- Polydiacetylene stabilized gold nanoparticles - extraordinary high stability and integration into a nanoelectrode device
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A new diacetylene containing photopolymerizable ligand molecule was developed, and tailored for applications in nanoelectronic devices based on gold nanoparticles. This ligand molecule consists of a thiol group, a diacetylene unit and a terminal carboxylic group. The thiol group guarantees preferred binding to the gold nanoparticles surface whereas at the same time the carboxylic group enables electrostatic stabilization. Applying this ligand molecule, gold nanoparticles in the size range of 12-13 nm were prepared. The diacetylene unit was polymerized upon UV irradiation leading to a polymeric ligand shell. Investigations including colloidal stability towards NaCl, DTT displacement reactions, and temperature were performed and indicate an extraordinary high degree of steric and electrostatic stabilization. Individual or at least a few of these particles were immobilized in between nanoelectrodes, thus forming nanoelectronic devices, which were characterized by transport measurements.
- Liffmann,Homberger,Mennicken,Karth?user,Simon
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p. 102981 - 102992
(2015)
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Read Online
- Intramolecular silicon-assisted cross-coupling reactions: General synthesis of medium-sized rings containing a 1,3-cis-cis diene unit
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The combination of ring-closing metathesis and Pd-catalyzed, silicon-assisted intramolecular cross-coupling has been developed to provide an effective and powerful method for construction of medium-sized rings with an internal 1,3-cis-cis diene unit. Allylic alcohols bearing a Z-iodoalkenyl tether can be silylated with chlorodimethylvinylsilane and subjected to Mo-catalyzed ring-closing metathesis to form unsaturated siloxanes. Activation of the siloxane with tetrabutylammonium fluoride in the presence of [allylPdCl]2 leads to high yielding ring-closing reactions to form 9-, 10-, 11- and 12-membered rings. Extension to the synthesis of 9-membered ring unsaturated ethers has also been accomplished. Noteworthy features of this process include: (1) a highly stereospecific intramolecular coupling process, (2) flexible positioning of the hydroxy group, and (3) potential extension to other medium-sized carbocycles and heterocycles. Copyright
- Denmark, Scott E.,Yang, Shyh-Ming
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- Total synthesis of two novel brominated acetylenic diols (+)-diplyne C and E: Stereoselective construction of the (E)-1-bromo-1-alkene
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The total syntheses of the enantiomers of two novel brominated polyacetylenic natural products diplynes C and E are reported. Pd and Cu(I)-catalyzed coupling reactions were employed to synthesize the diyne and enyne units. The stereochemistry of the terminal (E)-alkenyl bromide in diplyne C was constructed stereoselectively using Brown's hydroboration-bromination procedure. The stereochemistry of the internal (E)-double bond in diplyne E was established using a Takai reaction. The stereocenter was derived from d-mannitol.
- Gung, Benjamin W.,Gibeau, Craig,Jones, Amanda
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- On the intramolecular pyrone Diels-Alder approach to basiliolide B
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A unified synthetic approach to the basiliolides/transtaganolides is outlined herein, along with studies illustrating the feasibility of the strategy with respect to the total synthesis of basiliolide B. This work lays the foundation for chemical synthesis of an emerging family of Thapsia metabolites.
- Kozytska, Mariya V.,Dudley, Gregory B.
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- Synthesis of brombyins II and III, cyclostachines A and B, and cyclopiperstachine, plant-derived octahydronaphthalenes
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In this paper we present a study into the direct formation of five plant-derived natural products via intramolecular Diels-Alder cycloaddition of a series of 1,7,9-decatriene precursors. Methods for the preparation of the trienes are also discussed. Georg Thieme Verlag Stuttgart · New York.
- Lygo, Barry,Beaumont, Douglas J.,Cooke, Jason W.B.,Hirst, David J.
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Read Online
- Directed Regioselective Carbometallation of 1,2-Dialkyl-Substituted Cyclopropenes
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A regio- and diastereoselective copper-catalyzed carbomagnesiation of 1,2-dialkylated cyclopropenes is reported. The regioselectivity is controlled by a subtle tethered Lewis basic moiety. The chelating moieties allow the differentiation between two electronically tantamount organometallic intermediates. Further functionalization grants access to polysubstituted stereodefined cyclopropanes bearing up to five alkyl groups.
- Cohen, Yair,Marek, Ilan
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supporting information
p. 26368 - 26372
(2021/11/10)
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- Total Synthesis of a Mycolic Acid from Mycobacterium tuberculosis
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In Mycobacterium tuberculosis, mycolic acids and their glycerol, glucose, and trehalose esters (“cord factor”) form the main part of the mycomembrane. Despite their first isolation almost a century ago, full stereochemical evaluation is lacking, as is a scalable synthesis required for accurate immunological, including vaccination, studies. Herein, we report an efficient, convergent, gram-scale synthesis of four stereo-isomers of a mycolic acid and its glucose ester. Binding to the antigen presenting protein CD1b and T cell activation studies are used to confirm the antigenicity of the synthetic material. The absolute stereochemistry of the syn-methoxy methyl moiety in natural material is evaluated by comparing its optical rotation with that of synthetic material.
- Buter, Jeffrey,Fodran, Peter,Jayaraman, Dhineshkumar,Minnaard, Adriaan J.,Moody, D. Branch,Ocampo, Tonatiuh A.,Tahiri, Nabil,Van Rhijn, Ildiko,Witte, Martin D.
