- Gelation or crystallization? Subtle balance of structural factors for assembly of DBA derivatives with methyl esters
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Morphology of molecular aggregates is crucially affected by molecular shape and intermolecular interactions. In 2009, we reported the unusual gelation behaviour of a curved-butadiynyl-bridged cyclic pi-conjugated molecule, octadehydrodibenzo[12]annulene ([12]DBA), possessing two methyl ester groups in noncentrosymmetric positions. Aggregation of the [12]DBA derivative occurred anisotropically to give crystalline nanofibers, which finally formed an organogel. To investigate the aggregation behaviour of the related analogues, we synthesized octadehydrotribenzo[14]annulene ([14]DBA) derivatives with two and four methyl ester groups and revealed that the [14]DBAs gave not gels but crystals, in which the molecules are stacked not in a unidirectional manner but in an alternating way. The results indicate that the gelation and crystallization of the present molecular system is derived from the subtle balance of molecular shape and intermolecular interactions.
- Hisaki, Ichiro,Kometani, Eriko,Tohnai, Norimitsu,Miyata, Mikiji
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Read Online
- Photoswitchable enediynes: Use of cyclopropenone as photocleavable masking group for the enediyne triple bond
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Cyclopropenone 1, 2,3-benzobicyclo[8.1.0]undec-1(10)-en-4-yn-11-one, is a thermally stable compound showing no signs of decomposition after heating at 84 °C for 7 d, UV irradiation of which results in an efficient (Φ300 = 0.45) and quantitative
- Poloukhtine, Andrei,Popik, Vladimir V.
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Read Online
- Comparison of "Polynaphthalenes" Prepared by Two Mechanistically Distinct Routes
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The Bergman cyclization has long been known to produce polymers as side products. More recently, this attribute has been harnessed for the production of conjugated materials. However, the structures of these polymers have not been established. To resolve
- Johnson, James P.,Bringley, Dustin A.,Wilson, Erin E.,Lewis, Kevin D.,Beck, Larry W.,Matzger, Adam J.
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Read Online
- Self-assembly of radially π-extended tetrathiafulvalene tetramers for visible and near infrared electrochromic nanofiber
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The self-assembly and electrochromic nanofiber formation of radially 7pi;-extended tetrathiafulvalene (TTF) tetramers anchored to 1,2,4,5-tetraethynylbenzene were investigated. The tetramer with SBu-substituents underwent self-assembly in solution. Cationic species of the tetramer, obtained by chemical oxidation with Fe(ClO4)3, exhibited a marked electrochromism in the solution. Their electronic spectra revealed absorption bands corresponding to intermolecular mixed-valence aggregation based on (TTF//TTF)+, and π-aggregation based on (TTF?+//TTF?+) due to the strong molecular association in the cationic species. Furthermore, the tetramer formed an entangled nanoscale fibrous material from CHCl3 hexane. Electrochemical oxidation of the nanofiber on an indium tin oxide electrode revealed a repeatable redox profile. The nanofiber displayed remarkable electrochromic behavior: The color of the fiber changed from purple (neutral) to brown/brownish green (dication and trication) and green (tetracation). These color changes of the nanofiber are similar to those in solution, and the electronic spectra of the oxidized nanofibers reflected the stacked TTF units in the cationic nanofibers.
- Hasegawa, Masashi,Iyoda, Masahiko
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Read Online
- Benzocyclobutabiphenylene, the First Member of a Novel Series of Linear Cyclobutadienoid Acenes
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Palladium mediated ethynylation of iodoarenes coupled with cobalt catalysed alkyne cotrimerisations allows rapid access to benzocyclobutabiphenylene, a linear biphenylenoid, and two of its trimethylsilyl derivatives.
- Berris, Bruce C.,Hovakeemian, George H.,Vollhardt, K. Peter C.
