- Synthesis of [6,6,m]-Tricyclic Compounds via [4+2] Cycloaddition with Au or Cu Catalyst
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We synthesized [6,6,6]- and [6,6,7]-tricyclic compounds via intramolecular [4+2] cycloaddition by gold or copper catalysts. Substrates for cyclization were prepared by coupling reactions between eight types of diyne and four types of aromatic moieties. We have successfully synthesized eleven tricyclic compounds.
- Kang, Juyeon,Ham, Seunghwan,Seong, Chaehyeon,Oh, Chang Ho
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supporting information
p. 1039 - 1043
(2021/05/05)
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- Stereoselective Total Synthesis of (-)-(2 S,4 R)-3′-Methoxyl Citreochlorol: Preparation and Use of New Proline-Based Auxiliary for Asymmetric Acetate Aldol Reaction
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The first stereoselective total synthesis of (-)-(2S,4R)-3′-methoxy citreochlorol and (-)-(2S,4S)-3′-methoxy citreochlorol is demonstrated. A proline-based imidazolidinone was synthesized and used as chiral auxiliary for asymmetric acetate aldol reaction to generate initial chirality in the targeted molecule. Geminal dichloromethane functionality was introduced by the addition of in situ generated dichloromethyllithium to Weinreb's amide functional group.
- Sunnapu, Ranganayakulu,Banoth, Saikumar Naik,Reyno,Thomas, Aleena,Venugopal, Navyasree,Rajendar, Goreti
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p. 4103 - 4113
(2020/03/05)
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- 4-Methyltetrahydropyran (4-MeTHP): Application as an Organic Reaction Solvent
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4-Methyltetrahydropyran (4-MeTHP) is a hydrophobic cyclic ether with potential for industrial applications. We herein report, for the first time, a comprehensive study on the performance of 4-MeTHP as an organic reaction solvent. Its broad application to organic reactions includes radical, Grignard, Wittig, organometallic, halogen-metal exchange, reduction, oxidation, epoxidation, amidation, esterification, metathesis, and other miscellaneous organic reactions. This breadth suggests 4-MeTHP can serve as a substitute for conventional ethers and harmful halogenated solvents. However, 4-MeTHP was found incompatible with strong Lewis acids, and the C?O bond was readily cleaved by treatment with BBr3. Moreover, the radical-based degradation pathways of 4-MeTHP, THP and 2-MeTHF were elucidated on the basis of GC-MS analyses. The data reported herein is anticipated to be useful for a broad range of synthetic chemists, especially industrial process chemists, when selecting the reaction solvent with green chemistry perspectives.
- Kobayashi, Shoji,Tamura, Tomoki,Yoshimoto, Saki,Kawakami, Takashi,Masuyama, Araki
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p. 3921 - 3937
(2019/11/11)
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- Studies toward the synthesis of caramboxin analogues
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Intrigued by the recent discovery of caramboxin by Brazilian researchers, we present the results from our studies toward the racemic synthesis of caramboxin analogs through the ortho-carboxylation of 3,5-dimethoxy benzyl derivatives. Three different approaches were tested, and the route involving a Vilsmeier-Haack formylation followed by a Lindgren oxidation provide a potential intermediate for the synthesis of several caramboxin analogs.
- Oliveira Filho, Ronaldo E.,Higa, Vanessa M.,Omori, álvaro T.
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p. 528 - 540
(2019/08/26)
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- Prenylated Stilbenoids Affect Inflammation by Inhibiting the NF-κB/AP-1 Signaling Pathway and Cyclooxygenases and Lipoxygenase
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Stilbenoids are important components of foods (e.g., peanuts, grapes, various edible berries), beverages (wine, white tea), and medicinal plants. Many publications have described the anti-inflammatory potential of stilbenoids, including the widely known trans-resveratrol and its analogues. However, comparatively little information is available regarding the activity of their prenylated derivatives. One new prenylated stilbenoid (2) was isolated from Artocarpus altilis and characterized structurally based on 1D and 2D NMR analysis and HRMS. Three other prenylated stilbenoids were prepared synthetically (9-11). Their antiphlogistic potential was determined by testing them together with known natural prenylated stilbenoids from Macaranga siamensis and Artocarpus heterophyllus in both cell-free and cell assays. The inhibition of 5-lipoxygenase (5-LOX) was also shown by simulated molecular docking for the most active stilbenoids in order to elucidate the mode of interaction between these compounds and the enzyme. Their effects on the pro-inflammatory nuclear factor-κB (NF-κB) and the activator protein 1 (AP-1) signaling pathway were also analyzed. The THP1-XBlue-MD2-CD14 cell line was used as a model for determining their anti-inflammatory potential, and lipopolysaccharide (LPS) stimulation of Toll-like receptor 4 induced a signaling cascade leading to the activation of NF-κB/AP-1. The ability of prenylated stilbenoids to attenuate the production of pro-inflammatory cytokines tumor necrosis factor-α (TNF-α) and interleukin-1β (IL-1β) was further evaluated using LPS-stimulated THP-1 macrophages.
- Ho?ek, Jan,Leláková, Veronika,Bobál, Pavel,Pí?ová, Hana,Gazdová, Markéta,Malaník, Milan,Jakubczyk, Karolina,Vesely, Ond?ej,Landa, P?emysl,Temml, Veronika,Schuster, Daniela,Prachyawarakorn, Vilailak,Pailee, Phanruethai,Ren, Gang,Zpurny, Filip,Oravec, Michal,?mejkal, Karel
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p. 1839 - 1848
(2019/08/20)
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- Parallel in vitro and in silico investigations into anti-inflammatory effects of non-prenylated stilbenoids
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Stilbenoids represent a large group of bioactive compounds, which occur in food and medicinal plants. Twenty-five stilbenoids were screened in vitro for their ability to inhibit COX-1, COX-2 and 5-LOX. Piceatannol and pinostilbene showed activity comparable to the zileuton and ibuprofen, respectively. The anti-inflammatory potential of stilbenoids was further evaluated using THP-1 human monocytic leukemia cell line. Tests of the cytotoxicity on the THP-1 and HCT116 cell lines showed very low toxic effects. The tested stilbenoids were evaluated for their ability to attenuate the LPS-stimulated activation of NF-κB/AP-1. Most of the tested substances reduced the activity of NF-κB/AP-1 and later attenuated the expression of TNF-α. The effects of selected stilbenoids were further investigated on inflammatory signaling pathways. Non-prenylated stilbenoids regulated attenuation of NF-?B/AP-1 activity upstream by inhibiting the phosphorylation of MAPKs. A docking study used to in silico analyze the tested compounds confirmed their interaction with NF-?B, COX-2 and 5-LOX.