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supporting information
p. 7555 - 7560
(2020/03/23)
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- Total Synthesis of the Tetrasubstituted Furan Fatty Acid Metabolite CeDFP via Au-Catalyzed Intermolecular Alkyne Hydroarylation
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The first total synthesis of the tetrasubstituted furan fatty acid (FFA) metabolite 5-[(1E)-2-carboxyethenyl]-3,4-dimethyl-2-furanpentanoic acid (CeDFP) is reported. CeDFP is a FFA metabolite isolated from shark livers and is related to the known FFA metabolites CMPF and CMPentylF. Key elements of the synthetic route to CeDFP include an iodine-promoted 5-endo-dig cyclization of a 1,2-alkyne diol, a methyllithium-mediated insertion of the C3-methyl group, and a Au(I)-catalyzed intermolecular hydroarylation to introduce the unsaturated ester.
- Wang, Yamin,Pritchard, Gareth J.,Kimber, Marc C.
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supporting information
p. 4892 - 4895
(2019/06/27)
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- Synthesis and Evaluation of a Series of Bis(pentylpyridinium) Compounds as Antifungal Agents
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A series of bis(4-pentylpyridinium) compounds with a variety of spacers between the pyridinium headgroups was synthesised, and the antifungal activity of these compounds was investigated. Lengthening the alkyl spacer between the pentylpyridinium headgroups from 12 to 16 methylene units resulted in increased antifungal activity against C. neoformans and C. albicans, but also resulted in increased hemolytic activity and cytotoxicity against mammalian cells. However, inclusion of an ortho-substituted benzene ring in the centre of the alkyl spacer resulted in decreased cytotoxicity and hemolytic activity, while maintaining antifungal potency. Replacement of the alkyl and aromatic-containing spacers by more hydrophilic ethylene glycol groups resulted in a loss of antifungal activity. Some of the compounds inhibited fungal PLB1 activity, but the low correlation of this inhibition with antifungal potency indicates PLB1 inhibition is unlikely to be the predominant mode of antifungal action of this class of compounds, with preliminary studies suggesting they may act via disruption of fungal mitochondrial function.
- Obando, Daniel,Koda, Yasuko,Pantarat, Namfon,Lev, Sophie,Zuo, Xiaoming,Bijosono Oei, Johanes,Widmer, Fred,Djordjevic, Julianne T.,Sorrell, Tania C.,Jolliffe, Katrina A.
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p. 1421 - 1436
(2018/07/29)
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- Enantioselective Rhodium-Catalyzed Dimerization of ω-Allenyl Carboxylic Acids: Straightforward Synthesis of C2-Symmetric Macrodiolides
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Herein, we report on the first enantioselective and atom-efficient catalytic one-step dimerization method to selectively transform ω-allenyl carboxylic acids into C2-symmetric 14- to 28-membered bismacrolactones (macrodiolides). This convenient asymmetric access serves as an attractive route towards multiple naturally occuring homodimeric macrocyclic scaffolds and demonstrates excellent efficiency to construct the complex, symmetric core structures. By utilizing a rhodium catalyst with a modified chiral cyclopentylidene-diop ligand, the desired diolides were obtained in good to high yields, high diastereoselectivity, and excellent enantioselectivity.
- Steib, Philip,Breit, Bernhard
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supporting information
p. 6572 - 6576
(2018/05/08)
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- Self-assembly and solid-state polymerization of butadiyne derivatives with amide and trialkoxyphenyl groups
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Three butadiyne derivatives with amide and tri(dodecyloxy)-phenyl (TDP) groups were synthesized, and four solidification methods were applied to obtain their self-assembling states in various conditions. The solids obtained were characterized by the solid-state polymerization behaviors, stretching vibration wavenumbers of N-H bonds of amide groups, powder X-ray diffraction, the thermal behaviors, and scanning electron microscope (SEM) observations. We found that all compounds had at least two polymorphs. Property differences between two polymorphs depended on the compounds. Two compounds showed clear differences in UV-vis spectra of the photo-polymerized solids, i.e., the polydiacetylene (PDA) structure, and irregularly polymerized form, or two PDA structures. The remaining compound showed the same PDA absorption but the monomer melting points were different. All compounds gave the gels in various organic solvents because of the molecular design with amide and TDP groups. SEM observation clarified the relationship between gel appearance and the nanostructures.
- Kikuchi, Kohei,Tatewaki, Yoko,Okada, Shuji
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supporting information
p. 298 - 305
(2017/05/10)
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- 5′-Methylene-triazole-substituted-aminoribosyl uridines as MraY inhibitors: synthesis, biological evaluation and molecular modeling
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The straightforward synthesis of 5′-methylene-[1,4]-triazole-substituted aminoribosyl uridines is described. Two families of compounds were synthesized from a unique epoxide which was regioselectively opened by acetylide ions (for compounds II) or azide ions (for compounds III). Sequential diastereoselective glycosylation with a ribosyl fluoride derivative, Cu(i)-catalyzed azide-alkyne cycloaddition (CuAAC) with various complementary azide and alkyne partners afforded the targeted compounds after final deprotection. The biological activity of the 16 resulting compounds together with that of 14 previously reported compounds I, lacking the 5′ methylene group, was evaluated on the MraY transferase activity. Out of the 30 tested compounds, 18 compounds revealed MraY inhibition with IC50 ranging from 15 to 150 μM. A molecular modeling study was performed to rationalize the observed structure-activity relationships (SAR), which allowed us to correlate the activity of the most potent compounds with an interaction involving Leu191 of MraYAA. The antibacterial activity was also evaluated and seven compounds exhibited a good activity against Gram-positive bacterial pathogens with MIC ranging from 8 to 32 μg mL-1, including the methicillin resistant Staphylococcus aureus (MRSA).
