- Antibody-catalyzed enantioselective Norrish type II cyclization
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Excellent enantioselectivity (up to 96% ee) was attained in an antibodycatalyzed photochemical Norrish type II reaction, which proceeded via the intermediate diradical 1 to produce the cyclobutanols 4 (absolute stereochemistry unknown). Use of the antibod
- Saphier, Sigal,Sinha, Subhash C.,Keinan, Ehud
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Read Online
- Highly selective flurogenic chemosensor for cyanide ion in aqueous medium and its applications of logic gate and Hela cells
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We have successfully synthesized triphenylamine-based fluorophores (MK and HK) with cyanoacrylic acid as a receptor for CN– ion sensing in a 99% aqueous medium. From the emission titration spectra, the detection limit of cyanide ion calculated towards MK and HK, respectively, are 234 nM and 11 nM. The observed binding constants for MK and HK, respectively, are 27 × 10-3 M and 10 X 10-2 M. The plausible sensing mechanism is confirmed by various methods such as Job's plot experiment, proton NMR titration, and density functional theory. Furthermore, the prominent application is the naked-eye detection of cyanide from non-fluorescent to greenish-yellow fluorescent under 365 nm UV light. Based on the observed data from fluorescence spectroscopic studies, a new logic circuit is designed. Moreover, the potential application of HK and MK in the Hela cell line exhibited turn on fluorescence image for cyanide ion through the inhibition of the ICT process. In addition to that, the probe MK and HK is successfully applied in the analysis of the real sample for the rapid detection of cyanide ions.
- Muniyasamy, Harikrishnan,Chinnadurai, Chithiraikumar,Nelson, Malini,Kubendran, Aravind Manikka,Sukumaran, Karthika,Balasubramaniem, Ashokkumar,Sepperumal, Murugesan,Ayyanar, Siva,Govindasamy, Mani,Ghfar, Ayman,Alsubaied, Fehaid Mohammed
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Read Online
- Functionalized styrene synthesis via palladium-catalyzed C[sbnd]C cleavage of aryl ketones
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We report herein the synthesis of functionalized styrenes via palladium-catalyzed Suzuki–Miyaura cross-coupling reaction between aryl ketone derivatives and potassium vinyltrifluoroborate. The employment of pyridine-oxazoline ligand was the key to the cleavage of unstrained C[sbnd]C bond. A variety of functional groups and biologically important moleculars were well tolerated. The orthogonal Suzuki–Miyaura coupling demonstrated the synthetic practicability.
- Zhang, Xu,Wang, Zhen-Yu,Wang, Xing,Xu, Hui,Dai, Hui-Xiong
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- Nickel-Catalyzed Reductive Cross-Coupling of Aryl Bromides with Vinyl Acetate in Dimethyl Isosorbide as a Sustainable Solvent
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A nickel-catalyzed reductive cross-coupling has been achieved using (hetero)aryl bromides and vinyl acetate as the coupling partners. This mild, applicable method provides a reliable access to a variety of vinyl arenes, heteroarenes, and benzoheterocycles, which should expand the chemical space of precursors to fine chemicals and polymers. Importantly, a sustainable solvent, dimethyl isosorbide, is used, making this protocol more attractive from the point of view of green chemistry.
- Su, Mincong,Huang, Xia,Lei, Chuanhu,Jin, Jian
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supporting information
p. 354 - 358
(2022/01/15)
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- Design of Negative and Positive Allosteric Modulators of the Cannabinoid CB2Receptor Derived from the Natural Product Cannabidiol
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Cannabidiol (CBD), the second most abundant of the active compounds found in the Cannabis sativa plant, is of increasing interest because it is approved for human use and is neither euphorizing nor addictive. Here, we design and synthesize novel compounds taking into account that CBD is both a partial agonist, when it binds to the orthosteric site, and a negative allosteric modulator, when it binds to the allosteric site of the cannabinoid CB2 receptor. Molecular dynamic simulations and site-directed mutagenesis studies have identified the allosteric site near the receptor entrance. This knowledge has permitted to perform structure-guided design of negative and positive allosteric modulators of the CB2 receptor with potential therapeutic utility.
- Navarro, Gemma,Gonzalez, Angel,Sánchez-Morales, Adrià,Casajuana-Martin, Nil,Gómez-Ventura, Marc,Cordomí, Arnau,Busqué, Félix,Alibés, Ramon,Pardo, Leonardo,Franco, Rafael
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p. 9354 - 9364
(2021/07/19)
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- Synthesis, Biological Evaluation of ortho-Carboxamidostilbenes as Potential Inhibitors of Hyperglycemic Enzymes, and Molecular Docking Study
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A new series of ortho-carboxamidostilbenes derivatives were synthesized via Heck Coupling and screened for their α-amylase and α-glucosidase inhibitory potential. The results indicated that all the synthesized compounds showed a substantial α-glucosidase
- Abu Bakar, Mohamad Hafizi,Awang, Khalijah,Azmi, Mohamad Nurul,Che Omar, Mohammad Tasyriq,Mohamad, Norhadi,Phua, Yoong Hui,Supratman, Unang,Wahab, Habibah A.
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- Hydrazide-Catalyzed Polyene Cyclization: Asymmetric Organocatalytic Synthesis of cis-Decalins
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Polyene cyclizations offer rapid entry into terpenoid ring systems. Although enantioselective cyclizations of (E)-polyenes to form trans-decalin ring systems are well precedented, highly enantioselective cyclizations of (Z)-polyenes to form the correspond
- Plamondon, Samuel J.,Warnica, Josephine M.,Kaldre, Dainis,Gleason, James L.