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Read Online
- Partitioning MOF-5 into Confined and Hydrophobic Compartments for Carbon Capture under Humid Conditions
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Metal-organic frameworks (MOFs), by virtue of their remarkable uptake capability, selectivity, and ease of regeneration, hold great promise for carbon capture from fossil fuel combustion. However, their stability toward moisture together with the competit
- Ding, Nan,Li, Haiwei,Feng, Xiao,Wang, Qianyou,Wang, Shan,Ma, Li,Zhou, Junwen,Wang, Bo
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Read Online
- Acetylene-substituted phosphane oxides: Building blocks for macrocycles
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Phosphorus-based macrocycles with acetylenic scaffolds have been built from acetylene-substituted phosphane oxides that were formed from diisopropylphosphoramidic dibromide (3) and an acetylenic Grignard reagent. The four-and six-edged macrocycles 15 and
- Van Assema, Sander G. A.,De Jong, G. Bas,Ehlers, Andreas W.,De Kanter, Frans J. J.,Schakel, Marius,Spek, Anthony L.,Lutz, Martin,Lammertsma, Koop
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Read Online
- A new halogen bonding 1,2-iodo-triazolium-triazole benzene motif for anion recognition
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The synthesis of a series of halogen bonding (XB) acyclic anion receptors based on a novel 1,2-iodo-triazolium-triazole benzene motif is reported. A combination of one- and two-dimensional 1H and 19F NMR spectroscopic techniques eluc
- Beer, Paul D.,Bunchuay, Thanthapatra,Docker, Andrew,White, Nicholas G.
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- Are bis(pyridine)iodine(i) complexes applicable for asymmetric halogenation?
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Enantiopure halogenated molecules are of tremendous importance as synthetic intermediates in the construction of pharmaceuticals, fragrances, flavours, natural products, pesticides, and functional materials. Enantioselective halofunctionalizations remain
- Andreasson, M?ns,Erdelyi, Mate,Németh, Flóra Boróka,Pápai, Imre,Sethio, Daniel,von der Heiden, Daniel
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p. 8307 - 8323
(2021/10/12)
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- Gold-Catalyzed Carbazolation Reactions of Alkynes
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Herein, we report on a Au(I)-catalyzed reaction of alkynes with carbazoles that enables a one-step synthesis of vinyl carbazoles that are important molecules for applications as photoluminescent materials. This reaction proceeds under mild conditions at r
- He, Feifei,Jana, Sripati,Koenigs, Rene M.
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supporting information
(2020/07/03)
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- Chiral double stapled: O -OPEs with intense circularly polarized luminescence
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Intrinsically chiral double stapled ortho-oligo phenylene ethynylenes (o-OPEs) 1 show glum values up to 5.5 × 10-2, the second highest value ever observed for a simple organic molecule (SOM). DFT calculations of molecular spectra and
- Reine, Pablo,Campa?a, Araceli G.,Alvarez De Cienfuegos, Luis,Blanco, Victor,Abbate, Sergio,Mota, Antonio J.,Longhi, Giovanna,Miguel, Delia,Cuerva, Juan M.
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supporting information
p. 10685 - 10688
(2019/09/13)
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- Sulfoxide-Induced Homochiral Folding of ortho-Phenylene Ethynylenes (o-OPEs) by Silver(I) Templating: Structure and Chiroptical Properties
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A new family of homochiral silver complexes based on carbophilic interactions with ortho-phenylene ethynylene (o-OPE) scaffolds containing up to two silver atoms are described. These compounds represent a unique class of complexes with chirality at the me
- Resa, Sandra,Miguel, Delia,Guisán-Ceinos, Santiago,Mazzeo, Giuseppe,Choquesillo-Lazarte, Duane,Abbate, Sergio,Crovetto, Luis,Cárdenas, Diego J.,Carre?o, M. Carmen,Ribagorda, María,Longhi, Giovanna,Mota, Antonio J.,álvarez de Cienfuegos, Luis,Cuerva, Juan M.
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p. 2653 - 2662
(2018/02/06)
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- Glucose selective bis-boronic acid click-fluor
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Four novel bis-boronic acid compounds were synthesised via copper catalysed azide-alkyne cycloaddition (CuAAC) reactions. Glucose selectivity was observed for a particular structural motif. Moreover, a new glucose selective fluorescent sensor was designed
- Zhai, Wenlei,Male, Louise,Fossey, John S.