- Fer, Micka?l J.,Bouhss, Ahmed,Patr?o, Mariana,Le Corre, Laurent,Pietrancosta, Nicolas,Amoroso, Ana,Joris, Bernard,Mengin-Lecreulx, Dominique,Calvet-Vitale, Sandrine,Gravier-Pelletier, Christine
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p. 7193 - 7222
(2015/07/01)
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- In situ proteome profiling of C75, a covalent bioactive compound with potential anticancer activities
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A library of cell-permeable, minimally tagged C75 analogues was synthesized and used to uncover biological targets in human liver cancer cells. Known targets of C75, namely FASN and CPT1A, together with other unknown targets, including PDIA3, TFRC, and GAPDH, were thus identified.
- Cheng, Xiamin,Li, Lin,Uttamchandani, Mahesh,Yao, Shao Q.
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supporting information
p. 1414 - 1417
(2014/04/03)
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- Identification and synthesis of macrolide pheromones of the grain beetle oryzaephilus surinamensis and the frog spinomantis aglavei
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Macrolide lactones, the so called cucujolides derived from unsaturated fatty acids, are aggregation pheromones of cucujid grain beetles. Thirty years ago, Oehlschlarger etaal. showed that (3Z,6Z)-dodeca-3,6-dien-11-olide (4) and the respective 12-olide (7) attract the sawtoothed grain beetle Oryzaephilus surinamensis, whereas (5Z,8Z,13R)-tetradeca-5,8-dien-13-olide (5) increases the response synergistically. The frass of this beetle is attractive for its parasitoid Cephalonomia tarsalis, which potentially can be used for pest control. A GC/MS analysis of attractive frass showed the presence of 5, together with an unknown isomer. CucujolideaV was tentatively identified also in the femoral glands, pheromone-releasing structures, of the Madagascan mantelline frog Spinomantis aglavei. Therefore, a new route to synthesize doubly unsaturated macrolides allowing the flexible attachment of the side chain was developed. A straightforward method to obtain Zaconfigured macrolides involves ring-closing alkyne metathesis (RCAM) followed by Lindlar-catalyzed hydrogenation. This methodology was extended to homoconjugated diene macrolides by using RCAM after introduction of one Zaconfigured double bond in the precursor by Wittig reaction. A tungsten benzylidyne complex was used as the catalyst in the RCAM reaction, which afforded the products in high yield at room temperature. With the synthetic material at hand, the unknown isomer was identified as the new natural product (5Z,8Z,12R)-tetradeca-5,8-dien-12-olide, cucujolideaX (8). Furthermore, the route also allowed the synthesis of cucujolideaV in good yield. The natural products were identified by the synthesis of enantiomerically pure or enriched material and gas chromatography on chiral phases. The new macrolide (R)-8 proved to be biologically active, attracting female O.asurinamensis, but no males. The synthetic material allowed the identification of (R)-5 in both the beetle and the frog. Attractive synthesis: Females of the sawtoothed grain beetle Oryzaephilus surinamensis are attracted to the new macrolide (5Z,8Z,12R)-tetradeca-5,8-dien-12-olide, cucujolideaX, prepared by using a combination of Wittig reaction and ring-closing alkyne metathesis (RCAM; see scheme). The synthetic approach also allows the synthesis of the similar cucujolideaV, used by both the beetle and the mantellid frog Spinomantis aglavei.
- Hoetling, Susann,Haberlag, Birte,Tamm, Matthias,Collatz, Jana,Mack, Patrick,Steidle, Johannes L. M.,Vences, Miguel,Schulz, Stefan
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supporting information
p. 3183 - 3191
(2014/03/21)
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- Cyclization of gold acetylides: Synthesis of vinyl sulfonates via gold vinylidene complexes
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Differently substituted terminal alkynes that bear sulfonate leaving groups at an appropriate distance were converted in the presence of a propynyl gold(I) precatalyst. After initial formation of a gold acetylide, a cyclization takes place at the β-carbon atom of this species. Mechanistic studies support a mechanism that is related to that of dual gold-catalyzed reactions, but for the new substrates, only one gold atom is needed for substrate activation. After formation of a gold vinylidene complex, which forms a tight contact ion pair with the sulfonate leaving group, recombination of the two parts delivers vinyl sulfonates, which are valuable targets that can serve as precursors for cross-coupling reactions, for example. Gold vinylidene intermediates are generated by the cyclization of gold acetylides that carry a sulfonate leaving group. This result demonstrates for the first time that the formation of these species is not restricted to a dual activation mode. The cyclization products obtained herein contain a vinyl sulfonate moiety, which makes them useful building blocks for cross-coupling reactions.
- Bucher, Janina,Wurm, Thomas,Nalivela, Kumara Swamy,Rudolph, Matthias,Rominger, Frank,Hashmi, A. Stephen K.
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supporting information
p. 3854 - 3858
(2014/05/06)
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- Temporally controlled targeting of 4-hydroxynonenal to specific proteins in living cells
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In-depth chemical understanding of complex biological processes hinges upon the ability to systematically perturb individual systems. However, current approaches to study impacts of biologically relevant reactive small molecules involve bathing of the entire cell or isolated organelle with excess amounts, leading to off-target effects. The resultant lack of biochemical specificity has plagued our understanding of how biological electrophiles mediate signal transduction or regulate responses that confer defense mechanisms to cellular electrophilic stress. Here we introduce a target-specific electrophile delivery platform that will ultimately pave the way to interrogate effects of reactive electrophiles on specific target proteins in cells. The new methodology is demonstrated by photoinducible targeted delivery of 4-hydroxynonenal (HNE) to the proteins Keap1 and PTEN. Covalent conjugation of the HNE-precursor to HaloTag fused to the target proteins enables directed HNE delivery upon photoactivation. The strategy provides proof of concept of selective delivery of reactive electrophiles to individual electrophile-responsive proteins in mammalian cells. It opens a new avenue enabling more precise determination of the pathophysiological consequences of HNE-induced chemical modifications on specific target proteins in cells.