- Leláková, Veronika,?mejkal, Karel,Jakubczyk, Karolina,Vesely, Ond?ej,Landa, P?emysl,Václavík, Ji?í,Bobá?, Pavel,Pí?ová, Hana,Temml, Veronika,Steinacher, Theresa,Schuster, Daniela,Granica, Sebastian,Hanáková, Zuzana,Ho?ek, Jan
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p. 431 - 440
(2019/02/19)
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- Stereoselective synthesis of 5′-hydroxyzearalenone
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A first stereoselective total synthesis of 14-memebered β-resorcylic macrolactone 5′-hydroxyzearalenone (1) has been achieved. The key steps are Jocobsen hydrolytic kinetic resolution, Sharpless asymmetric dihydroxylation, Vilsmeier-Haack reaction, Mitsunobu esterification and ring-closing metathesis.
- Avuluri, Srilatha,Bujaranipalli, Sheshurao,Das, Saibal,Yadav
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supporting information
p. 3547 - 3549
(2018/08/29)
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- Assessment of the regioselectivity in the condensation reaction of unsymmetrical o-phthaldialdehydes with alanine
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One approach for the synthesis of isoindolinones, a privileged bioactive heterocyclic core structure, involves a condensation reaction of o-phthaldialdehydes with a suitable nitrogen-containing nucleophile. This fascinating reaction is revisited here in the context of the use of o-phthaldialdehydes that contain additional substituents in the aromatic ring leading to a detailed analysis of the regioselectivity of the reaction. Eleven monosubstituted o-phthaldialdehydes were synthesised and reacted with alanine. The regioselectivity observed across the eleven substrates led to the design of a disubstituted substrate that reacted with very high control. A gram-scale reaction followed by esterification gave one major regioisomer in high yield. In addition, the regioselectivity observed on reaction of two novel monodeuterated substrates led to an increased mechanistic understanding.
- D'Hollander, Agathe C.A.,Westwood, Nicholas J.
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supporting information
p. 224 - 239
(2017/12/08)
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- A concise approach to anthraquinone-xanthone heterodimers
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A synthetic approach to anthraquinone-xanthone heterodimers is described. The route to the pentacyclic core features an efficient assembly of a benzocycloheptenone via a new intramolecular oxidative arylation of an enol ether and a Hauser-Kraus annulation-aldol reaction sequence to access the characteristic bicyclo[3.2.2]nonene motif. Acremoxanthone A is synthesized in 10 steps from commercially available material to demonstrate the application of this approach.
- Holmbo, Stephen D.,Pronin, Sergey V.
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supporting information
p. 5065 - 5068
(2018/04/24)
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- Methanol as hydrogen source: Transfer hydrogenation of aromatic aldehydes with a rhodacycle
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A cyclometalated rhodium complex has been shown to perform highly selective and efficient reduction of aldehydes, deriving the hydrogen from methanol. With methanol as both the solvent and hydrogen donor under mild conditions and an open atmosphere, a wide range of aromatic aldehydes were reduced to the corresponding alcohols, without affecting other functional groups.
- Aboo, Ahmed H.,Bennett, Elliot L.,Deeprose, Mark,Robertson, Craig M.,Iggo, Jonathan A.,Xiao, Jianliang
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supporting information
p. 11805 - 11808
(2018/11/10)
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- Discovery of boron-containing compounds as Aβ aggregation inhibitors and antioxidants for the treatment of Alzheimer's disease
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A novel series of boron-containing compounds were designed, synthesized and evaluated as multi-target-directed ligands against Alzheimer's disease. The biological activity results demonstrated that these compounds possessed a significant ability to inhibit self-induced Aβ aggregation (20.5-82.8%, 20 μM) and to act as potential antioxidants (oxygen radical absorbance capacity assay using fluorescein (ORAC-FL) values of 2.70-5.87). In particular, compound 17h is a potential lead compound for AD therapy (IC50 = 3.41 μM for self-induced Aβ aggregation; ORAC-FL value = 4.55). Compound 17h also functions as a metal chelator. These results indicated that boron-containing compounds could be new structural scaffolds for the treatment of AD.
- Lu, Chuan-Jun,Hu, Jinhui,Wang, Zechen,Xie, Shishun,Pan, Tingting,Huang, Ling,Li, Xingshu
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p. 1862 - 1870
(2018/11/24)
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- Sea Urchin Embryo Model As a Reliable in Vivo Phenotypic Screen to Characterize Selective Antimitotic Molecules. Comparative evaluation of Combretapyrazoles, -isoxazoles, -1,2,3-triazoles, and -pyrroles as Tubulin-Binding Agents
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A series of both novel and reported combretastatin analogues, including diarylpyrazoles, -isoxazoles, -1,2,3-triazoles, and -pyrroles, were synthesized via improved protocols to evaluate their antimitotic antitubulin activity using in vivo sea urchin embryo assay and a panel of human cancer cells. A systematic comparative structure-activity relationship studies of these compounds were conducted. Pyrazoles 1i and 1p, isoxazole 3a, and triazole 7b were found to be the most potent antimitotics across all tested compounds causing cleavage alteration of the sea urchin embryo at 1, 0.25, 1, and 0.5 nM, respectively. These agents exhibited comparable cytotoxicity against human cancer cells. Structure-activity relationship studies revealed that compounds substituted with 3,4,5-trimethoxyphenyl ring A and 4-methoxyphenyl ring B displayed the highest activity. 3-Hydroxy group in the ring B was essential for the antiproliferative activity in the diarylisoxazole series, whereas it was not required for potency of diarylpyrazoles. Isoxazoles 3 with 3,4,5-trimethoxy-substituted ring A and 3-hydroxy-4-methoxy-substituted ring B were more active than the respective pyrazoles 1. Of the azoles substituted with the same set of other aryl pharmacophores, diarylpyrazoles 1, 4,5-diarylisoxazoles 3, and 4,5-diaryl-1,2,3-triazoles 7 displayed similar strongest antimitotic antitubulin effect followed by 3,4-diarylisoxazoles 5, 1,5-diaryl-1,2,3-triazoles 8, and pyrroles 10 that showed the lowest activity. Introduction of the amino group into the heterocyclic core decreased the antimitotic antitubulin effect of pyrazoles, triazoles, and to a lesser degree of 4,5-diarylisoxazoles, whereas potency of the respective 3,4-diarylisoxazoles was increased.