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supporting information
p. 253 - 258
(2019/11/28)
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- Preparation method of alkyl nitrile compound
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The invention discloses a preparation method of an alkyl nitrile compound. Specifically, the preparation method comprises the following step: in an organic solvent, in the presence of a protective gasand under the action of a catalyst, carrying out a reduction reaction as shown in the specification on olefin as shown in a formula I, a cyanation reagent and water, wherein the alkyl nitrile compound 1 is a compound II and/or a compound III. The preparation method provided by the invention is mild in condition, can realize hydrocyanation of olefin more safely and efficiently, and has good substrate universality and functional group compatibility.
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Paragraph 0110-0112
(2020/08/18)
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- cis-Selective Transfer Semihydrogenation of Alkynes by Merging Visible-Light Catalysis with Cobalt Catalysis
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Herein, the first example of visible-light-driven, cobalt-catalyzed transfer semihydrogenation of alkynes to alkenes is reported. It is carried out by using Ir[dF(CF3)ppy]2(dtbbpy)]PF6 as photosensitizer, CoBr2/n-Bu3P as proton-reducing catalyst, and i-Pr2NEt/AcOH as the hydrogen source. Under the established catalytic system, the semihydrogenation proceeds with Z as the major selectivity and with inhibition of over-reduction. Under mild reaction conditions, both internal and terminal alkynes, as well as reducible functional groups such as halogen, cyano, and ester, are tolerated. Preliminary mechanistic studies revealed the dual role of the photosensitizer in initiating the reaction via a single-electron transfer process and controlling the stereoselectivity via an energy transfer process. (Figure presented.).
- Ding, Hai-Xin,Guo, Wen-Jie,He, Yong-Qin,Song, Xian-Rong,Tian, Wan-Fa,Xiao, Qiang,Ye, Jing
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supporting information
(2020/02/05)
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- Selective Transfer Semihydrogenation of Alkynes with H2O (D2O) as the H (D) Source over a Pd-P Cathode
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We reported a selective semihydrogenation (deuteration) of numerous terminal and internal alkynes using H2O (D2O) as the H (D) source over a Pd-P alloy cathode at a lower potential. P-doping caused the enhanced specific adsorption of alkynes and the promoted intrinsic activity for producing adsorbed atomic hydrogen (H*ads) from water electrolysis. The semihydrogenation of alkynes could be accomplished at a lower potential with up to 99 % selectivity and 78 % Faraday efficiency of alkene products, outperforming pure Pd and commercial Pd/C. This electrochemical semihydrogenation of alkynes might proceed via a H*ads addition pathway rather than a proton-coupled electron transfer process. The decreased amount of H*ads at a lower potential and the more preferential adsorption of the Pd-P to C≡C π bond than C=C moiety resulted in the excellent alkene selectivity. This method was capable of producing mono-, di-, and tri-deuterated alkenes with up to 99 % deuterium incorporation.
- Liu, Cuibo,Lu, Siyu,Wang, Changhong,Wu, Yongmeng,Zhang, Bin
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supporting information
p. 21170 - 21175
(2020/09/11)
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- Design and Synthesis of Metabolically Stable tRNA Synthetase Inhibitors Derived from Cladosporin
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Selective and specific inhibitors of Plasmodium falciparum lysyl-tRNA synthetase represent promising therapeutic antimalarial avenues. Cladosporin was identified as a potent P. falciparum lysyl-tRNA synthetase inhibitor, with an activity against parasite
- Rusch, Marion,Thevenon, Arnaud,Hoepfner, Dominic,Aust, Thomas,Studer, Christian,Patoor, Maude,Rollin, Patrick,Livendahl, Madeleine,Ranieri, Beatrice,Schmitt, Esther,Spanka, Carsten,Gademann, Karl,Bouchez, Laure C.
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p. 644 - 649
(2019/02/13)
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- Method for synthesizing olefin compound by photo-induced one-pot process
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The invention discloses a method for synthesizing an olefin compound by a photo-induced one-pot process. The method comprises the following step of subjecting a halohydrocarbon and an aldehyde compound to a reaction under the condition of irradiation in an inert atmosphere by taking alkali metal carbonate as a base, taking an organic phosphine compound as an adjuvant and taking a photosensitizer as a catalyst, thereby obtaining the olefin compound. According to the method disclosed by the invention, the olefin compound is produced from the halohydrocarbon and the aldehyde compound in a high-yield manner under the condition of irradiation in the inert atmosphere under normal-temperature reaction conditions by taking acetonitrile, DMF (N,N-dimethylformamide) or DMA (N,N-dimethylacetamide) asa solvent, taking an organic phosphine reagent as a reaction adjuvant, taking the alkali metal carbonate as the base and taking the photosensitizer as the catalyst. Compared with the conventional olefin synthesis methods, the method disclosed by the invention has the obvious advantages that the reaction raw materials are readily available, the tolerance to a variety of functional groups on halohydrocarbons and aldehydes is high, the yield is high, the separation and purification of a product are simple and convenient, and the like.