- Fang, Xinqiang,Fu, Yuan,Long, Marcus J. C.,Haegele, Joseph A.,Ge, Eva J.,Parvez, Saba,Aye, Yimon
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supporting information
p. 14496 - 14499
(2013/10/22)
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- Fused ring aziridines as a facile entry into triazole fused tricyclic and bicyclic heterocycles
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The intramolecular dipolar cycloaddition of an azide with an alkyne has provided a useful entry into triazole fused tricyclic heterocycles containing both the triazole ring and the oxazolidin-2-one ring system. The requisite azido-alkynes have been prepared via a two-step sequence from fused ring aziridines. A series of 6-12 membered rings containing both the oxazolidinone and triazole rings have been prepared. These ring systems have been designed as conformationally restrained analogs of RNA-binding oxazolidinones. The Royal Society of Chemistry 2012.
- Fang, Fang,Vogel, Megan,Hines, Jennifer V.,Bergmeier, Stephen C.
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scheme or table
p. 3080 - 3091
(2012/05/07)
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- A thermal dehydrogenative Diels-Alder reaction of styrenes for the concise synthesis of functionalized naphthalenes
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Functionalized naphthalenes are valuable building blocks in many important areas. A microwave-assisted, intramolecular dehydrogenative Diels-Alder reaction of styrenyl derivatives to provide cyclopenta[b]naphthalene substructures not previously accessible using existing synthetic methods is described. The synthetic utility of these uniquely functionalized naphthalenes was demonstrated by a single-step conversion of one of these cycloadducts to a fluorophore bearing a structural resemblance to Prodan.
- Kocsis, Laura S.,Benedetti, Erica,Brummond, Kay M.
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supporting information
p. 4430 - 4433
(2012/10/29)
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- Metal-catalyzed syntheses of abridged CDE rings of rubriflordilactones A and B
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The development of complementary palladium- and cobalt-catalyzed approaches to tricyclic arylsilanes suitable for elaboration into the CDE ring systems of rubriflordilactones A and B is reported. Microwave conditions are required to effect a cobalt-catalyzed triyne cyclotrimerization, which critically depends on the substitution pattern of the triyne termini. Mild conditions to elaborate these arylsilanes to the CDE cores of the natural products are described.
- Goh, Shermin S.,Baars, Hannah,Gockel, Birgit,Anderson, Edward A.
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supporting information
p. 6278 - 6281
(2013/02/23)
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- Polyunsaturated alkyl amides from echinacea: Synthesis of diynes, enynes, and dienes
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The synthesis of 20 alkyl amides, including 15 naturally occurring polyunsaturated alkyl amides previously identified from Echinacea spp. (1-13 and 62) or from Achilla sp. (55) and five previously unknown geometric isomers (23, 28, 67, 73, and 80), is described. Importantly, these amides include all of the major alkyl amides present in commercially used Echinacea extracts. The syntheses demonstrate methodology used for constructing alkyl amides containing conjugated diyne and isomerically pure enyne and diene moieties and may be adapted easily for the preparation of other alkyl amides present in Echinacea spp. Terminal-conjugated diynes were prepared by a Cadiot-Chodkiewitz coupling/deprotection sequence utilizing a protected bromoacetylene, and methyl-substituted diynes were made via a base-catalyzed rearrangement of terminal-skipped diynes. Conjugated dienes were prepared conveniently and with high stereoselectivity by the reduction of enynes or diynes with Rieke zinc. With the exception of 1-2 and 11-12, the alkyl amides are synthesized here for the first time, and their NMR data are consistent with that of the reported isolated natural compounds.
- Matovic, Nicholas J.,Hayes, Patricia Y.,Penman, Kerry,Lehmann, Reginald P.,De Voss, James J.
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p. 4467 - 4481
(2011/07/30)
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- Synthesis and functional pharmacological effects on human bronchi of 20-hydroxyeicosatetraenoic acid
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We have synthesized 20-hydroxyeicosatetraenoic acid (20-HETE) following a new route and delineated its functional effects in human bronchi. Isometric tension measurements were performed, and they demonstrated that synthetic 20-HETE induced a concentration-dependent relaxant effect in ASM on resting tone and on bronchi pre-contracted with methacholine.
- Proteau-Gagne,St-Jean,Morin,Gendron,Rousseau,Dory
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experimental part
p. 841 - 847
(2011/04/25)
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- Assignment of the structure of petrocortyne A by mixture syntheses of four candidate stereoisomers
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Two different mixture synthesis routes have been used to make the four stereoisomers of petrocortyne A. A first quick and dirty route provided a mixture of the four isomers in nonselective fashion. Mosher and 2-naphthylmethoxyacetic acid (NMA) ester methods were developed to identify the components, and the mixture was partially resolved on analytical chiral HPLC to give the two pure enantiomers of petrocortyne A and the racemate of its diastereomer. A second fluorous mixture synthesis produced all four isomers of petrocortyne A in individual pure form. Comparison of spectra of Mosher derivatives of the synthetic isomers with two supposedly different natural products showed that both natural samples were instead identical and had the (3S,14S) configuration. Likewise, petrocortynes B, D, and F-H are (3S,14S) and petrocortyne D is (3R,14S). Having access to all possible candidate isomers of both petrocortyne A and its Mosher derivatives provided a secure structure assignment not so much because one of the isomers matched the natural product, but because all of the other isomers did not.
- Sui, Bin,Yeh, Edmund A.-H.,Curran, Dennis P.
