity was evaluated in the human monoblastic leukemia THP-1 cells stimulated by LPS. The most potent compounds 2a exhibited the dramatically enhanced activity with the IC50 values of 0.053 nM. Their preliminary structure-activity relationship was also discussed.
- Ge, Hai-Xia,Chen, Ling,Zhang, Jian,Kou, Jun-Ping,Yu, Bo-Yang
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p. 3242 - 3246
(2013/07/27)
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- Copper-catalyzed rearrangement of N-aryl nitrones into epoxyketimines
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Please pass the oxygen: A new method for the preparation of trans-α,β-epoxyketimines has been achieved through a copper-catalyzed rearrangement of (E)-α,β-unsaturated nitrones. The scope and tolerance of the method is evaluated and the synthetic utility of the products is demonstrated. The new transformation provides facile access to an unusual, densely functionalized intermediate that can be exploited for further synthetic application. Copyright
- Mo, Dong-Liang,Anderson, Laura L.
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supporting information
p. 6722 - 6725
(2013/07/26)
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- Synthesis of both kinetically and thermodynamically controlled diastereomeric pairs of bis-isoxazolidines from dibenzylideneacetone: Their reactivity and biological activity
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Reactions of C-aryl-N-phenyl-nitrones with dibenzylideneacetone yielded pairs of diastereomeric bis-isoxazolidines in good to moderate yields. Both types of cycloadducts possessed identical regio- and stereo-selectivity. Molecular modeling studies revealed small difference in energy between the two isomers. Less stable isomer was converted to more stable one via partial cycloreversion followed by re-cycloaddition pathway. Zinc mediated acid catalyzed cycloreversion was observed for more stable diastereomer whereas less stable one yielded corresponding bis-1,3-aminoalcohols in similar condition. Some cycloadducts were screened for anticancer and antibacterial activity.
- Bhattacharyya, Bhaswati,Kundu, Arijit,Dhara, Kaliprasanna,Guchhait, Nikhil,Pal, Bijan K.,Hazra, Sudipta,Debnath, Sukalyani,Hazra, Banasri,Patra, Amarendra
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p. 1447 - 1459
(2014/01/17)
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- Aldol reactions mediated by a tetrahedral boronate
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The base is a key factor in aldol reactions in organic media, determining the selectivity. Here, we describe a tetrahedral phenylboronate salt as a mild non-nucleophilic base that is able to catalyse the aldol reaction and significantly decrease the formation of undesired elimination products. This journal is
- Mueller, Tobias,Djanashvili, Kristina,Arends, Isabel W.C.E.,Peters, Joop A.,Hanefeld, Ulf
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supporting information
p. 361 - 363
(2013/02/23)
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- Synthesis of 2-(1,5-diaryl-1,4-pentadien-3-ylidene)- hydrazinecarboximidamide hydrochloride catalyzed by p-dodecylbenzenesulfonic acid in aqueous media under ultrasound irradiation
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Amidinohydrazone compounds are very important synthetic intermediates and can serve as versatile precursors in synthesis of many natural products and drug molecules. The use of ultrasound, p-dodecylbenzenesulfonic acid (DBSA) and water as solvent improved the synthesis of different 2-(1,5-diaryl-1,4- pentadien-3-ylidene)-hydrazinecarboximidamide hydrochlorides. The best reaction conditions for the condensation of 1,5-diphenyl-1,4-pentadien-3-one with aminoguanidine hydrochloride were as follows: 1,5-diphenyl-1,4-pentadiene-3-one (1, 1 mmol), aminoguanidine hydrochloride (1.1 mmol), DBSA (0.5 mmol), water 10 mL, reaction temperature 25-27°C, irradiation frequency 25 kHz. 2a was achieved in 94% yield within 2 h. The other seven amidinohydrazones were obtained in 84-94% yield within 2-3 h under the same conditions. Compared to the method involving catalysis by hydrochloric acid in refluxing EtOH, the advantages of present procedure are milder conditions, shorter reaction times, higher yields, and environmental friendly conditions, which make it a useful strategy for the synthesis of analogues.