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Paragraph 0081-0083
(2018/11/03)
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- Novel Hybrid Conjugates with Dual Suppression of Estrogenic and Inflammatory Activities Display Significantly Improved Potency against Breast Cancer
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In this work, we developed a small library of novel OBHS-RES hybrid compounds with dual inhibition activities targeting both the estrogen receptor α (ERα) and NF-?B by incorporating resveratrol (RES), a known inhibitor of NF-?B, into a privileged indirect antagonism structural motif (OBHS, oxabicycloheptene sulfonate) of estrogen receptor (ER). The OBHS-RES conjugates could bind well to ER and showed remarkable ERα antagonistic activity, and they also exhibited excellent NO inhibition in macrophage RAW 264.7 cells. Compared with 4-hydroxytamoxifen, some of them showed better antiproliferative efficacy in MCF-7 cell lines with IC50 up to 3.7 μM. In vivo experiments in a MCF-7 breast cancer model in Balb/c nude mice indicated that compound 26a was more potent than tamoxifen. Exploration of the compliancy of the structure against ER specificity utilizing these types of isomeric three-dimensional ligands indicated that one enantiomer had much better biological activity than the other.
- Ning, Wentao,Hu, Zhiye,Tang, Chu,Yang, Lu,Zhang, Silong,Dong, Chune,Huang, Jian,Zhou, Hai-Bing
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supporting information
p. 8155 - 8173
(2018/08/09)
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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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- Model Guided Development of a Simple Catalytic Method for the Synthesis of Unsymmetrical Stilbenes by Sequential Heck Reactions of Aryl Bromides with Ethylene
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Stilbenes are important and useful structural moieties, but methods for their preparation typically possess numerous inefficiencies. Presented here is a methodology for the two-step, one pot preparation of unsymmetrical stilbenes via sequential Heck reactions. The first Heck reaction with ethylene gas was analysed as a function of temperature and pressure for electronically differentiated naphthyl bromides and model-aided reaction optimization was utilized to define the system. In addition, reactNMR was utilized to determine ethylene solubility in common organic solvents useful for Heck reactions. Finally, an optimized sequential Heck reaction process was developed and applied to a range of substrates allowing for efficient preparation of unsymmetrical stilbenes, including the natural antioxidant, pterostilbene. (Figure presented.).
- Barlow, Helen,Buser, Jonas Y.,Glauninger, Hendrik,Luciani, Carla V.,Martinelli, Joseph R.,Oram, Niall,Thompson-Van Hook, Nichole,Richardson, Jeffery
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p. 2678 - 2690
(2018/06/04)
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- Total Synthesis and Cytotoxic Activity of 5′-Hydroxyzearalenone and 5′β-Hydroxyzearalenone
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An efficient and convergent synthesis of 5′-hydroxyzearalenone and 5′β-hydroxyzearalenone, 14-membered β-resorcylic acid lactone (RAL) natural products, has been achieved in a longest linear sequence of 19 steps, and a total of 29 steps, starting from commercially available 5-hexen-1-ol and methyl 2-(3,5-dimethoxyphenyl)acetate. The key features of our synthesis include a Jacobsen hydrolytic kinetic resolution, a Mitsunobu esterification and (an E)-selective ring-closing metathesis (RCM). Our synthesis also highlights the utility of the acetal protecting group for the resorcylate moiety, and its compatibility with RCM reactions for the synthesis of 14-membered RALs. The cytotoxic activity of both synthetic compounds was evaluated against seven human cancer cell lines. 5′-Hydroxyzearalenone shows more potent cytotoxic activity against most of the cancer cell lines tested than its epimer, 5′β-hydroxyzearalenone. Both compounds show significant cytotoxic activity against the C33A cervical cancer cell line, with IC50 values of 21.33 ± 6.43 μm and 16.00 ± 12.17 μm, respectively.
- Thiraporn, Aticha,Rukachaisirikul, Vatcharin,Iawsipo, Panata,Somwang, Tatiyar,Tadpetch, Kwanruthai
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supporting information
p. 7133 - 7147
(2017/12/28)
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- Oxygen bridge dicycloheptene compound containing resveratrol group and its preparation method and use method
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The invention belongs to the technical field of medicine and discloses a preparation method of an oxygen bridge dicycloheptene compound containing a resveratrol group. One of a 3-(4-hydroxyphenyl)-4-(((E)-3, 5-dihydroxystyryl)phenyl)furan compound and a 3
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Paragraph 0046; 0058; 0059
(2017/10/10)
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- Discovery of efficient stimulators for adult hippocampal neurogenesis based on scaffolds in dragon's blood
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Reduction of hippocampal neurogenesis caused by aging and neurological disorders would impair neural circuits and result in memory loss. A new lead compound (N-trans-3′,4'-methylenedioxystilben-4-yl acetamide 27) has been discovered to efficiently stimulate adult rats' neurogenesis. In-depth structure-activity relationship studies proved the necessity of a stilbene scaffold that is absent in highly cytotoxic analogs such as chalcones and heteroaryl rings and inactive analogs such as diphenyl acetylene and diphenyl ethane, and validated the importance of an NH in the carboxamide and a methylenedioxy substituent on the benzene ring. Immunohistochemical staining and biochemical analysis indicate, in contrast to previously reported neuroprotective chemicals, N-stilbenyl carboxamides have extra capacity for neuroproliferation-type neurogenesis, thereby providing a foundation for improving the plasticity of the adult mammalian brain.