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supporting information
p. 2218 - 2221
(2017/02/23)
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- How Boron Doping Shapes the Optoelectronic Properties of Canonical and Phenylene-Containing Oligoacenes: A Combined Experimental and Theoretical Investigation
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Optimized syntheses of 6,13-dimesityl-6,13-dihydro-6,13-diborapentacene (DBP) and a related compound (DBI) featuring two biphenylene-2,3-diyl units in place of naphthalene-2,3-diyl moieties are reported. Striking differences between the optoelectronic properties of DBP and DBI have been experimentally observed, and explained by quantum chemical calculations. DBP is a member of the oligoacene family, DBI is a linear [N]phenylene derivative. The yellow DBP shows blue photoluminescence, the deep red DBI is nonfluorescent. Both compounds give rise to two reversible redox transitions at E12 =?2.03 V, ?2.75 V (DBP) and ?1.52 V, ?2.30 V (DBI; THF, vs. FcH/FcH+). The higher electron affinity of DBI agrees with a lower calculated LUMO energy level [?0.57 eV for DBI with respect to DBP @HF//SCS-MP2/def2-TZVP] and a higher Lewis acidity of its boron centers, which is reflected in the trend of adduct formation with small Lewis bases (MeCN, F?). The thermochemistry underlying this trend, as well as the mechanism of fluorescence quenching in DBI, are revealed by state-of-the-art quantum chemical calculations. It is suggested that the nonradiative deactivation occurs via a low-lying, doubly excited state.
- Kirschner, Sven,Mewes, Jan-Michael,Bolte, Michael,Lerner, Hans-Wolfram,Dreuw, Andreas,Wagner, Matthias
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supporting information
p. 5104 - 5116
(2017/04/18)
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- Functional organic click-materials: application in phosphorescent organic light emitting diodes
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In the presented work click chemistry is utilized to introduce 1,2,3-triazoles as a functional linker in organic donor-acceptor materials. A systematic series of materials was prepared and characterized to investigate the effect of the linkage mode on the molecular properties. The 1,2,3-triazole linker allowed control of the degree of intramolecular charge transfer over a wide range depending on the substitution pattern of the triazole moiety. The prepared materials were successfully employed as host materials for green and red dopants in phosphorescent organic light emitting diodes. Thus, this work presents the first application of this novel linkage mode in the design and synthesis of functional π-conjugated organic donor-acceptor materials and their application in organic light emitting diodes.
- Kautny, Paul,Zhao, Chenyang,Kader, Thomas,St?ger, Berthold,Horkel, Ernst,Chen, Jiangshan,Ma, Dongge,Fr?hlich, Johannes,Lumpi, Daniel
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p. 12150 - 12160
(2017/03/08)
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- CO extrusion in homogeneous gold catalysis: Reactivity of gold acyl species generated through water addition to gold vinylidenes
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Herein, we describe a new gold-catalyzed decarbonylative indene synthesis. Synergistic σ,π-activation of diyne substrates leads to gold vinylidene intermediates, which upon addition of water are transformed into gold acyl species, a type of organogold compound hitherto only scarcely reported. The latter are shown to undergo extrusion of CO, an elementary step completely unknown for homogeneous gold catalysis. By tuning the electronic and steric properties of the starting diyne systems, this new reactivity could be exploited for the synthesis of indene derivatives in high yields.
- Bucher, Janina,St?sser, Tim,Rudolph, Matthias,Rominger, Frank,Hashmi, A. Stephen K.
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supporting information
p. 1666 - 1670
(2015/01/30)
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- Gold-catalyzed hydroarylating cyclization of 1,2-Bis(2-iodoethynyl)benzenes
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1,5-Diynes bearing halogen-substituted alkynes were synthesized and converted in the presence of a gold catalyst. In contrast to the corresponding hydroarylating aromatization reaction with terminal alkynes, a totally different reaction mode was observed.
- N?sel, Pascal,Müller, Vanessa,Mader, Steffen,Moghimi, Setareh,Rudolph, Matthias,Braun, Ingo,Rominger, Frank,Hashmi, A. Stephen K.