- Semenova, Marina N.,Demchuk, Dmitry V.,Tsyganov, Dmitry V.,Chernysheva, Natalia B.,Samet, Alexander V.,Silyanova, Eugenia A.,Kislyi, Victor P.,Maksimenko, Anna S.,Varakutin, Alexander E.,Konyushkin, Leonid D.,Raihstat, Mikhail M.,Kiselyov, Alex S.,Semenov, Victor V.
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p. 700 - 721
(2019/01/03)
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- A facile, efficient and chemoseletive deprotection of silyl ethers using zinc (II) trifluoromethanesulfonate
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Background: A number of protective groups for hydroxyl functional groups have been developed to date. Alcohols are most commonly protected as ethers and esters, where in alkyl and benzyl ethers are strong protective groups while others, like THP, TBS, TPS and MEM/MOM ethers are acid labile. Among all other hydroxyl protecting groups, Silyl ethers are the most frequently used protecting groups because they are easily and efficiently installed and are stable to a variety of useful reagents and reaction conditions. Among the silyl ethers, triethylsilyl (TES), tert-butyldimethylsilyl (TBDMS), triisopropylsilyl (TIPS), and tert-butyldiphenylsilyl (TBDPS) moieties are the frequently used hydroxyl protecting groups in multi step organic syntheses. Methods: A mild, efficient and selective method for the deprotection of variety of silyl ethers developed in high yields by using 20 mol % of Zinc (II) trifluoromethanesulfonate (Zn(OTf)2) at room temperature in methanol as a solvent without affecting both the acid and base sensitive protecting groups was reported. Results: To study the generality of this methodology, several silyl ethers were prepared from a variety of substrates having different protecting groups and subjected to desilylation using Zn(OTf)2 in MeOH. Conclusion: In conclusion, mild and efficient protocols for the deprotection of variety of silyl ethers using 20 mol % of Zn(OTf)2 at room temperature in MeOH have been established, in which both the acid and base sensitive groups are unaffected.
- Reddy, Kotthireddy Thirumal,Sreenivasulu, Reddymasu,Veronica, Deekala,Chandrasekhar, Choragudi,Anitha, Kowthalam,Raju, Rudraraju Ramesh
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p. 191 - 195
(2018/03/09)
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- Cancerous Cell Growth Inhibiting Compounds
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The present invention provides a compound of Formula I, II or III or a salt or prodrug or derivative thereof that is useful for skin-whitening by inhibiting melanin formation and removing existing melanin and the inhibition of melanoma growth and/or the removal of existing melanoma cells.
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- Discovery and optimization of selective FGFR4 inhibitors via scaffold hopping
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Introduction of a Michael acceptor on a flexible scaffold derived from pan-FGFR inhibitors has successfully yielded a novel series of highly potent FGFR4 inhibitors with selectivity over FGFR1. Due to reduced lipophilicity and aromatic ring count, this series demonstrated improved solubility and permeability. However, plasma instability and fast metabolism limited its potential for in vivo studies. Efforts have been made to address these problems, which led to the discovery of compound (?)-11 with improved stability, CYP inhibition, and good activity/selectivity for further optimization.
- Wang, Yikai,Chen, Zhengxia,Dai, Meibi,Sun, Peipei,Wang, Chunqiu,Gao, Yang,Zhao, Haixia,Zeng, Wenqin,Shen, Liang,Mao, Weifeng,Wang, Tian,Hu, Guoping,Li, Jian,Chen, Shuhui,Long, Chaofeng,Chen, Xiaoxin,Liu, Junhua,Zhang, Yang
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supporting information
p. 2420 - 2423
(2017/05/10)
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- Preparation method for health product pterostilbene
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The invention provides a preparation method for a health product pterostilbene. According to the invention, 1, a deprotection method used in the invention is green, environment-friendly and pollution-free, the preparation method is almost free of production of waste gas, waste water and industrial residues, and the product 1,4-pentadiene has economic value; 2, a catalyst used in the invention has good cycle repeatability and can be cyclically used 50 times or more; 3, the preparation method is simple in operation requirements, mild in reaction conditions, good in specificity, simple in post-treatment and purification of the product, and suitable for industrial production; and 4, the pterostilbene prepared by using the method is free of impurities like 3-methoxy-4',5-dihydroxystilbene and resveratrol and has high purity.
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-
Paragraph 0041; 0042
(2017/12/05)
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- Solid state red biphotonic excited emission from small dipolar fluorophores
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Dyes emitting in the solid state in the red or near-infrared range are much sought after for application in bioimaging especially if the long emission wavelength can be combined with two-photon excitation to provide unique contrast and penetration depth. In this article we present a series of small push-pull dipolar fluorophores based on 2-dicyanomethylene-3-cyano-4,5,5-trimethyl-2,5-dihydrofurane as electron accepting group. Compounds 1a-1m differ only by the number (one, two or three) and the position of methoxy groups on the electron-donor part. If these compounds are weakly emissive in dilute solution, they exhibit aggregation-induced emission properties and exciting solid state emission in the red - near infrared range very different from one compound to another highlighting the role of the number and of the position of the methoxy electron-donor groups. The solid-state properties were studied by fluorescence spectroscopy and the solid state structures were analyzed by X-ray diffraction showing the presence of a long chain of specific aggregates for the emitting species. Finally, the two-photon excitation properties were measured over the range 780-920 nm directly on the solid.