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supporting information; experimental part
p. 2942 - 2954
(2010/07/17)
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- Structural-based design and synthesis of novel 9-deazaguanine derivatives having a phosphate mimic as multi-substrate analogue inhibitors for mammalian PNPs
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9-(5′,5′-Difluoro-5′-phosphonopentyl)-9-deazaguanine (DFPP-DG) was designed as a multi-substrate analogue inhibitor against purine nucleoside phosphorylase (PNP) on the basis of X-ray crystallographic data obtained for a binary complex of 9-(5′,5′-difluoro-5′-phosphonopentyl)guanine (DFPP-G) with calf-spleen PNP. DFPP-DG and its analogous compounds were synthesized by the Sonogashira coupling reaction between a 9-deaza-9-iodoguanine derivative and ω-alkynyldifluoromethylene phosphonates as a key reaction. The experimental details focused on the synthetic chemistry along with some insights into the physical and biological properties of newly synthesized DFPP-DG derivatives are disclosed.
- Hikishima, Sadao,Hashimoto, Mariko,Magnowska, Lucyna,Bzowska, Agnieszka,Yokomatsu, Tsutomu
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supporting information; experimental part
p. 2275 - 2284
(2010/05/17)
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- Synthesis and activity of polyacetylene substituted 2-hydroxy acids, esters, and amides against microbes of clinical importance
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A series of novel polyacetylene substituted 2-hydroxy acids and derivatives were prepared and characterized. Alkylation of butane-2,3-diacetal (BDA) protected glycolic acid with iodoalkyl substituted polyacetylene compounds gave the corresponding diacetal protected polyacetylene substituted 2-hydroxy acids. Diacetal deprotection through acid mediated hydrolysis, transesterification or aminolysis afforded the 2-hydroxy-polyacetylenic acid, ester or amide derivatives. Twenty one of these novel compounds were tested against 10 microbes of clinical importance and several of them showed good antimicrobial activity, in particular against Pseudomonas aeruginosa.
- Kyi, Stella,Wongkattiya, Nalin,Warden, Andrew C.,O'Shea, Michael S.,Deighton, Margaret,MacReadie, Ian,Graichen, Florian H.M.
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supporting information; experimental part
p. 4555 - 4557
(2010/09/16)
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- Indium(III)-catalyzed coupling between alkynes and aldehydes to α,β-unsaturated ketones
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The combined use of a catalytic amount of InX3 (X = OTf and NTf2) and 1-butanol was found to be effective in formal alkynealdehyde metathesis. With this catalytic system, aromatic alkynes reacted with aromatic aldehydes to give chalcones in moderate to good yields. Alkynals were efficiently converted into 5- to 7-membered cyclic compounds by intramolecular alkyne-aldehyde coupling.
- Miura, Katsukiyo,Yamamoto, Kiyomi,Yamanobe, Aya,Ito, Keisuke,Kinoshita, Hidenori,Ichikawa, Junji,Hosomi, Akira
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supporting information; experimental part
p. 766 - 767
(2011/01/09)
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- The scope and limitations of intramolecular Nicholas and Pauson-Khand reactions for the synthesis of tricyclic oxygen-and nitrogen-containing heterocycles
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(Chemical Equation Presented) We studied the scope and limitations of a tandem intramolecular Nicholas/Pauson-Khand strategy for the synthesis of tricyclic oxygen- and nitrogen-containing heterocycles. This methodology enables conversion of simple acyclic starting materials into a series of previously unknown heterocyclic architectures. For the preparation of cyclic ethers (Z = O), tricyclic [5,6,5]- through [5,9,5]-systems (m = 1, n = 1-4) are available with the [5,7,5]- and [5,8,5]-systems amenable to quick and efficient synthesis. Tricyclic [5,7,5]- and [5,8,5]-amine-containing (Z = NTs) heterocycles can be successfully prepared. Attempts to make larger ring systems (Z = O, m = 2; Z = O, n = 5; or Z = NTs, n = 4-5) or prepare lactones via Nicholas reactions with carboxylic acid nucleophiles (available via oxidation of alcohol nucleophiles, Z = O) result in decomposition or dimerization. The latter process enables formation of 14-, 16-, and 18-membered ring diolides when using carboxylic acid nucleophiles. We also investigated the use of chiral amine promoters in the Pauson-Khand step but found no asymmetric induction.
- Closser, Kristina D.,Quintal, Miriam M.,Shea, Kevin M.
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scheme or table
p. 3680 - 3688
(2009/10/02)
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- CONJUGATED UNSATURATED COMPOUNDS
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The present invention relates to a class of conjugated unsaturated compounds, to a method of preparing such compounds, and to the polymerisation and bio-active uses of such compounds including their use as antimicrobial agents. The invention particularly relates to compounds containing three conjugated unsaturated moieties, at least two of which are yne moieties.
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Page/Page column 62
(2009/10/22)
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- Enantioselective synthesis of Anomala osakana pheromone and Janus integer pheromone: A flexible approach to chiral γ-butyrolactones
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The enantioselective synthesis of Anomala osakana pheromone and Janus integer pheromone has been achieved without using any protecting groups. The synthesis involved using an asymmetric alkynylation to obtain γ-hydroxy-α,β-acetylenic esters with high ee (84%) and yields (～80%), followed by selective hydrogenation and lactonization in high overall yields (87% and 89%).
- Lin, Li,Zhao, Qiangyang,Li, A-Ni,Ren, Fengbo,Yang, Fanzhi,Wang, Rui
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supporting information; experimental part
p. 3663 - 3665
(2009/10/23)
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- SPHINGOSINE-1 -PHOSPHATE RECEPTOR AGONIST AND ANTAGONIST COMPOUNDS
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The present invention is directed to novel, potent, and selective agents, which are agonists or antagonists of the one or more of the individual receptors of the S1P receptor family. The compounds of the invention are useful as therapeutics for treating medical conditions associated with agonism or antagonism of the individual receptors of the S1P receptor family.