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supporting information
p. 500 - 506
(2015/03/05)
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- Luminescent coordination glass: Remarkable morphological strategy for assembled eu(iii) complexes
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Syntheses of novel luminescent Eu(III) coordination glasses 1 ([Eu(hfa)3(o-dpeb)]2), 2 ([Eu(hfa)3(m-dpeb)]3), and 3 ([Eu(hfa)3(p-dpeb)]n) are reported. They are composed of Eu(III) ions, he
- Hirai, Yuichi,Nakanishi, Takayuki,Kitagawa, Yuichi,Fushimi, Koji,Seki, Tomohiro,Ito, Hajime,Fueno, Hiroyuki,Tanaka, Kazuyoshi,Satoh, Toshifumi,Hasegawa, Yasuchika
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p. 4364 - 4370
(2015/05/20)
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- Synthesis and structure of conjugated molecules with the benzofulvene core
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A general method to synthesize conjugated molecules with a benzofulvene core is reported. Up to four conjugated substituents have been introduced via a three-step sequence including (1) synthesis of 1,2-bis(arylethynyl)benzenes; (2) exo-dig electrophilic cyclization promoted by iodine; and (3) cross-coupling reaction of the resulting bis-iodobenzofulvenes with organoboron, organotin, or ethynyl derivatives under Pd catalysis. Structural aspects of the new compounds are discussed.
- Martinelli, Carmela,Cardone, Antonio,Pinto, Vita,Mastropasqua Talamo, Maurizio,D'Arienzo, Maria Luisa,Mesto, Ernesto,Schingaro, Emanuela,Scordari, Fernando,Naso, Francesco,Musio, Roberta,Farinola, Gianluca M.
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p. 3424 - 3427
(2014/07/21)
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- A rhomboid-shaped organic host molecule with small binding space. Unsymmetrical and symmetrical inclusion of halonium ions
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A shape persistent rhomboid-shaped organic host molecule having two pyridyl units was synthesized which induces size selective halonium inclusion. Cl + and Br+ are included to form unsymmetric and symmetric complexes, while I+/
- Suzaki, Yuji,Saito, Takashi,Ide, Tomohito,Osakada, Kohtaro
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p. 6643 - 6649
(2014/05/06)
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- Oxidative cyclodimerization after tandem cyclization of dehydrobenzo[14]annulenes induced by alkyllithium
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After eight: Reactions of dehydrobenzo[14]annulenes induced by the addition of n-butyllithium led to the discovery of an unprecedented oxidative cyclodimerization, which forms eight-membered ring products in up to 30 % yield. The product contains two inde
- Nobusue, Shunpei,Shimizu, Akihiro,Hori, Kenji,Hisaki, Ichiro,Miyata, Mikiji,Tobe, Yoshito
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supporting information
p. 4184 - 4188
(2013/05/21)
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- Grignard reagent/CuI/LiCl-mediated stereoselective cascade addition/cyclization of diynes: A novel pathway for the construction of 1-methyleneindene derivatives
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Diynes containing a cyclopropane group smoothly undergo a novel intramolecular and stereoselective cascade addition/cyclization reaction to produce the corresponding 1-methyleneindene derivatives in moderate to good yields. This interesting transformation is mediated by Grignard reagent/CuI with LiCl as an additive under mild conditions. The obtained product can easily be further functionalized through cyclopropyl ring opening. A plausible reaction mechanism has also been presented on the basis of deuterium labeling and control experiments. Diyne cyclization: Diynes containing a cyclopropane group undergo a novel intramolecular and stereoselective cascade addition/cyclization reaction to produce the corresponding 1-methyleneindene derivatives (see scheme). The transformation proceeds under mild conditions and is promoted by a combination of Grignard reagent Copyright
- Li, De-Yao,Wei, Yin,Shi, Min
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supporting information
p. 15682 - 15688
(2013/11/19)
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- Polymorphism of dehydrobenzo[14]annulene possessing two methyl ester groups in noncentrosymmetric positions
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We revealed that the π-conjugated cyclic compound octadehydrotribenzo[14]annulene ([14]DBA), with two methyl ester groups in noncentrosymmetric positions, formed five polymorphic crystals: forms I (plate, P21/c), II (block, P21/c), II′ (block P1), III (needle, P21/c), and IV (needle, C2/c), which is the largest number for polymorphic crystals of the DBA family. Forms I, III, and IV can be obtained selectively upon the crystallization conditions applied. The present polymorphism was provided by conformational flexibility and varied CH/O interaction methods of the methyl ester groups. The thermal stability, fluorescence properties, and photoconductivity of the polymorphs were investigated. Such properties are affected by the polymorphic supramolecular structure. Furthermore, we demonstrate that the polymorphs exhibit physical or chemical defects depending on the magnitude of the π-overlap of the DBA planes and that the fluorescence and electronic properties are strongly affected by the defects. Particularly, form I shows a significant fluorescence band at 530 nm, probably due to defects in the crystals.