- Ipuy, Martin,Liao, Yuan-Yuan,Jeanneau, Erwann,Baldeck, Patrice L.,Bretonnière, Yann,Andraud, Chantal
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p. 766 - 779
(2016/02/03)
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- Design and synthesis of a series of serine derivatives as small molecule inhibitors of the SARS coronavirus 3CL protease
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Synthesis of serine derivatives having the essential functional groups for the inhibitor of SARS 3CL protease and evaluation of their inhibitory activities using SARS 3CL R188I mutant protease are described. The lead compounds, functionalized serine derivatives, were designed based on the tetrapeptide aldehyde and Bai's cinnamoly inhibitor, and additionally performed with simulation on GOLD softwear. Structure activity relationship studies of the candidate compounds were given reasonable inhibitors ent-3 and ent-7k against SARS 3CL R188I mutant protease. These inhibitors showed protease selectivity and no cytotoxicity.
- Konno, Hiroyuki,Wakabayashi, Masaki,Takanuma, Daiki,Saito, Yota,Akaji, Kenichi
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p. 1241 - 1254
(2016/03/01)
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- Synthesis and SAR of 4-methyl-5-pentylbenzene-1,3-diol (MPBD), produced by Dictyostelium discoideum
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4-Methyl-5-pentylbenzene-1,3-diol (MPBD) is a secondary metabolite of SteelyA polyketide synthase, which controls cell aggregation and spore maturation of Dictyostelium discoideum. In this study, chemical synthesis of MPBD and its derivatives was achieved. Structure-activity relationship (SAR) studies for antimicrobial activities against Escherichia coli and Bacillus subtilis were also conducted.
- Murata, Chihiro,Ogura, Tetsuhiro,Narita, Shuhei,Kondo, Anna P.,Iwasaki, Natsumi,Saito, Tamao,Usuki, Toyonobu
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p. 1428 - 1433
(2016/02/19)
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- Cyano-containing resveratrol analogue and preparation method and purpose thereof
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The invention provides a cyano-containing resveratrol analogue and a preparation method and application thereof, and relates to the field of medical compounds. A structure of the cyano-containing resveratrol analogue is shown in the formula of the description; 3,5-dihydroxy-benzoic acid is mainly used as a raw material, and the cyano-containing resveratrol analogue is prepared by the following steps of methylation, reduction, brominating, Abozove rearrangement, Wittig-Hornor reaction and Knoevenegal reaction; in the preparation process of the cyano-containing resveratrol analogue, the chemical substances with lower toxicity, such as trimethylsilyl cyanide and tetrabutylammonium fluoride, are used for replacing chemicals with higher toxicity, such as sodium cyanide or potassium cyanide, to introduce cyano, so that the damage to the health of an operator is greatly decreased, and the serious harm to environments is avoided. The preparation method has the advantages that the yield is higher, the environment-friendly effect is good, and multiple types of cyano-containing resveratrol analogue with anti-cancer activity on cells can be obtained.
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- Synthesis of trans-resveratrol using modified Julia olefination route
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Bioactive hydroxystilbinoid-trans-resveratrol [(E)-3,5,4′ trihydroxy stilbene, 1] has been synthesized by modified Julia olefination method. The reaction between corresponding carbanion of benzothiazol-2-yl sulfone derivative and p-anisaldehyde dimethyl acetal with sodium hydride as a base, affords mainly cis-3,5,4′ trimethoxystilbene 10b with minor quantity of trans-isomev. Both the isomers have been separated in pure form and confirmed by their NMR spectral data. Demethylation of cis-3,5,4′ trimethoxystilbene either with AlCVpyridine or AlCl3/triethylamine results in the formation of trans-resveratrol.
- Shenvi, Suvarna,Shivanna, Shivaprakash,Reddy, G. Chandrasekara
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p. 1035 - 1038
(2017/11/10)
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- Synthesis and biological evaluation of novel resveratrol-oxadiazole hybrid heterocycles as potential antiproliferative agents
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A novel class of resveratrol-oxadiazole hybrid compounds was synthesized to screen for their in vitro antiproliferative activity against three human cancer cell lines. All the compounds showed superior antiproliferative activity than the reference compound resveratrol. The most promising active compounds in this series were 1g, 2g, 1c, 2c, 2i and 1a (GI50 0.1 μM), endowed with excellent antiproliferative activity. Thus, we believe that resveratrol-oxadiazole hybrid compounds may possibly be used as a good leads for the development of new antiproliferative agents. Structures of newly synthesized compounds were confirmed by NMR and IR spectral data.
- Murty,Penthala, Raju,Polepalli, Sowjanya,Jain
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p. 627 - 643
(2016/03/08)
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- Design, synthesis and antiproliferative activity of the new conjugates of E7010 and resveratrol as tubulin polymerization inhibitors
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A new class of (E)-N-phenyl-3-styrylpyridin-2-amine conjugates were designed and synthesized on the basis of E7010 and resveratrol scaffolds. These conjugates were evaluated for their antiproliferative activity in four human cancer cell lines with GI50 values ranging from 2.1 μM to 20 μM. Two of the conjugates RSV-1 and RSV-11 were found to possess 13-fold higher GI50 values than resveratrol and 1 to 2 fold higher GI50 values than E7010 against the human cervical HepG2 cancer line. They displayed high potency and selectivity in a panel of NCI 60 human cancer cell lines. Based on the GI50 values against the panel of 60 NCI cancer cell lines and dock scores from the molecular modelling studies, we selected RSV-1 and RSV-11 for tubulin polymerization and mechanistic studies. Furthermore, RSV-1 and RSV-11 compounds inhibited the assembly of tubulin by strongly binding to the colchicine-binding site. The G2/M-phase is arrested in HepG2 cells as assessed by flow cytometry. Structure based studies, western blotting and immunofluorescence experiments demonstrated that RSV-1 and RSV-11 depolymerize microtubules in the HepG2 cell line, resulting in an accumulation of G2/M cells.