- Liang, Jian-Hua,Yang, Liang,Wu, Si,Liu, Si-Si,Cushman, Mark,Tian, Jing,Li, Nuo-Min,Yang, Qing-Hu,Zhang, He-Ao,Qiu, Yun-Jie,Xiang, Lin,Ma, Cong-Xuan,Li, Xue-Meng,Qing, Hong
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supporting information
p. 382 - 392
(2017/05/19)
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- Anti-diabetic activity of fused PPARγ-SIRT1 ligands with limited body-weight gain by mimicking calorie restriction and decreasing SGK1 expression
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A series of benzothiazol-2-one containing α-ethoxyphenylpropionic acid derivatives incorporating resveratrol or butein scaffolds were designed as fused full PPARγ agonist ligands and SIRT1-activating compounds for the treatment of type 2 diabetes (T2D) an
- Pirat, Celine,Dacquet, Catherine,Leclerc, Veronique,Hennuyer, Nathalie,Beucher-Gaudin, Monique,Zanirato, Ghislaine,Géant, Anne,Staels, Bart,Ktorza, Alain,Farce, Amaury,Caignard, Daniel-Henri,Berthelot, Pascal,Lebegue, Nicolas
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p. 310 - 326
(2017/06/14)
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- Active Ruthenium (0) Nanoparticles Catalyzed Wittig-Type Olefination Reaction
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Abstract: Five different Ru metal precursors were reduced in imidazolium based ionic liquids under hydrogen atmosphere (4?bar) at 50 °C to obtain well-dispersed and stable Ru nanoparticles. Transmission electron microscopy (TEM) analysis confirmed size of well dispersed ionic liquid mediated Ru particles (Ru NPs) of 5?nm (±0.5) in diameter. These ruthenium nanoparticles (in ionic liquids) were used for Wittig type olefination reaction under mild reaction environment (70 °C and 1?h). The corresponding stilbenes were obtained in good yield with low-average selectivity. The proposed methodology is especially efficient for the synthesis of stilbenes as they were synthesized in the absence of any additive (as a hydrogen acceptor). The new catalytic system was also successfully applied for the synthesis of polymethoxylated and polyhydroxylated stilbenes, including resveratrol and DMU-212. Graphical Abstract: [Figure not available: see fulltext.]
- Srivastava, Vivek
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p. 693 - 703
(2017/03/08)
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- Novel stilbene derivative and preparation method thereof
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The invention provides a novel stilbene derivative. The novel stilbene derivative is a compound with a general formula I or II as described in the specification or a salt formed by the compound with the general formula I or II as described in the specification and inorganic acid or organic acid. In the general formula I or II, X represents a hydrogen atom or halogen atom; R represents a substituent selected from a group consisting of C1-5 alkyl groups, C2-4 alkenyl groups, C2-4 alkynyl groups, C3-6 cycloalkyl groups, five-to-twelve-component aryl groups, two-to-five-component heteralkyl groups, three-to-six-component hetercycloalkyl groups, five-to-twelve-component heteraryl groups, substituted three-to-six-component cycloalkanes, substituted five-to-twelve-component aryl groups and substituted five-to-twelve-component heteralkyl groups; or the substituent represented by R is a first substituent formed by a spacer group and any one selected from a group consisting of C3-6 cycloalkanes, three-to-six-component hetercycloalkanes, five-to-twelve-component aryl groups and five-to-twelve-component heteraryl groups, and the spacer group comprises -CH2-, -(CH2)2-, -CH=CH-, -CH2O-, -CH(OCH3)- and -CH2S-.
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Paragraph 0137; 0138; 0247; 0248
(2017/04/22)
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- Novel Resveratrol-Based Aspirin Prodrugs: Synthesis, Metabolism, and Anticancer Activity
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(Graph Presented). Regular aspirin use has been convincingly shown to reduce the risk of colorectal cancer. However, long-term use of aspirin leads to gastrotoxicity. Herein, we designed and synthesized a novel class of resveratrol-based aspirin prodrugs to simultaneously release aspirin and resveratrol to attenuate the side effects caused by aspirin. Prodrug RAH exerted enhanced anticancer activities which are better than a physical mixture of aspirin and resveratrol as well as each individually. Metabolism of RAH in mice showed that the majority of RAH is decomposed to release resveratrol and aspirin or salicylic acid either in the intestine or after absorption. Mechanistic studies demonstrate RAH inhibits cell cycle arrest through downregulation of cyclins and induces apoptosis by activation of caspase-3 in cancer cells. These findings highlighted the improved anticancer properties of resveratrol-based aspirin prodrugs. RAH may represent novel and safe alternatives of aspirin for the purpose of daily use in the future.
- Zhu, Yingdong,Fu, Junsheng,Shurlknight, Kelly L.,Soroka, Dominique N.,Hu, Yuhui,Chen, Xiaoxin,Sang, Shengmin
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p. 6494 - 6506
(2015/09/08)
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- Room temperature hydrophosphination using a simple iron salen pre-catalyst
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Phosphines are fundamentally important to the fine chemicals, pharmaceutical and agrochemical industries. Reported is the first example of alkene hydrophosphination using a designed iron pre-catalyst which yields the anti-Markovnikov products in high yield at room temperature. The phosphine products are excellent pro-ligands for Fe-catalyzed Negishi cross-coupling. This journal is
- Gallagher,Webster
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supporting information
p. 12109 - 12111
(2015/01/08)
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- Small-molecule inhibitors of 25-hydroxyvitamin D-24-hydroxylase (CYP24A1): Synthesis and biological evaluation
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The synthesis of imidazole styrylbenzamide, tert-butyl styrylimidazole, and tert-butyl styrylsulfonate derivatives is described. Evaluation of binding affinity and inhibitory activity against CYP24A1 identified the imidazole styrylbenzamides as potent inhibitors of CYP24A1, having selectivity with respect to CYP27B1 comparable with or greater than that of the standard ketoconazole. Further evaluation of the 3,5-dimethoxy and 3,4,5-trimethoxy derivatives in chronic lymphocytic leukemia cells revealed that co-treatment of 1α,25-dihydroxyvitamin D3plus inhibitor coordinately upregulated GADD45α and CDKN1A. Docking experiments on the inhibitors in the CYP24A1 enzyme active site suggest the compounds reach the active site through the vitamin D access tunnel and are exposed to multiple hydrophobic residues. The imidazole styrylbenzamides are optimally positioned to allow interaction of the imidazole with the heme, and, in the case of the methoxy derivatives, a hydrogen bond between the 3-methoxy group and Gln82 stabilizes the molecule in a favorable active conformation.