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Page/Page column 126
(2008/12/07)
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- De novo formal synthesis of (-)-apicularen A via an iterative asymmetric hydration sequence
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(Chemical Equation Presented) A de novo approach to the formal total synthesis of the macrolide natural product (-)-apicularen A has been achieved in 18 steps'from achiral starting materials. Both the absolute and relative stereochemistries of apicularen A were introduced by a Sharpless asymmetric dihydroxylation, a π-allyl-palladium catalyzed reduction, a stereoselective reduction, and a base-promoted transannulation to install the C-9 stereocenter.
- Li, Miaosheng,O'Doherty, George A.
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p. 6087 - 6090
(2007/10/03)
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- Tandem nucleophilic addition/fragmentation reactions and synthetic versatility of vinylogous acyl triflates
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A thorough analysis of the chemistry of vinylogous acyl triflates provides insight into important chemical processes and opens new directions in synthetic technology. Tandem nucleophilic addition/C-C bond cleaving fragmentation reactions of cyclic vinylogous acyl triflates 1 yield a variety of acyclic acetylenic compounds. Full details are disclosed herein. A wide array of nucleophiles, such as organolithium and Grignard reagents, lithium enolates and their analogues, hydride reagents, and lithium amides, are applied. The respective reactions produce ketones 2, 1,3-diketones and their analogues 3, alcohols 4, and amides 5. The present reactions are proposed to proceed through a 1,2-addition of the nucleophile to the carbonyl group of starting triflates 1 to form tetrahedral alkoxide intermediates C, followed by Grob-type fragmentation, which effects C-C bond cleavage to yield acyclic acetylenic compounds 2-5 and 7. The potent nucleofugacity of the triflate moiety is channeled through the σ-bond framework of 1, providing direct access to the fragmentation pathway without denying other typical reactions of cyclic vinylogous esters. The synthetic versatility of vinylogous acyl triflates, including functionalization reactions of the cyclic enone core (1 → 6 or 8), is also illustrated.
- Kamijo, Shin,Dudley, Gregory B.
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p. 6499 - 6507
(2007/10/03)
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- In situ selection of lead compounds by click chemistry: Target-guided optimization of acetylcholinesterase inhibitors
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The target-guided, in situ click chemistry approach to lead discovery has been successfully employed for discovering acetylcholinesterase (AChE) inhibitors by incubating a selected enzyme/tacrine azide combination with a variety of acetylene reagents that were not previously known to interact with the enzyme's peripheral binding site. The triazole products, formed by the enzyme, were identified by HPLC-mass spectrometry analysis of the crude reaction mixtures. The target-guided lead discovery search was also successful when performed with reagent mixtures containing up to 10 components. From 23 acetylene reagents, the enzyme selected two phenyltetrahydroisoquinoline (PIQ) building blocks that combined with the tacrine azide within the active center gorge to form multivalent inhibitors that simultaneously associate with the active and peripheral binding sites. These new inhibitors are up to 3 times as potent as our previous phenylphenanthridinium-derived compounds, and with dissociation constants as low as 33 femtomolar, they are the most potent noncovalent AChE inhibitors known. In addition, the new compounds lack a permanent positive charge and aniline groups and possess fewer fused aromatic rings. Remarkably, despite the high binding affinity, the enzyme displayed a surprisingly low preference for one PIQ enantiomer over the other.
- Krasinski, Antoni,Radic, Zoran,Manetsch, Roman,Raushel, Jessica,Taylor, Palmer,Sharpless, K. Barry,Kolb, Hartmuth C.
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p. 6686 - 6692
(2007/10/03)
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- Synthesis of medium- and large-sized lactones in an aqueous-organic biphasic system
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(Chemical Equation Presented) Saving solvent: An aqueous-ethyl acetate biphasic system allows an efficient synthesis of medium- and large-sized lactones by an intramolecular Tsuji-Trost reaction (see scheme, n = 1-5). The macrocyclization protocol does not require a large quantity of solvents or a slow-addition technique.
- Kinoshita, Hidenori,Shinokubo, Hiroshi,Oshima, Koichiro
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p. 2397 - 2400
(2007/10/03)
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- Synthesis of ynamides
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A method of synthesizing diacetylenic amides is described. The key steps of the invention include the reaction of an aldehyde with the monoanion of a diacetylene and the reductive removal of a propargylic alcohol. The invention offers the first known method of synthesizing diacetylenic amides that are naturally isolated from Echinacea through a direct and flexible route.
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Page/Page column 3
(2008/06/13)
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- Development of an Efficient Procedure for Indole Ring Synthesis from 2-Ethynylaniline Derivatives Catalyzed by Cu(II) Salts and Its Application to Natural Product Synthesis
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The development of efficient methods for the indole synthesis catalyzed by Cu(II) salts and its applications were investigated. Cu(OAc)2 has been proved to be the best catalyst for the synthesis of various 1-p-tolylsulfonyl or 1-methylsulfonylindoles, which have both electron-withdrawing and electron-donating groups on the aromatic ring and C2 position of indoles. For the primary aniline derivatives, Cu(OCOCF 3)2 showed good activities, while Cu(OAc)2 was a good catalyst for the cyclization of secondary anilines. This methodology could be applied to the sequential cyclization reaction for the compounds which have the electrophilic part in the same molecule. By prior treatment with KH, the sequential cyclization was realized to provide the tricyclic ring systems, but it was limited to five- and six-membered rings for the second cyclization. Finally, formal and total synthesis of hippadine with the Cu(II)-promoted indole synthesis as the key step was accomplished.