- Li, Ji-Tai,Du, Chao,Xu, Xiao-Ya,Chen, Guo-Fen
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experimental part
p. 1033 - 1038
(2012/07/03)
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- Cu(OAc)2/TFA-promoted formal [3 + 3] cycloaddition/oxidation of enamines and enones for synthesis of multisubstituted aromatic amines
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New strategies for the oxidative cycloaddition of enones with enamines are developed. These cycloaddition reactions directly afford substituted aromatic amines, which are important in organic chemistry, in moderate to good yield. Cu(OAc)2/TFA is shown to be essential to achieve high reaction efficiency.
- Li, Liang,Zhao, Mi-Na,Ren, Zhi-Hui,Li, Jian-Li,Guan, Zheng-Hui
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supporting information; experimental part
p. 3506 - 3509
(2012/08/08)
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- Novel one-pot three-component coupling reaction with trimethylsilylmethyl- phosphonate, acyl fluoride, and aldehyde through the horner-wadsworth-emmons reaction
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A novel three-component coupling between trimethylsilylmethylphosphonate, acyl fluoride, and aldehyde has been developed. A sequential nucleophilic addition of lithio-trimethylsilylmethylphosphonate to the acyl fluoride and Horner-Wadsworth-Emmons reaction of an aldehyde with the lithio-β- ketophosphonate generated in situ by desilylation at the α-position of the α-silyl-β-ketophosphonate by fluoride took place cleanly in a one-pot operation. Various E- and Z-enones were obtained in high yields with high stereoselectivities by this one-pot procedure.
- Umezawa, Taiki,Seino, Tomoya,Matsuda, Fuyuhiko
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experimental part
p. 4206 - 4209
(2012/09/25)
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- Phosphine-catalyzed cascade [3 + 2] cyclization-allylic alkylation, [2 + 2 + 1] annulation, and [3 + 2] cyclization reactions between allylic carbonates and enones
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The phosphine-catalyzed annulations between Morita-Baylis-Hillman adduct carbonates and enones are reported. Under the catalysis of PBu3 (20 mol %), cascade [3 + 2] cyclization-allylic alkylation, [2 + 2 + 1] annulation, and [3 + 2] cyclization reactions chemoselectively occur depending on the substituent variation of both the carbonate and enone. These reactions provide efficient syntheses of highly functionalized cyclopentenes and cyclopentanes.
- Zhou, Rong,Wang, Jianfang,Song, Haibin,He, Zhengjie
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supporting information; scheme or table
p. 580 - 583
(2011/04/23)
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- 1,5,7-Triazabicyclo[4.4.0]dec-5-ene (TBD) an efficient homogeneous catalyst for aldol condensation reactions. Study of the catalyst recovery and reusability using CO2
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In this work it was shown that TBD (1,5,7-triazabicyclo[4.4.0]dec-5-ene), a cheap and commercially available guanidine base, efficiently catalyzes aldol condensation reactions yielding interesting products for pharmacological and fragrance industries. This methodology works under solvent-less conditions and affords with very good conversions the corresponding products. Moreover, a simple and effective separation protocol using the CO2 fixation was employed. The catalyst could be recovered and re-used for three consecutive runs without significant loss of activity.
- Cota, Iuliana,Medina, Francisco,Sueiras, Jesús E.,Tichit, Didier
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experimental part
p. 385 - 387
(2011/02/28)
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- Novel and efficient one pot condensation reactions between ketones and aromatic alcohols in the presence of CrO3 producing α,β-unsaturated carbonyl compounds
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We report a new, effective and simple method for preparing α,β-unsaturated carbonyl compounds by reacting ketones and aromatic alcohols at 56 °C in the presence of CrO3 (CrO3 acts as an oxidant and also a catalyst) for around 10 h. The condensation reactions occurred effectively among a wide combination of ketones and alcohols. The procedure is simple and the yields can be high up to 98%. And a probable mechanism is proposed.
- Li, Yanan,Chen, Daoyong
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body text
p. 2086 - 2090
(2012/04/04)
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