- 1,2-Carbopentafluorophenylation of Alkynes: The Metallomimetic Pull-Push Reactivity of Tris(pentafluorophenyl)borane
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We report the novel single-step 1,2-dicarbofunctionalization of an arylacetylene with an allylsilane and tris(pentafluorophenyl)borane [B(C6F5)3] involving C?C bond formation with C?H bond scission at the β-position to the silicon atom of an allylsilane and B→C migration of a C6F5 group. The 1,2-carbopentafluorophenylation occurs smoothly without the requirement for a catalyst or heating. Mechanistic studies suggest that the metallomimetic “pull-push” reactivity of B(C6F5)3 imparts consecutive electrophilic and nucleophilic characteristics to the benzylic carbon of the arylacetylene. Subsequent photochemical 6π-electrocyclization affords tetrafluoronaphthalenes, which are important in the pharmaceutical and materials sciences. Owing to the unique reactivity of B(C6F5)3, the 1,2-carbopentafluorophenylation using 2-substituted furan proceeded with ring opening, and the reaction using silyl enolates formed a C?C bond with C?O bond scission at the silyloxy-substituted carbon.
- Shibuya, Masatoshi,Matsuda, Miki,Yamamoto, Yoshihiko
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supporting information
p. 8822 - 8831
(2021/05/21)
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- Photocatalyzed E→Z Contra-thermodynamic Isomerization of Vinyl Boronates with Binaphthol
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The photocatalytic contra-thermodynamic E→Z isomerization of vinyl boronates by using a binaphthol catalyst is disclosed. The reaction, based on the transient formation of a suitable chromophore with a BINOL derivative as the catalyst, allowed geometrical isomerization in good-to-excellent Z/E ratio and excellent-to-quantitative yields. The mechanism of this E→Z contra-thermodynamic isomerization was studied, and the formation of a transient chromophore species is suggested.
- Brégent, Thibaud,Bouillon, Jean-Philippe,Poisson, Thomas
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p. 13966 - 13970
(2021/08/25)
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- Pd/Cu-Catalyzed Vinylation of Terminal Alkynes with (2-Bromoethyl)diphenylsulfonium Triflate
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The potential of (2-bromoethyl)diphenylsulfonium triflate to be a powerful vinylation reagent was determined by the Sonogashira cross-coupling reactions with terminal alkynes. The vinylation proceeded smoothly at 25 °C under Pd/Cu catalysis to afford a variety of 1- and 2-unsubstituted 1,3-enynes in moderate to excellent yields. This protocol represents the first application of (2-haloethyl)diphenylsulfonium triflate as a CH═CH2 transfer source in organic synthesis.
- Ming, Xiao-Xia,Wu, Shuai,Tian, Ze-Yu,Song, Jia-Wei,Zhang, Cheng-Pan
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p. 6795 - 6800
(2021/09/08)
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- SO2F2-Mediated Oxidative Dehydrogenation and Dehydration of Alcohols to Alkynes
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Direct synthesis of alkynes from inexpensive, abundant alcohols was achieved in high yields (greater than 40 examples, up to 95% yield) through a SO2F2-promoted dehydration and dehydrogenation process. This straightforward transformation of sp3-sp3 (C-C) bonds to sp-sp (C=C) bonds requires only inexpensive and readily available reagents (no transition metals) under mild conditions. The crude alkynes are sufficiently free of impurities to permit direct use in further transformations, as illustrated by regioselective Huisgen alkyne-azide cycloaddition reactions with PhN3 to give 1,4-substituted 1,2,3-traiazoles (16 examples, up to 92% yield) and Sonogashira couplings (10 examples, up to 77% yield).
- Zha, Gao-Feng,Fang, Wan-Yin,Li, You-Gui,Leng, Jing,Chen, Xing,Qin, Hua-Li
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supporting information
p. 17666 - 17673
(2019/01/04)
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- How Large Can We Build a Cyclic Assembly? Impact of Ring Size on Chelate Cooperativity in Noncovalent Macrocyclizations
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Self-assembled systems rely on intramolecular cooperative effects to control their growth and regulate their shape, thus yielding discrete, well-defined structures. However, as the size of the system increases, cooperative effects tend to dissipate. We analyze here this situation by studying a set of oligomers of different lengths capped with guanosine and cytidine nucleosides, which associate in cyclic tetramers by complementary Watson–Crick H-bonding interactions. As the monomer length increases, and thus the number of C(sp)–C(sp2) σ-bonds in the π-conjugated skeleton, the macrocycle stability decreases due to a notable reduction in effective molarity (EM), which has a clear entropic origin. We determined the relationship between EM or ΔS and the number of σ-bonds, which allowed us to predict the maximum monomer lengths at which cyclic species would still assemble quantitatively, or whether the cyclic species would not able to compete at all with linear oligomers over the whole concentration range.