- Hiroya, Kou,Itoh, Shin,Sakamoto, Takao
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p. 1126 - 1136
(2007/10/03)
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- Sequential ring-closing metathesis/Pd-catalyzed, Si-assisted cross-coupling reactions: General synthesis of highly substituted unsaturated alcohols and medium-sized rings containing a 1,3-cis-cis diene unit
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A sequential ring-closing metathesis/silicon-assisted cross-coupling protocol has been developed. Alkenyldimethylsilyl ethers of allylic, homoallylic and bis(homoallylic) alcohols undergo facile ring closure with Schrock's catalyst to afford 5-, 6-, and 7-membered cycloalkenylsiloxanes, respectively, in some cases with substituents on both alkenyl carbons. These siloxanes are highly effective coupling partners that afford styrenes and dienes (with various aryl and alkenyl halides) in high yield and specificity as well as good functional group compatibility. The siloxanes bearing a Z-iodoalkenyl tether undergo an intramolecular coupling process in the presence of [allylPdCl] 2 which constitutes a powerful method for the construction of medium-sized rings with an internal 1,3-cis-cis diene unit. The formation of 9-, 10-, 11-, and 12-membered carbocyclic dienes is achieved in good yield. Extension to the synthesis of 9-membered ring unsaturated ethers has also been accomplished. Noteworthy features of this process include: (1) highly stereospecific intramolecular coupling, (2) flexible positioning of the revealed hydroxy group, and (3) potential extension to other medium-sized carbocycles and heterocycles. Graphical Abstract.
- Denmark, Scott E.,Yang, Shyh-Ming
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p. 9695 - 9708
(2007/10/03)
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- Applications of size-selective macrolactonizations to the synthesis of benzolactone-enamide core structures
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By utilizing Stille cross-coupling reactions four benzoic acid derivatives (18, 32, 46, 66) were prepared that carry a side chain with two secondary hydroxy groups. It could be shown that the hydroxy functions can be distinguished by size-selective macrolactonization reactions. Thus, 12-membered lactones 19 and 33 are favored over their 11-membered lactone counterparts 20 and 34, respectively, albeit with a low (60:40-70:30) ratio. The selectivity is much more pronounced if there is a competition between a 12- and 10-membered lactone. This could be shown with the two lactones 47 and 67. The 12-membered lactones 33, 47, and 67 represent core structures for analogs of the benzolactone enamides. The macrolactonization reactions were performed under Yamaguchi conditions.
- Petri, Andreas F.,Kuehnert, Sven M.,Scheufler, Frank,Maier, Martin E.
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p. 940 - 955
(2007/10/03)
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- Synthesis of (15S,16S,21R)-4-deoxyrollicosin analog
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Synthesis of 4-deoxy rollicosin analog 2 was completed in nine steps, which was based on palladium-catalyzed coupling of two building blocks 3 and 4. Lactone 3 was synthesized from 5-hexyn-1-ol, and vinyl iodide 4 was accessed from L-glutamate and 1-hexyne.
- Lee, Jeng-Lin,Lin, Chi-Fong,Hsieh, Ling-Yu,Lin, Wan-Ru,Chiu, Huey-Fen,Wu, Yang-Chang,Wang, Kun-Sheng,Wu, Ming-Jung
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p. 7833 - 7835
(2007/10/03)
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- Preparation and cancer cell invasion inhibitory effects of C16-alkynic fatty acids.
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Five C(16)-alkynic fatty acids (2-6) were prepared and examined their inhibitory effects on cancer cell invasion. It has been found that hexadeca-6,8,10-triynoic acid (5) and hexadeca-8,10,12-triynoic acid (6) exhibit similar potent inhibitory activities with that of octadeca-8,10,12-triynoic acid (1) which was isolated from Scurrula atropurpurea (Loranthaceae).
- Ohashi, Kazuyoshi,Winarno, Hendig,Mukai, Mutsuko,Shibuya, Hirotaka
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p. 463 - 466
(2007/10/03)
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- Study of the regioselectivity in the hydrotelluration of hydroxy alkynes
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Vinylic tellurides were synthesized by the addition of organotellurols to acetylenic alcohols and the regioselectivity of the reaction was evaluated.
- Stefani, Hélio A.,Cardoso, Lincoln D. G.,Valduga, Claudéte J.,Zeni, Gilson
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p. 167 - 172
(2007/10/03)
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- endo-selective intramolecular Pauson - Khand reactions of γ-oxygenated-αβ-unsaturated phenylsulfones
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A wide variety of 1,6-enynes and 1,7-enynes incorporating γ-oxygenated-α,β-unsaturated phenylsulfone moieties have readily been prepared by piperidine-promoted condensation of the corresponding alkynyl aldehyde with phenylsulfonyl-(p-tolylsulfinyl)methane and further protection of the hydroxyl group. Despite the enduring claim concerning the unsuitability of electronically deficient olefins in Pauson - Khand reactions, we report that these 1-sulfonylated enynes are excellent substrates in intramolecular Pauson - Khand reactions under both thermal and amine N-oxide-promoted conditions. Moreover, in contrast with the usual exo-selective Pauson - Khand cyclization of allylic substituted enynes, the reactions of these 1-sulfonylated-3-oxygenated enynes occur with a moderate or high endo selectivity. The evaluation of the chemical and stereochemical scope of the process in comparison with the Pauson - Khand cyclization of non-sulfonylated enynes, its application to the stereo-selective preparation of optically pure C6-substituted bicyclo[3.3.0]oct-1-en-3-ones, and the interpretation of the stereochemical outcome are also discussed.
- Adrio, Javier,Rivero, Marta Rodrguez,Carretero, Juan C.