- Kamal, Ahmed,Ashraf,Basha, Shaik Thokhir,Ali Hussaini,Singh, Shamshair,Vishnuvardhan,Kiran, Boppana,Sridhar, Balasubramanian
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p. 1382 - 1394
(2016/02/03)
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- Improved Catalytic Activity and Stability of a Palladium Pincer Complex by Incorporation into a Metal-Organic Framework
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A porous metal-organic framework Zr6O4(OH)4(L-PdX)3 (1-X) has been constructed from Pd diphosphinite pincer complexes ([L-PdX]4- = [(2,6-(OPAr2)2C6H3)PdX]4-, Ar = p-C6H4CO2-, X = Cl, I). Reaction of 1-X with PhI(O2CCF3)2 facilitates I-/CF3CO2- ligand exchange to generate 1-TFA and I2 as a soluble byproduct. 1-TFA is an active and recyclable catalyst for transfer hydrogenation of benzaldehydes using formic acid as a hydrogen source. In contrast, the homogeneous analogue tBu(L-PdTFA) is an ineffective catalyst owing to decomposition under the catalytic conditions, highlighting the beneficial effects of immobilization.
- Burgess, Samantha A.,Kassie, Abebu,Baranowski, Sarah A.,Fritzsching, Keith J.,Schmidt-Rohr, Klaus,Brown, Craig M.,Wade, Casey R.
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supporting information
p. 1780 - 1783
(2016/03/01)
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- Selective acetylation of primary alcohols by ethyl acetate
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A KOtBu and ethyl acetate mediated efficient methodology has been developed for the acetylation of primary and secondary alcohols where ethyl acetate is the source of acetyl group. The reaction is fast, mild, efficient, and highly selective towards the primary alcohols.
- Singha, Raju,Ray, Jayanta K.
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supporting information
p. 5395 - 5398
(2016/11/11)
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- Ruthenium Catalyzed Selective Hydroboration of Carbonyl Compounds
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Using the [Ru(p-cymene)Cl2]2 (1) complex, catalytic hydroboration of aldehydes and ketones with pinacolborane under neat and mild conditions is reported. At rt, chemoselective hydroboration of aldehydes over the ketones is also attained. Mechanistic studies confirmed the immediate formation of monohydride bridged dinuclear complex [{(μ6-p-cymene)RuCl}2(μ-H-μ-Cl)] (1b) from the reaction of 1 with pinacolborane, which catalyzed the highly efficient hydroboration reactions. The catalytic cycle containing mononuclear Ru-H species and intramolecular 1,3-hydride transfer is postulated.
- Kaithal, Akash,Chatterjee, Basujit,Gunanathan, Chidambaram
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supporting information
p. 4790 - 4793
(2015/10/12)
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- In situ activation of benzyl alcohols with XtalFluor-E: Formation of 1,1-diarylmethanes and 1,1,1-triarylmethanes through Friedel-Crafts benzylation
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The Friedel-Crafts benzylation of arenes using benzyl alcohols activated in situ with XtalFluor-E is described. A wide range of 1,1-diarylmethanes and 1,1,1-triarylmethanes were prepared under experimentally simple and mild conditions, without the need for a transition metal or a strong Lewis acid. Notably, the reactivity observed demonstrates the potential of XtalFluor-E to induce C-OH bond ionization and SN1 reactivity of benzylic alcohols. This journal is
- Desroches, Justine,Champagne, Pier Alexandre,Benhassine, Yasmine,Paquin, Jean-Franois
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supporting information
p. 2243 - 2246
(2015/03/04)
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- CATALYTIC HYDROGENATION USING COMPLEXES OF BASE METALS WITH TRIDENTATE LIGANDS
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Complexes of cobalt and nickel with tridentate ligand PNHPR are effective for hydrogenation of unsaturated compounds. Cobalt complex [(PNHPCy)Co(CH2SiMe3)]BArF4 (PNHPCy=bis[2-(dicyclohexylphosphino)ethyl]amine, BArF4=B(3,5-(CF3)2C6H3)4)) was prepared and used with hydrogen for hydrogenation of alkenes, aldehydes, ketones, and imines under mild conditions (25-60° C., 1-4 atm H2). Nickel complex [(PNHPCy)Ni(H)]BPh4 was used for hydrogenation of styrene and 1-octene under mild conditions. (PNPCy)Ni(H) was used for hydrogenating alkenes.
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Paragraph 0055; 0070
(2015/12/07)
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- Synthesis and biological evaluation of novel gigantol derivatives as potential agents in prevention of diabetic cataract
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As a continuation of our efforts directed towards the development of natural anti-diabetic cataract agents, gigantol was isolated from Herba dendrobii and was found to inhibit both aldose reductase (AR) and inducible nitric oxide synthase (iNOS) activity, which play a significant role in the development and progression of diabetic cataracts. To improve its bioefficacy and facilitate use as a therapeutic agent, gigantol (compound 14f) and a series of novel analogs were designed and synthesized. Analogs were formulated to have different substituents on the phenyl ring (compounds 4, 5, 8, 14a-e), substitute the phenyl ring with a larger steric hindrance ring (compounds 10, 17c) or modify the carbon chain (compounds 17a, 17b, 21, 23, 25). All of the analogs were tested for their effect on AR and iNOS activities and on D-galactose-induced apoptosis in cultured human lens epithelial cells. Compounds 5, 10, 14a, 14b, 14d, 14e, 14f, 17b, 17c, 23, and 25 inhibited AR activity, with IC50 values ranging from 5.02 to 288.8 μM. Compounds 5, 10, 14b, and 14f inhibited iNOS activity with IC50 ranging from 432.6 to 1188.7 μM. Compounds 5, 8, 10, 14b, 14f, and 17c protected the cells from D-galactose induced apoptosis with viability ranging from 55.2 to 76.26%. Of gigantol and its analogs, compound 10 showed the greatest bioefficacy and is warranted to be developed as a therapeutic agent for diabetic cataracts.