- Montoro-García, Carlos,Mayoral, María J.,Chamorro, Raquel,González-Rodríguez, David
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p. 15649 - 15653
(2017/12/02)
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- Mn-catalyzed aromatic C-H alkenylation with terminal alkynes
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The first manganese-catalyzed aromatic C-H alkenylation with terminal alkynes is described. The procedure features an operationally simple catalyst system containing commercially available MnBr(CO)5 and dicyclohexylamine (Cy2NH). The reaction occurs readily in a highly chemo-, regio-, and stereoselective manner delivering anti-Markovnikov E-configured olefins in high yields. Experimental study and DFT calculations reveal that (1) the reaction is initiated by a C-H activation step via the cooperation of manganese and base; (2) manganacycle and alkynylmanganese species are the key reaction intermediates; and (3) the ligand-to-ligand H-transfer and alkynyl-assisted C-H activation are the key steps rendering the reaction catalytic in manganese.
- Zhou, Bingwei,Chen, Hui,Wang, Congyang
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p. 1264 - 1267
(2013/03/14)
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- Supramolecular hierarchy among halogen-bond donors
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Through a combination of structural chemistry, vibrational spectroscopy, and theory, we have systematically examined the relative structure-directing importance of a series of ditopic halogen-bond (XB) donors. The molecular electrostatic potential surfaces of six XB donors were evaluated, which allowed for a charge-based ranking. Each molecule was then co-crystallized with 21 XB acceptors and the results have made it possible to map out the supramolecular landscape describing the competition between I/Br-ethynyl donors, perfluorinated I/Br donors, and I/Br-phenyl based donors. The results offer practical guidelines for synthetic crystal engineering driven by robust and directional halogen bonds. Copyright
- Aakeroey, Christer B.,Baldrighi, Michele,Desper, John,Metrangolo, Pierangelo,Resnati, Giuseppe
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p. 16240 - 16247
(2013/12/04)
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- Synthesis of biaryl derivatives by using ruthenium-mediated [2+2+2] cyclotrimerization and Suzuki-Miyaura cross-coupling as key steps
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Functionalized biaryl derivatives have been prepared by applying [2+2+2] cyclotrimerization with the aid of Grubbs first-generation catalyst (G-I). The trimerized products were subjected to the Suzuki-Miyaura cross-coupling reaction sequence to generate h
- Kotha, Sambasivarao,Seema, Vittal,Mobin, Shaikh M.
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scheme or table
p. 1581 - 1586
(2011/06/25)
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- BF3×OEt2-catalyzed reaction of donor-acceptor cyclobutanes with terminal alkynes: Single-step access to 2,3-dihydrooxepines
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In the presence of BF3OEt2 cyclobutane-1,1-diesters undergo a reaction with terminal alkynes to quickly access dihydro-oxepines. Georg Thieme Verlag Stuttgart · New York.
- MacHin, Ben P.,Pagenkopf, Brian L.
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supporting information; experimental part
p. 2799 - 2802
(2012/01/11)
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- Diversity-oriented synthesis of biaryl derivatives using cross-enyne metathesis, diels-alder reaction, and suzuki-miyaura cross-coupling as key steps
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Biaryl derivatives have been prepared by utilizing cross-enyne metathesis, Diels-Alder reaction followed by aromatization. These biaryl derivatives are further functionalized via Suzuki-Miyaura cross-coupling reaction to generate functionalized terphenyl derivatives. Georg Thieme Verlag Stuttgart - New York.
- Kotha, Sambasivarao,Seema, Vittal
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p. 2329 - 2334
(2011/10/30)
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- Synthesis of novel tetrachromophoric cascade-type Bodipy dyes
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Two series of multi-cascade scaffolds bearing a boradiazaindacene (yellow dye) or a boradibenzopyrromethene (green dye) as the final energy acceptor have been synthesized. Each scaffold contains one, two or three alkynylaryl energy donors (such as pyrene D1, perylene D2, and fluorene D3) linked to the boron center. Palladium-catalyzed cross-coupling of dihalogenated Bodipy starting material enabled the step-by-step construction of the different modules. In all cases, selective irradiation in each absorbing subunit resulted in efficient energy transfer over 25 ? to the Bodipy units.