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p. 2435 - 2448
(2007/10/03)
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- Synthesis of a model system for the macrocyclic subunit of the oximidines
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Cross-coupling reaction of aryl triflate 1 and vinyl stannane 13 provided salicylic acid derivative 15. This compound was converted to the dihydroxy acid 16, which provided in a size-selective macrolactonization the two macrolides 17 and 18 in a ratio of 60:40. Compound 17 is a model of the macrocyclic core of the oximidines.
- Scheufler,Maier
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p. 1221 - 1224
(2007/10/03)
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- Synthesis of cyclo-1,3-dien-5-ynes
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Cyclo-1,3-dien-5-ynes with ring sizes from 10 to 14 (6a-e) have been prepared for the first time by using a five-step synthesis starting from the alkynols 7a-e. The final ring-closure was achieved by McMurry coupling of the α,ω-dialdehydes 12a-e with the complex TiCl3(DME)1.5. Thermal isomerization of the cyclodienynes leads to the corresponding benzocycloalkenes, and it has been shown that the ring size has a considerable influence on the temperature necessary for thermocylization.
- Hopf, Henning,Krueger, Anke
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p. 4378 - 4385
(2007/10/03)
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- Synthesis of polyacetylenic acids isolated from Heisteria acuminata
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matrix presented Four linear polyacetylenic compounds were synthesized. Pentadeca-6,8,10-triynoic acid 1 and octadeca-8,10,12-triynoic acid 2 were synthesized by using acetylene coupling reactions. The syntheses of (Z)-hexadec-11-en-7,9-diynoic acid 3 and (Z)-octadec-12-en-7,9-diynoic acid 4 by using vinylic telluride coupling reactions were accomplished.
- Zeni, Gilson,Panatieri, Rodrigo B.,Lissner, Eliseo,Menezes, Paulo H.,Braga, Antonio L.,Stefani, Helio A.
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p. 819 - 820
(2007/10/03)
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- Novel 1,3-diene synthesis from alkyne and ethylene by ruthenium- catalyzed enyne metathesis
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A novel 1,3-diene synthetic method from alkyne and ethylene was developed using ruthenium-catalyzed enyne metathesis. The reaction procedure is very simple: A CH2Cl2 solution of alkyne was stirred at room temperature under ethylene gas (1 atm.) in the presence of a catalytic amount of ruthenium benzylidene complex. The yield was good and the conversion yield was high. Dienes having functional groups such as a keto-carbonyl group, silyloxy group, ester, and ketal were synthesized from the corresponding alkynes and ethylene. In this reaction, the alkyne having a hetero atom at the propargylic position gave a good result and ether oxygen or amine nitrogen that coordinate strongly to the ruthenium catalyst prevents the reaction.
- Kinoshita, Atsushi,Sakakibara, Norikazu,Mori, Miwako
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p. 8155 - 8167
(2007/10/03)
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- The first synthesis of tonkinecin, an annonaceous acetogenin with a C-5 carbinol center
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(formula presented) Reported herein is the first synthetic approach to tonkinecin (1) which uses a palladium-catalyzed cross-coupling reaction between the tetrahydrofuran unit (4) and the butenolide (3) as the key step for constructing the backbone of 1. The stereogenic centers at C-5, C-21, C-22, and C-36 were derived from D-xylose, D-glucose, and L-lactate, respectively, whereas those at C-17, and C-18 were generated using Sharpless asymmetric dihydroxylation.
- Hu, Tai-Shan,Yu, Qian,Lin, Qi,Wu, Yu-Lin,Wu, Yikang
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p. 399 - 401
(2008/02/11)
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- The total synthesis of 20-hydroxyhepoxilins A3, new metabolites of the hepoxilin family of eicosanoids
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An enantiodirected total synthesis of 20-hydroxyhepoxilins A3, new eicosanoids of the lipoxygenase metabolism of arachidonic acid, was perfomed. The synthetic samples were found to be identical to the major metabolite formed upon incubation of (85)-hepoxilin A3 with human neutrophiles, which demonstrated that it has the structure of (8S)-20-hydroxy-HxA3.
- Demin,Kochev,Manukina,Pace-Asciak,Pivnitsky
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p. 692 - 699
(2007/10/03)
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- Mirabimide E, an unusual N-acylpyrrolinone from the blue-green alga Scytonema mirabile: Structure determination and synthesis
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Mirabimide E, a solid tumor selective cytotoxin from the terrestrial blue-green alga Scytonema mirabile UH strain BY-8-1, possesses an unprecedented tetrachlorinated ethylene group and has been identified as (5S,2'R,3'R)N-(anti-8',8',9',9'-tetrachloro-3'-(carbamoyloxy)-2'-methy ldecanoyl)-4-methoxy-5-methyl-3-pyrrolin-2-one. The total structure, including absolute stereochemistry, of this novel N-acylpyrrolinone was concluded from a combination of spectral and chemical studies, including stereoselective syntheses of three degradation products, viz. methyl (2R,3R)anti-8,8,9,9-tetrachloro-3-hydroxy-2-methyldecanoate, (5R,6R)-trans-5-methyl-6-(5,5',6,6'-tetrachloroheptyl)-1-oxa-3-azacycl ohexane-2,4-dione, and (5S)-4-methoxy-5-methyl-3-pyrrolin-2-one, and the total synthesis of mirabimide E itself. The influence of the carbamate ester group on the chemical degradation and synthesis of mirabimide E is described.
- Paik, Seunguk,Carmeli, Shmuel,Cullingham, Jean,Moore, Richard E.,Patterson, Gregory M. L.,Tius, Marcus A.
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p. 8116 - 8125
(2007/10/02)
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