- Hisaki, Ichiro,Kometani, Eriko,Shigemitsu, Hajime,Saeki, Akinori,Seki, Shu,Tohnai, Norimitsu,Miyata, Mikiji
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experimental part
p. 5488 - 5497
(2012/04/04)
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- Ligand bridging-angle-driven assembly of molecular architectures based on quadruply bonded Mo-Mo dimers
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A systematic exploration of the assembly of Mo2(O 2C-)4-based metal-organic molecular architectures structurally controlled by the bridging angles of rigid organic linkers has been performed. Twelve bridging dicarboxylate ligands were designed to be of different sizes with bridging angles of 0, 60, 90, and 120° while incorporating a variety of nonbridging functional groups, and these ligands were used as linkers. These dicarboxylate linkers assemble with quadruply bonded Mo-Mo clusters acting as nodes to give 13 molecular architectures, termed metal-organic polygons/polyhedra with metal cluster node arrangements of a linear shape, triangle, octahedron, and cuboctahedron/anti-cuboctahedron. The syntheses of these complexes have been optimized and their structures determined by single-crystal X-ray diffraction. The results have shown that the shape and size of the resulting molecular architecture can be controlled by tuning the bridging angle and size of the linker, respectively. Functionalization of the linker can adjust the solubility of the ensuing molecular assembly but has little or no effect on the geometry of the product. Preliminary gas adsorption, spectroscopic, and electrochemical properties of selected members were also studied. The present work is trying to enrich metal-containing supramolecular chemistry through the inclusion of well-characterized quadruply bonded Mo-Mo units into the structures, which can widen the prospect of additional electronic functionality, thereby leading to novel properties.
- Li, Jian-Rong,Yakovenko, Andrey A.,Lu, Weigang,Timmons, Daren J.,Zhuang, Wenjuan,Yuan, Daqiang,Zhou, Hong-Cai
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supporting information; experimental part
p. 17599 - 17610
(2011/02/26)
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- Tetranuclear copper(I) iodide complexes of chelating bis(1 -benzyl-1 H-1,2,3triazole) ligands: Structural characterization and solid state photoluminescence
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A series of tetranuclear Cu4l4(Ln)2 clusters (1-3) supported by the chelating 4,4'-(4,5-diX-1,2-phenylene)bls(1 -benzyl-1 H-1,2,3-triazole) ligands (L1, X = H; L2, X = CH3; L3, X = F) have been prepared. Crystal
- Manbeck, Gerald F.,Brennessel, William W.,Evans, Christopher M.,Eisenberg, Richard
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experimental part
p. 2834 - 2843
(2010/05/15)
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- Synthesis, functionalization and photo-Bergman chemistry of enediyne bioconjugates
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Methodology is outlined for the chemical synthesis of versatile photo-Bergman enediyne building blocks and their conjugates. Routes to both mono and bis conjugated enediyne templates are detailed together with representative examples of their bioconjugate
- LaBeaume, Paul,Wager, Krista,Falcone, Danielle,Li, Jane,Torchilin, Vladimir,Castro, Curtis,Holewa, Coleen,Kallmerten, Amy E.,Jones, Graham B.