- Ferla, Salvatore,Aboraia, Ahmed S.,Brancale, Andrea,Pepper, Christopher J.,Zhu, Jinge,Ochalek, Justin T.,Deluca, Hector F.,Simons, Claire
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p. 7702 - 7715
(2015/01/08)
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- Copper-catalyzed selective semihydrogenation of terminal alkynes with hypophosphorous acid
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A novel copper-catalyzed selective semihydrogenation of terminal alkynes using hypophosphorous acid as hydrogen donor took place efficiently to afford the corresponding alkenes in high yields. A broad range of substituted terminal aromatic and aliphatic alkenes, including terminal dienes and enynes bearing internal triple bonds, can be efficiently synthesized by this reaction.
- Cao, Huanyang,Chen, Tieqiao,Zhou, Yongbo,Han, Daoqing,Yin, Shuang-Feng,Han, Li-Biao
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p. 765 - 769
(2014/04/03)
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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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- Aspirin Derivatives and Uses Thereof
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The present invention provides novel aspirin derivatives useful for preventing and/or treating cancer. The novel compounds of this invention may be particularly useful for the prevention and/or treatment of cancers affecting the gastrointestinal system, s
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Paragraph 0197
(2014/02/15)
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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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experimental part
p. 4313 - 4320
(2012/09/22)
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- Copper-catalyzed reductive coupling of tosylhydrazones with amines: A convenient route to α-branched amines
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A general procedure for the reductive coupling of N-tosylhydrazones with amines in the presence of Cu(acac)2 and Cs2CO3 has been developed. The protocol is very effective and chemoselective with various primary and secondary aliphatic amines, aminoalcohols as well as azole derivatives to give α-branched amines in good yields.
- Hamze, Abdallah,Treguier, Bret,Brion, Jean-Daniel,Alami, Mouad
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p. 6200 - 6204
(2011/10/08)
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- Synthesis of the ABH rings of ecteinascidin 597 using a connective Pummerer-type cyclisation
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A connective Pummerer-type cyclisation involving a cysteine derivative and an N-benzyl glyoxamide 3 has been applied in an asymmetric synthesis of the protected ABH rings 2 of the antitumour and antimicrobial natural product ecteinascidin 597.
- Smith, Laura H. S.,Nguyen, Trung Thanh,Sneddon, Helen F.,Procter, David J.
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supporting information; experimental part
p. 10821 - 10823
(2011/11/05)
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- The synthesis of non-symmetrical stilbene analogs of trans-resveratrol using the same Pd catalyst in a sequential double-Heck arylation of ethylene
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We have developed a sequential and selective Pd-catalyzed double-Heck arylation of ethylene that results in non-symmetrical nitro-stilbene analogs of trans-resveratrol at excellent yields. A catalytic system consisting of Pd(OAc)2 and P(o-tolyl)3 permitted us to carry out the two consecutive Heck arylations without losing activity from the first to the second Heck reaction. After the first Heck arylation of ethylene, no isolation or additional catalyst loading is required for the second Heck arylation reaction. This protocol was applied to the synthesis of methylated trans-resveratrol, which was obtained at a 65% overall yield.
- Nobre, Sabrina M.,Muniz, Mauro N.,Seferin, Marcus,Da Silva, Wagner M.,Monteiro, Adriano L.
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experimental part
p. 289 - 293
(2012/01/04)
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- Oxime palladacycle-catalyzed Suzuki-Miyaura alkenylation of aryl, heteroaryl, benzyl, and allyl chlorides under microwave irradiation conditions
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A simple new protocol for the palladium-catalyzed Suzuki-Miyaura cross-coupling of organic chlorides under microwave irradiation is presented. Deactivated aryl and heteroaryl chlorides are efficiently cross-coupled with alkenylboronic acids and potassium alkenyltrifluoroborates using the 4,4′-dichlorobenzophenone oxime-derived palladacycle 1b as precatalyst in 0.1 to 0.5 mol% palladium loading, tris(tert-butyl)phosphonium tetrafluoroborate {[HP(t-Bu)3]BF4} as ligand, tetra-n-butylammonium hydroxide as cocatalyst, and potassium carbonate as base in N,N- dimethylformamide at 130°C under microwave irradiation conditions. Under these conditions, styrenes, stilbenes, and alkenylarenes are obtained in good to high yields, and with high regio- and diastereoselectivities in only 20 min. The reported protocol is also very efficient for the regioselective alkenylation of benzyl and allyl chlorides to afford allylarenes and 1,4-dienes. Copyright
- Civicos, Jose F.,Alonso, Diego A.,Najera, Carmen
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supporting information; experimental part
p. 1683 - 1687
(2011/09/19)
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- Design, synthesis, and biological evaluation of resveratrol analogues as aromatase and quinone reductase 2 inhibitors for chemoprevention of cancer
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A series of new resveratrol analogues were designed and synthesized and their inhibitory activities against aromatase were evaluated. The crystal structure of human aromatase (PDB 3eqm) was used to rationalize the mechanism of action of the aromatase inhibitor 32 (IC50 0.59 μM) through docking, molecular mechanics energy minimization, and computer graphics molecular modeling, and the information was utilized to design several very potent inhibitors, including compounds 82 (IC50 70 nM) and 84 (IC50 36 nM). The aromatase inhibitory activities of these compounds are much more potent than that for the lead compound resveratrol, which has an IC50 of 80 μM. In addition to aromatase inhibitory activity, compounds 32 and 44 also displayed potent QR2 inhibitory activity (IC 50 1.7 μM and 0.27 μM, respectively) and the high-resolution X-ray structures of QR2 in complex with these two compounds provide insight into their mechanism of QR2 inhibition. The aromatase and quinone reductase inhibitors resulting from these studies have potential value in the treatment and prevention of cancer.