- Wu, Jie,Lu, Chuanjun,Li, Xue,Fang, Hua,Wan, Wencheng,Yang, Qiaohong,Sun, Xiaosheng,Wang, Meiling,Hu, Xiaohong,Chen, C.-Y. Oliver,Wei, Xiaoyong
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- Synthesis and bioactivity of resveratrol analogues
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It has been reported that resveratrol enhanced SIRT1 expression and significantly mimicked calorie restriction by stimulating Sir2 which is the most homologic homologue of SIRT1 of mammalian. A series of novel resveratrol derivatives were designed and synthesized as novel SIRT1 activator candidates. These synthesized compounds were characterized by spectral (1H NMR) analysis and examined for their Sir2 activation against yeast parental strain-BY4743 at a concentration of 100 μM/L by Bioscreen C MBR machine. Several compounds showed a promising Sir2 activation activity compared with resveratrol. Meanwhile, the structure-activity relationships with Sirt2 activation activities were also discussed.
- Ao, Junli,Chen, Yuanmou,Xu, Xiaoling,Zhang, Xu,Yu, Yue,Yu, Peng,Hua, Erbing
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p. 2092 - 2098
(2014/06/09)
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- Regioselective bromination: An approach to the D-ring of the gilvocarcins
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A method for the regioselective ortho-bromination of unsymmetrically protected 3,5-dihydroxybenzoic acid esters has been developed. The route involves protecting group optimization studies to attain high regioselectivity for the ortho-bromination. Pd-catalyzed stannation and boration were performed to construct the D-ring coupling partners for the synthesis of gilvocarcin analogs.
- Sharif, Ehesan U.,O'Doherty, George A.
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p. 1275 - 1285
(2016/11/11)
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- Chemoselective reduction of the carbonyl functionality through hydrosilylation: Integrating click catalysis with hydrosilylation in one pot
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Herein we report the chemoselective reduction of the carbonyl functionality via hydrosilylation using a copper(I) catalyst bearing the abnormal N-heterocyclic carbene 1 with low (0.25 mol %) catalyst loading at ambient temperature in excellent yield within a very short reaction time. The hydrosilylation reaction of α,β-unsaturated carbonyl compounds takes place selectively toward 1,2-addition (C=O) to yield the corresponding allyl alcohols in good yields. Moreover, when two reducible functional groups such as imine and ketone groups are present in the same molecule, this catalyst selectively reduces the ketone functionality. Further, 1 was used in a consecutive fashion by combining the Huisgen cycloaddition and hydrosilylation reactions in one pot, yielding a range of functionalized triazole substituted alcohols in excellent yields.
- Roy, Sudipta Raha,Sau, Samaresh Chandra,Mandal, Swadhin K.
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p. 9150 - 9160
(2014/12/11)
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- Palladium-catalyzed arylation of aldehydes with bromo-substituted 1,3-diaryl-imidazoline carbene ligand
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The combination of 0 valent palladium precursor and bromo-substituted 1,3-diaryl-imidazoline carbene ligand precursor such as 1-(2-bromophenyl)-3-(2,6-diisopropylphenyl)-imidazolinium chloride 1a exhibited high catalytic activity for the 1,2-addition of arylboronic acids to aldehydes including aqueous formaldehyde.
- Yamamoto, Tetsuya,Furusawa, Takuma,Zhumagazin, Azamat,Yamakawa, Tetsu,Oe, Yohei,Ohta, Tetsuo
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- Synthesis of cannabinol by a modified Ullmann-ziegler cross-coupling
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Cannabinol, a pharmaceutically interesting component of cannabis, was prepared by a modified Ullmann-Ziegler cross-coupling. Using easily obtainable starting materials, this convergent approach allows facile access to a variety of cannabinol derivatives. Georg Thieme Verlag Stuttgart New York.
- Nüllen, Max P.,G?ttlich, Richard
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p. 1109 - 1112
(2013/06/27)
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- A scalable process for the synthesis of (E)-pterostilbene involving aqueous Wittig olefination chemistry
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A synthetic approach toward the pharmacologically active (E)-stilbene pterostilbene is described using a Wittig reaction conducted under mildly basic, aqueous conditions. A surprising, non-intuitive difference in (E)/(Z) stereoselectivity was observed comparing the two possible isomeric Wittig routes, allowing for the development of a highly efficient process to access the title stilbene derivative through a one-pot olefination deprotection sequence.
- McNulty, James,McLeod, David
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p. 6303 - 6306
(2013/11/06)
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- Scope and limitations of the Heck-Matsuda-coupling of phenol diazonium salts and styrenes: A protecting-group economic synthesis of phenolic stilbenes
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4-Phenol diazonium salts undergo Pd-catalyzed Heck reactions with various styrenes to 4′-hydroxy stilbenes. In almost all cases higher yields and fewer side products were observed, compared to the analogous 4-methoxy benzene diazonium salts. In contrast, the reaction fails completely with 2- and 3-phenol diazonium salts. For these substitution patterns the methoxy-substituted derivatives are superior. The Royal Society of Chemistry 2013.
- Schmidt, Bernd,Elizarov, Nelli,Berger, René,H?lter, Frank
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supporting information
p. 3674 - 3691
(2013/06/27)
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- Facile and efficient KOH-catalysed reduction of esters and tertiary amides
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Esters and tertiary amides were efficiently reduced to their corresponding alcohols and amines in high yields under mild and environmentally friendly conditions. The presented KOH-catalysed system involves a simple hydrosilylation procedure that is carried out under solvent-free conditions and does not require the use of inert conditions.
- Fernandez-Salas, Jose A.,Manzini, Simone,Nolan, Steven P.