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supporting information; experimental part
p. 6292 - 6300
(2011/02/26)
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- Synthetic and mechanistic investigations on the rearrangement of 2,3-unsaturated 1,4-bis(alkylidene)carbenes to enediynes
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The synthesis of 3,4-ene-1,5-diynes, the key structural moiety present in several naturally occurring antitumor antibiotics, from 1,2-enedialdehydes under two different experimental conditions is reported. One method involves the dibromomethylenation of dialdehydes under Corey-Fuchs conditions (CBr 4, Ph3P, and Zn) and treatment of the resulting tetrabromides with nBuLi or LDA to afford enediynes. The second method involves a base-mediated reaction of enedialdehydes with diethyl (1-diazo-2-oxopropyl) phosphonate (Bestmann-Ohira reagent) and subsequent transformation of the bis(diazo) compounds generated in situ to enediynes. While the transformation of bis(diazo) compounds to enediynes could take place exclusively through alkylidene-carbenes, generated in situ by geminal elimination of N2, an alternative pathway, involving the vicinal elimination of HBr to afford an intermediate bromoalkyne and its subsequent metal-halogen exchange and protonation during workup, exists for the bis(dibromoalkylidenes). However, our deuterium-labeling experiments with a model substrate, deuterated p-methoxybenzylidene dibromide, established the predominance of the alkylidenecarbenes, generated in situ by metal-halogen exchange and elimination, for this substrate and, by analogy, for the tetrabromides as well. The scope of this novel methodology was extended to the synthesis of various heteroatom-based (S, Se, and P) enediynes by quenching the acetylides with suitable electrophiles. Wiley-VCH Verlag GmbH & Co. KGaA, 2007.
- Sahu, Bichismita,Muruganantham, Rajendran,Namboothiri, Irishi N. N.
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p. 2477 - 2489
(2008/03/13)
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- Phosphepines: Convenient access to phosphinidene complexes
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Reaction of o-diethynylbenzene with transition metal-complexed primary phosphines gives in a single base-induced step stable phosphepine complexes as confirmed by X-ray data. At 75-80 °C these phosphepines undergo clean cheletropic elimination of naphthalene to give transient carbene-like phosphinidene complexes that can be trapped in high yield by alkenes, alkynes, and alcohols. Copyright
- Borst, Mark L. G.,Bulo, Rosa E.,Winkel, Christiaan W.,Gibney, Daniele J.,Ehlers, Andreas W.,Schakel, Marius,Lutz, Martin,Spek, Anthony L.,Lammertsma, Koop
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p. 5800 - 5801
(2007/10/03)
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- Cytotoxicities, cell cycle and caspase evaluations of 1,6-diaryl-3(Z)- hexen-1,5-diynes, 2-(6-aryl-3(Z)-hexen-1,5-diynyl)anilines and their derivatives
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Compounds 3, 6-7, 9-10, 15-17, and 20-21 showed growth inhibition effects on a full panel of 60 human cancer cell lines, and most of the average IC 50 values of the indicated analogues were from 0.01 to 96.6 μM, in which analogues 16 and 17 re
- Lin, Chi-Fong,Lo, Yu-Hsiang,Hsieh, Ming-Chu,Chen, Yi-Hua,Wang, Jeh-Jeng,Wu, Ming-Jung
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p. 3565 - 3575
(2007/10/03)
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- Construction of triangular metallomacrocycles: [M3(1,2-bis(2, 2′:6′,2″-terpyridin-4-yl-ethynyl)benzene)3] [M = Ru(II), Fe(II), 2Ru(II)Fe(II)]
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Complexation of a predesigned (1,2-bis(2,2′:6′,2″- terpyridin-4-yl-ethynyl)benzene) ligand possessing a 60° angle between two terpyridines with transition metals [Fe(II) and Ru(II)] afforded the self-assembled, triangular metallomacrocycles. The Royal Soc
- Hwang, Seok-Ho,Moorefield, Charles N.,Fronczek, Frank R.,Lukoyanova, Olena,Echegoyen, Luis,Newkome, George R.
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p. 713 - 715
(2007/10/03)
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- 3H-benzophosphepine complexes: Versatile phosphinidene precursors
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The synthesis of a variety of benzophosphepine complexes [R = Ph, t-Bu, Me; MLn = W(CO)5, Mo(CO)5, Cr(CO)5, Mn(CO)2Cp] by two successive hydrophosphinations of 1,2-diethynylbenzene is discussed in det
- Borst, Mark L. G.,Bulo, Rosa E.,Gibney, Daniele J.,Alem, Yonathan,De Kanter, Frans J. J.,Ehlers, Andreas W.,Schakel, Marius,Lutz, Martin,Spek, Anthony L.,Lammertsma, Koop
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p. 16985 - 16999
(2007/10/03)
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- Synthesis of arenediynes via the vinylidenecarbene-acetylene rearrangement
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A convenient method for the two-step synthesis of arenediynes from 1,2-arenedialdehydes is reported. Dibromomethylenation of dialdehydes under Corey-Fuchs conditions (CBr4, Ph3P, Zn) provides the tetrabromides in excellent yields. Treatment of the tetrabromides with n-BuLi or LDA affords 3,4-unsaturated 1,5-diynes, the key structural moiety present in several naturally occurring antitumour antibiotics, in varying yields. The key intermediates in these transformations appear to be vinylidenecarbenes or carbenoids, generated in situ via metal-halogen exchange and elimination.