- Sun, Bin,Hoshino, Juma,Jermihov, Katie,Marler, Laura,Pezzuto, John M.,Mesecar, Andrew D.,Cushman, Mark
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experimental part
p. 5352 - 5366
(2010/09/05)
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- Challenges associated with the synthesis of unusual o-carboxamido stilbenes by the Heck protocol: Intriguing substituent effects, their toxicological and chemopreventive implications
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The syntheses of fourteen unusual o-carboxamido stilbenes by the Heck protocol revealed surprising complexity related to intriguing substituent effects with mechanistic implications. The unexpected cytotoxic and chemopreventive properties also seem to be substituent dependent. For example, although stilbene 15d (with a 4-methoxy substituent) showed cytotoxicity on HT29 colon cancer cells with an IC50 of 4.9 μM, the 3,4-dimethoxy derivative (15c) is inactive. It is interesting to observe that the 3,5-dimethoxy derivative (15e) showed remarkable chemopreventive activity in WRL-68 fetal hepatocytes, surpassing the gold standard, resveratrol. The resveratrol concentration needed to be 5 times higher than that of 15e to produce comparable elevation of NQO1.
- Kee, Chin Hui,Ariffin, Azhar,Awang, Khalijah,Takeya, Koichi,Morita, Hiroshi,Hussain, Salmaan Inayat,Chan, Kok Meng,Wood, Pauline J.,Threadgill, Michael D.,Lim, Chuan Gee,Ng, Seikweng,Weber, Jean Frederic F.,Thomas, Noel F.
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experimental part
p. 5646 - 5660
(2011/02/18)
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- Wittig-type olefination of alcohols promoted by nickel nanoparticles: Synthesis of polymethoxylated and polyhydroxylated stilbenes
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Nickel nanoparticles were found to promote the Wittig-type olefination of primary alcohols with phosphorus ylides. The latter can be prepared from the corresponding phosphonium salts with TiBuLi or in situ generated with lithium metal. The methodology is especially efficient for the synthesis of stilbenes and is applied in the absence of any additive as a hydrogen acceptor. A new approach, to the synthesis of polymethoxylated and polyhydroxylated stilbenes, including resveratrol, DMU-212 and analogues, is presented.
- Alonso, Francisco,Riente, Paola,Yus, Miguel
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supporting information; experimental part
p. 6034 - 6042
(2010/02/28)
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- A FeCl3-promoted highly atropodiastereoselective cascade reaction: synthetic utility of radical cations in indolostilbene construction
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The FeCl3-promoted oxidative cyclization/coupling of acetamidostilbenes possessing 3-methoxy, 4-methoxy and 3,5-methoxy substitutions (21), (22) and (23) is described. Only 3,5-substitution gave rise to novel indolostilbenes, each possessing two stereogenic axes (axially chiral but racemic dimers (39) and (40)). The 4-methoxy substituted acetamidostilbenes, by contrast, yielded the bisindoline dimer (36).
- Ahmad, Kartini,Thomas, Noel F.,Mukhtar, Mat Ropi,Noorbatcha, Ibrahim,Faizal Weber, Jean-Frederic,Nafiah, Mohd Azlan,Velu, Saraswati S.,Takeya, Koichi,Morita, Hiroshi,Lim, Chuan-Gee,Hadi, A. Hamid A.,Awang, Khalijah
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experimental part
p. 1504 - 1516
(2009/05/07)
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- General reaction conditions for the palladium-catalyzed vinylation of aryl chlorides with potassium alkenyltrifluoroborates
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(Chemical Equation Presented) Activated and deactivated aryl and heteroaryl chlorides are efficiently cross-coupled with potassium vinyl- and alkenyltrifluoroborates using 4-hydroxyacetophenone oxime derived palladacycle as precatalyst in 1 to 3 mol % Pd loading, Binap as ligand, and Cs 2CO3 as base in DMF at 120°C. The reactions can also be performed using Pd(OAc)2 as Pd(0) source, although with lower efficiency. Bidentate ligands such as Binap and dppp can be used, the former being the best choice. Only in the case of deactivated aryl chlorides should the reaction temperature be increased to 160°C to achieve good yields. The corresponding cross-coupled compounds, such as styrenes, stilbenes, and alkenylarenes, are obtained in good yields and with high regio- and diastereoselectivity. 2009 American Chemical Society.
- Alacid, Emilio,Najera, Carmen
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supporting information; experimental part
p. 8191 - 8195
(2010/03/04)
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- Synthesis of substituted styrenes and stilbenes mediated by palladium on zirconia
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Palladium on zirconia has been found to be an effective catalyst for the synthesis of various substituted styrenes and stilbenes, including biologically active natural products, by reaction of aryl halides with olefins.
- Borate, Hanumant B.,Dumbre, Deepa K.,Wakharkar, Radhika D.,Choudhary, Vasant R.