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supporting information
p. 9758 - 9760
(2013/10/21)
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- Ultrasound promoted Barbier reactions and Csp3-Csp2 Stille coupling for the synthesis of diarylmethanes and substituted benzophenones
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Here we present the preparation of a variety of diarylmethanes obtained via ultrasound Stille coupling under palladium catalysis between some substituted aryl compounds and benzyltributyltin compounds generated through sonicated Barbier reaction in a very short time reaction and excellent yield. The study reported below compares different methods to optimize the synthesis of usually unstable benzyltin derivatives and is another contribution to the investigation of Csp3-Csp2 coupling process involving benzyl-aryl reagents. Substituted carboxylated benzophenones were easily prepared in a very good yield by oxidation of some diarylmethanes.
- Ocampo, Romina A.,Koll, Liliana C.,Mandolesi, Sandra D.
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- Pd-catalyzed direct arylation approach to the 6H-dibenzo[c,h]chromenes: Total synthesis of arnottin I
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An efficient synthesis of 6H-dibenzo[c,h]chromenes has been achieved from 2-bromobenzyl-α-naphthyl ethers via a Pd-catalyzed Intramolecular direct-arylation using easily available Pd(PPh3)4 or Pd(OAc)2/PPh3 at elevated temperature. The reaction affords biaryl-coupling products in good to excellent yields in 6-9 h (up to 94% yields). A tentative mechanism has been proposed to understand the reaction pathway. Applying the methodology, a straightforward and concise total synthesis of arnottin I has been demonstrated by converting the biaryl-coupling products to the 6H-benzo[d]naphtho[1,2-b]pyran-6-one using pyridinium chlorochromate (PCC) mediated oxidation.
- De, Subhadip,Chaudhuri, Saikat,Mishra, Sourabh,Mamtani, Himanshu,Bisai, Alakesh
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p. 1871 - 1884
(2014/01/17)
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- Synthesis of combretastatin A4 analogues on steroidal framework and their anti-breast cancer activity
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Combretastatin A4 analogues were synthesized on steroidal framework from gallic acid with a possibility of anti-breast cancer agents. Twenty two analogues were synthesized and evaluated for cytotoxicity against human breast cancer cell lines (MCF-7 & MDA-MB 231). The best analogue 22 showed potent antitubulin effect. Docking experiments also supported strong binding affinity of 22 to microtubule polymerase. In cell cycle analysis, 22 induced apoptosis in MCF-7 cells significantly. It was found to be non-toxic up to 300 mg/kg dose in Swiss albino mice in acute oral toxicity. This article is part of a Special Issue entitled "Synthesis and biological testing of steroid derivatives as inhibitors".
- Parihar, Swati,Kumar, Amit,Chaturvedi, Amit K.,Sachan, Naresh Kumar,Luqman, Suaib,Changkija, Bendangla,Manohar, Murli,Prakash, Om,Chanda,Khan, Feroz,Chanotiya,Shanker, Karuna,Dwivedi, Anila,Konwar, Rituraj,Negi, Arvind S.
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p. 332 - 344
(2013/11/19)
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- Cobalt-catalyzed transfer hydrogenation of C=O and C=N bonds
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An earth-abundant metal cobalt catalyst has been developed for the transfer hydrogenation of ketones, aldehydes, and imines under mild conditions. Experiments are described which provide insights into the mechanism of the transfer hydrogenation reaction. The Royal Society of Chemistry 2013.
- Zhang, Guoqi,Hanson, Susan K.
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supporting information
p. 10151 - 10153
(2013/10/22)
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- Synthesis, in vitro antimycobacterial and antibacterial evaluation of IMB-070593 derivatives containing a substituted benzyloxime moiety
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A series of novel IMB-070593 derivatives containing a substituted benzyloxime moiety and displaying a remarkable improvement in lipophilicity were synthesized and evaluated for their in vitro antimycobacterial and antibacterial activity. Our results reveal that the target compounds 19a-m have considerable Gram-positive activity (MIC: 0.008-32 μg/mL), although they are generally less active than the reference drugs against the Gram-negative strains. In particular, compounds 19h, 19j, 19k and 19m show good activity (MICs: 0.008-4 μg/mL) against all of the tested Gram-positive strains, including ciprofloxacin (CPFX)- and/or levofloxacin (LVFX)-resistant MSSA, MRSA and MSSE. Moreover, compound 19l (MIC: 0.125 μg/mL) is found to be 2-4 fold more active than the parent IMB070593, CPFX and LVFX against M. tuberculosis H37Rv ATCC 27294.
- Wei, Zengquan,Wang, Jian,Liu, Mingliang,Li, Sujie,Sun, Lanying,Guo, Huiyuan,Wang, Bin,Lu, Yu
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p. 3872 - 3893
(2013/06/05)
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- Asymmetric total syntheses of cochliomycin A and zeaenol
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The first asymmetric total syntheses of two resorcylic acid lactones (RALs) - cochliomycin A and zeaenol - have been achieved in a divergent way. The main highlight of our strategy involves successful application of stereoselecive Keck allylation and Julia-Kocienski olefination to access an advanced intermediate, by starting from L-tartaric acid as a chiral pool compound. This intermediate is coupled with a trisubstituted benzoic acid to afford a common RCM precursor for both target molecules. Ring-closing metathesis at a late stage, followed by functional group manipulation, yielded the target molecules in an efficient way. Two resorcylic acid lactones (RALs) - cochliomycin A and zeaenol - have been synthesized for the first time by an enantiodivergent route from the common chiral pool compound L-tartaric acid. Copyright
- Jana, Nandan,Nanda, Samik
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p. 4313 - 4320
(2012/09/22)
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- Dimerization of resveratrol trimethyl ether by phosphotungstic acid, structure confirmation of resformicol A and B
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Dimerization of the trimethyl ether of resveratrol catalyzed by phosphotungstic acid gave two tetralins and a naphthalene derivative. The structure of the tetralins was obtained by X-ray crystallography and confirms the reported stereochemical configuration of resformicol A and B.
- Davis, Matthew C.,Groshens, Thomas J.