- Sahu, Bichismita,Namboothiri, Irishi N.N.,Persky, Rachel
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p. 2593 - 2597
(2007/10/03)
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- Simplified synthesis of 1,1′[14C]-methylene-di (2-naphthol). A radiochemical and kinetic approach
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The synthesis of the 1,1′[14C]-methylene-di-(2-naphthol) 2, as the radiolabeled probe of a possible interaction between the β-amyloid fibrils and the di-naphthol mojety in the Alzheimer's disease, is reported. Very simple radiochemical procedure, starting from [ 14C]paraformaldehyde, produced 8.66 MBq of compound 2 at the specific radioactivity of 1.22 TBq/mol. A mechanistic and kinetic approach allowed the comprehension of the right experimental conditions. The stability of compound 2 in acetonitrile solution was investigated, denoting a significative decomposition process through the transient formation of the 1,2-naphthyne intermediate. Copyright
- Angelini, Giancarlo,Ursini, Ornella,Minetti, Patrizia,Celona, Diana,De Angelis, Francesco
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p. 543 - 556
(2007/10/03)
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- Diatropicity of 3,4,7,8,9,10,13,14-octadehydro[14]annulenes: A combined experimental and theoretical investigation
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The synthesis and study of a series of octadehydro[14]annulenes is described. The aromaticity of these annulenes was investigated through examination of experimental data from arene-fused systems as well as calculated nucleus-independent chemical shifts (NICS) and bond lengths. Benzene ring fusion to the parent system results in a stepwise loss in aromaticity as the number of fused rings is increased from one to two to three. This decrease in annulenic ring current is manifested in the alkene proton chemical shifts (0-2 benzenes) as well as the NICS (0-3 benzenes). Comparison of isomeric thiophene-fused annulenes shows further evidence of ring current competition as these allow for observation of intermittent degrees of delocalization throughout the annulenic core. A consistent relationship between the magnitude of the NICS values and the degree of benzannelation is also observed.
- Boydston, Andrew J.,Haley, Michael M.,Williams, Richard Vaughan,Armantrout, John R.
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p. 8812 - 8819
(2007/10/03)
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- Carbonyl- and carboxyl-substituted enediynes: Synthesis, computations, and thermal reactivity
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The influence of electron-withdrawing groups (carbonyl and carboxyl) at the alkyne termini on the reactivity of enediynes was investigated by a combination of experimental and computational techniques. While the general chemical reactivity of such enediynes, especially if non-benzannelated, is increased markedly, the thermal cyclization, giving rise to Bergman cyclization products, is changed little relative to the parent enediyne system. This is evident from kinetic measurements and from density functional theory (DFT, BLYP/6-31G* + thermal corrections) computations of the experimental systems which show that the Bergman cyclization barriers slightly (3-4 kcal/mol) increase, in contrast to earlier theoretical predictions. The effect on the endothermicities is large (ΔΔHr = 7-12 kcal/mol). Hence, the increased reactivity of the substituted enediynes is entirely due to nucleophiles or radicals present in solution. This was demonstrated by quantitative experiments with diethylamine and tetramethyl piperidyl oxide (TEMPO) which both give fulvenes through 5-exo-dig cyclizations.
- Koenig,Pitsch,Klein,Vasold,Prall,Schreiner
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p. 1742 - 1746
(2007/10/03)
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- On the nature of nonplanarity in the [N]phenylenes
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The [N]phenylenes display marked deformation from planarity in the crystalline state. In order to probe the generality of this phenomenon, several derivatives were synthesized and their single-crystal X-ray structures were obtained. All new compounds disp
- Holmes, Daniel,Kumaraswamy, Sriram,Matzger, Adam J.,Vollhardt, K. Peter C.