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experimental part
p. 495 - 499
(2009/04/06)
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- Aqueous sodium hydroxide promoted cross-coupling reactions of alkenyltrialkoxysilanes under ligand-free conditions
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(Chemical Equation Presented) Fluoride-free cross-coupling reactions of alkenyltrialkoxysilanes with aryl iodides, bromides, and chlorides are performed on water using sodium hydroxide as activator at 120 °C under normal or microwave heating. This process occurs in the presence of Pd(OAc)2 or 4-hydroxyacetophenone oxime-derived palladacycle 1 as precatalysts under ligand-free conditions with low Pd loadings (0.01-1 mol %) and using tetra-n-butylammonium bromide as additive. Different commercially available vinylalkoxylsilanes can be cross-coupled under these reaction conditions to the corresponding styrenes, the best substrates being vinyltrimethoxy- or vinyltriethoxysilane. Alkenyltriethoxysilanes, prepared by Wilkinson-catalyzed hydrosilylation of alkynes with triethoxysilane, are stereospecifically arylated with aryl and vinyl halides under microwave irradiation in moderate to high β/α regioselectivity affording unsymmetrical stilbenes, alkenylbenzenes, and conjugate dienes, respectively. This simple procedure allows the palladium recycling from the aqueous phase during three runs by extractive separation of the products, which contain very low levels of Pd (21-27.5 ppm for an aryl iodide and up to 76 ppm for a bromide).
- Alacid, Emilio,Najera, Carmen
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p. 2315 - 2322
(2008/09/19)
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- Methoxy-substituted stilbenes, styrenes, and 1-arylpropenes: Photophysical properties and photoadditions of alcohols
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The photochemistry of trans-stilbene and four methoxy-substituted stilbene derivatives has been investigated in a variety of solvents. The fluorescence of all five trans isomers was quenched by 2,2,2-trifluoroethanol (TFE). Upon irradiation of the five substrates in TFE, the products derived from photoaddition of the solvent were detected. Nuclear magnetic resonance spectroscopy of the products formed by irradiation in TFE-OD indicated that the proton and nucleophile are attached to two adjacent atoms of the original alkene double bond. Irradiation of the corresponding methoxy-substituted styrenes and trans-1-arylpropenes in TFE produced the analogous solvent adducts. The photoaddition of TFE proceeded with the general order of reactivity: styre > trans-1-arylpropenes > trans-stilbenes. Transient carbocation intermediates were observed following laser flash photolysis of the stilbenes in 1,1,1,3,3,3-hexafluoro-2-propanol (HFIP). The results are consistent with a mechanism that involves photoprotonation of the substrates by TFE or HFIP, followed by nucleophilic trapping of short-lived carbocation intermediates. Compared to the other stilbene derivatives, trans-3,5-dimethoxystilbene displayed a large quantum yield of fluorescence and a low quantum yield of trans-cis isomerization in polar organic solvents. The unique photophysical properties of trans-3,5-dimethoxystilbene are attributed to formation of a highly polarized charge-transfer excited state (μe = 13.2 D).
- Roberts, Jeffrey C.,Pincock, James A.
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p. 1480 - 1492
(2007/10/03)
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- A simple access to biologically important trans-stilbenes via Ru-catalyzed cross metathesis
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The cross metathesis of methoxy- or acetoxy-substituted styrenes using the Grubbs II catalyst affords unsymmetrical (mixed) E-stilbenes with astonishingly high selectivity (up to 79% yield). This approach offers a short and flexible synthesis of variously substituted stilbenes, which are derivatives or precursors of biologically important compounds such as resveratrol, piceatannol, and pinostilbene. Georg Thieme Verlag Stuttgart.
- Velder, Janna,Ritter, Stefanie,Lex, Johann,Schmalz, Hans-Guenther
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p. 273 - 278
(2007/10/03)
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- Total synthesis of (±)-symbioimine
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(Chemical Equation Presented) An inside job: A Lewis acid induced intramolecular Diels-Alder (IMDA) reaction is used as the key step in the formation of symbioimine, an iminium alkaloid. The intermediate octahydronaphthalene is obtained from the IMDA reaction, after which extension of the aldehyde to a nitrile, alkylation of the nitrile, and imine formation allows for an efficient route to the target compound (see scheme; TBS = tert-butyldimethylsilyl).
- Varseev, Georgy N.,Maier, Martin E.
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p. 4767 - 4771
(2007/10/03)
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- Origin of selectivity in the antibody 20F10-catalyzed Yang cyclization
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The first antibody-catalyzed Yang (Norrish type II) cyclization has been achieved with antibodies that were elicited against cis- and trans-2,3-diaryloxetanes. The photocyclization of 1,4-diarylbutan-1-one produced a single stereoisomer of cis-1,2-diarylc
- Saphier, Sigal,Hu, Yunfeng,Sinha, Subhash C.,Houk,Keinan, Ehud
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p. 132 - 145
(2007/10/03)
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- Liquid-Crystalline Octopus Dendrimers: Block Molecules with Unusual Mesophase Morphologies
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The synthesis and the mesomorphic properties of several new main-chain liquid-crystalline dendrimers, thereafter designated as octopus dendrimers in accordance with their eight sidearms, are reported. In these dendritic systems, the arborescence is ensured by anisotropic segments, acting as branching cells with a double multiplicity, which are incorporated at every node of the dendritic architecture. In such a way, these compounds radically differ from the classical end-functionalized liquid-crystalline dendrimers, the most commonly reported systems. Following our previous report on purely homolithic systems, that is, the building blocks constituting the dendritic matrix are all identical, several heterolithic systems made of different anisotropic blocks have been prepared. The dendritic branches and corresponding dendrimers were synthesized using a modular construction. Polarized optical microscopy and X-ray diffraction studies showed that all of these new octopus dendrimers exhibit either smectic-like or columnar phases with novel morphologies, the nature of the mesophases depending on the number of terminal chains attached to the peripheral groups. The mesomorphism of these heterolithic dendrimers is discussed in terms of their intrinsic architecture and compared to the analogous homolithic octopus systems. Models for the molecular organizations within both the smectic and the columnar phases are proposed on the basis of small Bragg angle X-ray diffraction studies and are supported by molecular modelizations. Moreover, this study showed that the mesophase stability is very sensitive to the nature and to the mutual arrangement (the spatial location) of the mesogenic segments within the dendritic matrix, illustrating the intimate relationships existing between the mesomorphic properties and the molecular architecture of these dendrimers.