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supporting information; experimental part
p. 3521 - 3523
(2012/08/29)
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- Practical preparation of resveratrol 3-O-β-D-glucuronide
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A practical synthesis of resveratrol 3-Oβl-D-glucuronide, suitable for preparation of large quantities, was developed using selective deacetylation of resveratrol triacetate with ammonium acetate. A simplified procedure for large-scale preparation of resveratrol is also reported.
- Jungong, Christian S.,Novikov, Alexei V.
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p. 3589 - 3597,9
(2020/08/31)
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- Geographic variability and anti-staphylococcal activity of the chrysophaentins and their synthetic fragments
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Drug-resistant Staphylococcus aureus is a continuing public health concern, both in the hospital and community settings. Antibacterial compounds that possess novel structural scaffolds and are effective against multiple S. aureus strains, including current drug-resistant ones, are needed. Previously, we have described the chrysophaentins, a family of bisdiarylbutene macrocycles from the chrysophyte alga Chrysophaeum taylori that inhibit the growth of S. aureus and methicillin-resistant S. aureus (MRSA). In this study we have analyzed the geographic variability of chrysophaentin production in C. taylori located at different sites on the island of St. John, U.S. Virgin Islands, and identified two new linear chrysophaentin analogs, E2 and E3. In addition, we have expanded the structure activity relationship through synthesis of fragments comprising conserved portions of the chrysophaentins, and determined the antimicrobial activity of natural chrysophaentins and their synthetic analogs against five diverse S. aureus strains. We find that the chrysophaentins show similar activity against all S. aureus strains, regardless of their drug sensitivity profiles. The synthetic chrysophaentin fragments indeed mimic the natural compounds in their spectrum of antibacterial activity, and therefore represent logical starting points for future medicinal chemistry studies of the natural products and their analogs.
- Keffer, Jessica L.,Hammill, Jared T.,Lloyd, John R.,Plaza, Alberto,Wipf, Peter,Bewley, Carole A.
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experimental part
p. 1103 - 1125
(2012/08/14)
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- Mild and homogeneous cobalt-catalyzed hydrogenation of C=C, C=O, and C=N bonds
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A cationic cobalt(II)-alkyl complex is an effective precatalyst for hydrogenation of alkenes, aldehydes, ketones, and imines under mild conditions (1-4 atm H2; see scheme). The catalyst shows a high functional-group tolerance across a broad range of substrates. Experiments suggest that the active catalytic species is a cobalt(II)-hydride complex. Copyright
- Zhang, Guoqi,Scott, Brian L.,Hanson, Susan K.
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supporting information
p. 12102 - 12106
(2013/01/16)
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- Indium tri(isopropoxide)-catalyzed selective Meerwein-Ponndorf-Verley reduction of aliphatic and aromatic aldehydes
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Indium tri(isopropoxide)-catalyzed Meerwein-Ponndorf-Verley reduction of aliphatic and aromatic aldehydes in 2-propanol gave selectively the corresponding primary alcohols in good to excellent yields at room temperature. A wide range of functional groups including alkene, ether, ketone, ester, nitrile, and nitro were tolerated under the optimum reaction conditions. Chemoselective reductions were also achieved not only between aromatic aldehyde, aromatic ketone, and epoxide but also between aliphatic aldehyde and alkene.
- Lee, Jaeyoung,Ryu, Taekyu,Park, Sangjune,Lee, Phil Ho
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supporting information; experimental part
p. 4821 - 4825
(2012/07/03)
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- Design, synthesis, and evaluation of resveratrol derivatives as Ass1-42 aggregation inhibitors, antioxidants, and neuroprotective agents
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A series of novel resveratrol derivatives were designed, synthesised and evaluated as potential therapeutic agents for the treatment of Alzheimer's disease. Among these compounds, compound 7l, (E)-5-(4-(isopropylamino)styryl) benzene-1,3-diol, exhibited potent ss-amyloid aggregation inhibition activity, which was confirmed by a ThT fluorescence assay (71.65% at 20 μM) and transmission electron microscopy (TEM). Compound 7l also exhibited good antioxidant activity (4.12 Trolox equivalents in an oxygen radical absorbance capacity assay and a 37% reduction in reactive oxygen species in cells at 10 μM). The cytotoxicity analysis of compounds 7f, 7i, 7j and 7l indicated that these compounds have lower toxicities than resveratrol at 60 μM.
- Lu, Chuanjun,Guo, Yueyan,Li, Jianheng,Yao, Meicun,Liao, Qiongfeng,Xie, Zhiyong,Li, Xingshu
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supporting information
p. 7683 - 7687
(2013/02/21)
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- Alkene hydrogenation catalyzed by nickel hydride complexes of an aliphatic PNP pincer ligand
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To investigate metal-ligand cooperativity as a strategy for promoting nickel-catalyzed alkene hydrogenation, cationic and neutral nickel(II) hydride complexes of the aliphatic pincer ligand PNHPCy {PNHPCy = HN[CH2CH2P(Cy)2]2} have been synthesized and characterized. Cationic hydride complex [(PNHP Cy)Ni(H)]BPh4 (2) catalyzed the hydrogenation of styrene and 1-octene under mild conditions. Only low conversion was observed in the hydrogenation of 3,5-dimethoxybenzaldehyde using 2. The neutral hydride complex (PNPCy)Ni(H) (3) was also found to be an alkene hydrogenation catalyst. Mechanistic experiments suggest that for catalyst 2, the hydrogenation reaction proceeds through a pathway involving initial insertion of the alkene into the Ni-H bond. Contrary to the initial hypothesis, reactivity comparisons with the methyl-substituted hydride complex [(PNMePCy)Ni(H)]BPh 4 {PNMePCy = (CH3)N[CH2CH 2P(Cy)2]2} suggest that metal-ligand cooperativity is not involved in these rare examples of mild and homogeneous nickel hydrogenation catalysis. Copyright
- Vasudevan, Kalyan V.,Scott, Brian L.,Hanson, Susan K.
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p. 4898 - 4906
(2013/01/15)
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