- Goeb, Sébastien,Ziessel, Raymond
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p. 2569 - 2574
(2008/09/21)
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- HEPATITIS C VIRUS INHIBITORS
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The present disclosure relates to compounds of the following formula (I) or a pharmaceutically acceptable salt thereof, wherein A and B are each phenyl; D and E are each five-membered aromatic rings containing one, two, or three i hcteroatoms independently selected from nitrogen, oxygen, and sulfur; provided that ', at least one of D and E is other than imidazole; compositions and methods for the treatment of Hepatitis C virus (HCV) inf ection. Also disclosed are pharmaceutical compositions containing such compounds and methods f or using these compounds in the treatment of HCV inf ection.
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Page/Page column 27-28
(2009/01/20)
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- Convenient synthesis of green diisoindolodithienylpyrromethene-dialkynyl borane dyes
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(Graph Presented) Versatile dyes based on diisoindolodithienylpyrromethene substituted at the boron center by alkynylaryl chromophores have been developed that efficiently fluorescence in the near infrared. Fast intramolecular energy transfer from the appended alkynyl units to the central core provides Stokes shifts above 16 000 cm-1.
- Goeb, Sebastien,Ziessel, Raymond
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p. 737 - 740
(2007/10/03)
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- 4-Aryl-1,2,3-triazole: A novel template for a reversible methionine aminopeptidase 2 inhibitor, optimized to inhibit angiogenesis in vivo
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Inhibitors of human methionine aminopeptidase type 2 (hMetAP2) are of interest as potential treatments for cancer. A new class of small molecule reversible inhibitors of hMetAP2 was discovered and optimized, the 4-aryl-1,2,3-triazoles. Compound 24, a potent inhibitor of cobalt-activated hMetAP2, also inhibits human and mouse endothelial cell growth. Using a mouse matrigel model, this reversible hMetAP2 inhibitor was also shown to inhibit angiogenesis in vivo.
- Kallander, Lara S.,Lu, Qing,Chen, Wenfang,Tomaszek, Thaddeus,Yang, Guang,Tew, David,Meek, Thomas D.,Hofmann, Glenn A.,Schulz-Pritchard, Christina K.,Smith, Ward W.,Janson, Cheryl A.,Ryan, M. Dominic,Zhang, Gui-Feng,Johanson, Kyung O.,Kirkpatrick, Robert B.,Ho, Thau F.,Fisher, Paul W.,Mattern, Michael R.,Johnson, Randall K.,Hansbury, Michael J.,Winkler, James D.,Ward, Keith W.,Veber, Daniel F.,Thompson, Scott K.
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p. 5644 - 5647
(2007/10/03)
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- Efficient synthesis of a complete donor/acceptor bis(aryl)diyne family
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A facile route to a family of bis(aryl)diynes containing both an electron donating pyridine ring and an electron accepting iodobenzene has been developed. The convergent synthesis involves the coupling of 2-, 3-, or 4-bromopyridine with TMS-acetylene, followed by deprotection to form the first half of the molecule. Similarly, 2-, 3-, or 4-iodoaniline was coupled to TMS-acetylene after protection of the amine group as a diethyltriazine. After conversion of the triazine to an iodine, deprotection of the acetylene and formation of the corresponding bromophenyl-acetylene, the two halves of the molecule were coupled under Cadiot-Chodkiewicz conditions. Nine new compounds were prepared, each of which was found to thermally polymerize from the melt. None of the compounds underwent photochemical polymerization in the solid-state.
- Holmes, Brian T.,Pennington, William T.,Hanks, Timothy W.
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p. 2447 - 2461
(2007/10/03)
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- Selective and efficient access to ortho, meta and para ring-substituted phenylacetylene derivatives R-[C≡C-C6H4](x)-Y (Y:H, NO2, CN, I, NH2)
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ortho, meta and para isomers of iodo and amino ring-substituted phenylacetylene as well as rod-like arylacetylene derivatives were prepared by a simple synthetic route involving three consecutive reactions: the palladium-catalysed carbon-carbon bond forma
- Lavastre, Olivier,Cabioch, Sandrine,Dixneuf, Pierre H.,Vohlidal, Jiri
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p. 7595 - 7604
(2007/10/03)
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