- Gehringer, Lionel,Bourgogne, Cyril,Guillon, Daniel,Donnio, Bertrand
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p. 3856 - 3867
(2007/10/03)
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- Liquid crystalline octopus: An alternative class of mesomorphic dendrimers
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The synthesis and the mesomorphic properties of a new series of liquid crystalline dendrimers, referred thereafter as to octopus dendrimers owing to their eight sidearms, are reported. In these dendritic systems, the arborescence is constituted of mesogen
- Gehringer, Lionel,Guillon, Daniel,Donnio, Bertrand
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p. 5593 - 5601
(2007/10/03)
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- Propiophenone derivatives and process for preparing the same
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A propiophenone derivative of the formula (I): wherein OX is a hydroxy group which may optionally be protected, Y is a lower alkyl group, and Z is a beta -D-glucopyranosyl group wherein one or more hydroxy groups may optionally be protected, or a pharmace
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- Total synthesis of vancomycin - Part 2: Retrosynthetic analysis, synthesis of amino acid building blocks and strategy evaluations
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Retrosynthetic analysis of vancomycin (1) defined vancomycin's aglycon (2) and protected triazene 3 (Figure 1) as advanced intermediates for an eventual total synthesis. Sequential assembly of 3 as shown in Figure 2 (strategy I) and Figure 3 (strategy II) led to amino acid building blocks 8-10 and 12-15, respectively, representing vancomycin's amino acids AA-1 to AA-7. These amino acid fragments were constructed by stereoselective routes and the two synthetic strategies were tested for feasibility. Strategy I, postulating construction of the vancomycin main framework in the order of D-O-E→D-O-E/C-O-D→D-O-E/C-O-D/A-B, suffered from serious epimerization problems at the AA-4 stereocenter; while strategy II, involving the sequence C-O-D→C-O-D/AB→C-O-D/AB/D-O-E proved viable. These findings set the stage for the final drive towards vancomycin's aglycon (2) and vancomycin (1).
- Nicolaou,Boddy, Christopher N. C.,Li, Hui,Koumbis, Alexandros E.,Hughes, Robert,Natarajan, Swaminathan,Jain, Nareshkumar F.,Ramanjulu, Joshi M.,Braese, Stefan,Solomon, Michael E.
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p. 2602 - 2621
(2007/10/03)
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- Oxocarbons and related compounds. 27. Synthesis of dihydrocyclobuta[a]naphthalene-1,2-diones and cyclobuta[a]naphthalene-1,2-diones via annulation of alkoxy-(1-alkenyl)benzenes with 3-chloro-3-cyclobutene-1,2-dione. Scope and limitations
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The reaction of alkoxy-(1-alkenyl)benzenes with semisquaric chloride (3) has been investigated systematically. 1,2-Dialkoxy- and 1-alkoxy′-2-alkoxy″-4-(1-alkenyl)benzenes (6a-j) and (11a-i) react with 3 to give the 3,4-dihydrocyclobuta[a]naphthalene-1,2-diones(8a-j) and (12a-i). Treatment of the dihydrocyclobuta[a]naphthalene-1,2-diones with 1.2 equiv. bromine effects dehydrogenation and affords cyclobuta[a]naphthalene-1,2-diones(9a-e) and (13b-f). Any efforts to extend this annulation reaction to dimethoxy-(1-alkenyl)benzenes with the methoxy groups in other than the 1,2-positions, e. g. 14a, b, 16a, b have been unsuccessful. The reaction of 1,2,3-trimethoxy-4-(1-propenyl) [and 4-(1-butenyl)]-benzenes (18a) and (18b) with semisquaric chloride (3) leads to the elimination of HCl and CH3OH and gives 5,6-dimethoxy-3-methyl [and 3-ethyl]-cyclobuta[a]naphthalene-1,2-diones (20a) and (20b). The reaction pathway of this novel annulation reaction is discussed.
- Schmidt, Arthur H.,Kircher, Gunnar,Spring, Mathias,Hendriok, Markus W.,Kuenz, Christian
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p. 564 - 574
(2007/10/03)
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- Synthetic studies towards glycopeptide antibiotics: Synthesis of the 16-membered cyclic tripeptide (DOEG ring) system of teicoplanin
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The synthesis of the 16-membered cyclic DOEG ring system of teicoplanin, which forms the binding pocked for the carboxylate region of terminal D-Ala-D-Ala of the bacterial cell wall via macroetherification of linear tripeptide 20 is described.
- Rama Rao,Laxma Reddy,Srinivasa Rao,Vittal,Reddy,Pathi
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p. 3023 - 3026
(2007/10/03)
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