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p. 3399 - 3412
(2007/10/03)
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- Synthesis of terminal-biradical compounds consisting of two N-oxyl groups connected with conjugated π-systems
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Terminal-biradical compounds 1 having two N-oxyl groups connected with conjugated π-systems were synthesized by (1) addition of magnesium acetylide to 4-oxo-TEMPO, followed by dehydration, or (2) cross-coupling between acetylene and vinyl triflate derived from 4-oxo-TEMPO.
- Torii, Sigeru,Hase, Tomoyuki,Kuroboshi, Manabu,Amatore, Christian,Jutand, Anny,Kawafuchi, Hiroyuki
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p. 7391 - 7394
(2007/10/03)
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- Synthesis of polyphenylene derivatives by thermolysis of enediynes and dialkynylaromatic monomers
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Described are the syntheses of substituted enediynes and dialkynylaromatics using Pd- or Pd/Cu-catalyzed cross coupling procedures. The products were then thermalized to afford the corresponding poly(p- phenylene)s, poly(1,4-naphthalene)s, poly(benzo[c]thiophene)s, and poly(dibenzothiophene)s. Fifteen examples are provided that show the scope of the polymerization process based upon substituent patterns and cyclization moieties. The superb thermal resiliency of the newly derived polymers is demonstrated using thermogravimetric analysis. The polymer structure was generally confirmed using IR data correlations to small molecules that resembled the polymers' repeat unit structure. Radical trapping of dimeric intermediates, that were analyzed by GCMS, further substantiated the proposed mechanistic route. The step-growth polymerization pattern was determined by monitoring the degree of monomer consumption versus the polymer molecular weight.
- John, Jens A.,Tour, James M.
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p. 15515 - 15534
(2007/10/03)
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- Convenient preparation of di- and tri-ethynylbenzenes by cleavage of 2-hydroxy-2-methylbut-3-yn-4-yl-benzenes with water miscible reagents
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2-Hydroxy-2-methylbut-3-yn-4-yl-benzenes, readily available from bromobenzenes, are efficiently cleaved by the water-miscible reagents sodium 2-propoxide in 2-propanol, or potassium hydroxide in dioxan, which facilitatese isolation of volatile ethynylbenzenes.
- MacBride, J.A. Hugh,Wade, Kenneth
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p. 2309 - 2316
(2007/10/03)
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- Intramolecular Reaction Of Nitroxide Radicals With Biradical Intermediates Generated From Aromatic Enediynes
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1,4-Dehydronaphthalene biradicals generated by thermolysis of aromatic enediynes can be trapped with the nitroxide radical TEMPO.The isolated products, however, are not the direct trapping products but 1,4-naphthoquinones resulting from the homolysis of N-O bonds of trapping products.
- Grissom, Janet Wisniewski,Gunawardena, Gamini U.
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p. 4951 - 4954
(2007/10/02)
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- Synthesis of Diacetylene Macrocycles Derived from 1,2-Diethynylbenzene Derivatives: Structure and Reactivity of the Strained Cyclic Dimer
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Diacetylene macrocycles 2-4 (n=1-3) (R=H, C4H9, C6H13, C10H21, C12H25, OC10H21) have been prepared from the oxidative coupling of 1,2-diethynylbenzene derivatives.These compounds can be produced in useful quantities and are of interest as precursors to novel conjugated organic polymers.The reported results indicate that when the R groups are large the dimeric macrocycle (n=1) can be prepared in as high as 74percent yield from the corresponding 1,2-diethynylbenzene in a one-step procedure.An alternate multistep procedure was found to produce the tetrameric macrocycle (n=3,R=C6H13) in 45percent yield.The highly strained dimeric macrocycle was characterized by an X-ray structure and was found to be very reactive.The dimers undergo a rapid very exothermic polymerization at 100-125 deg C, indicative of a chain reaction.Reaction of the dimeric macrocycles with iodine results in intramolecular cyclization and a new 20? electron tetraiodide fused ring system.Reaction of the tetraiodide with oxygen produces a related compound in which two of the iodides have been converted to ketones.
- Zhou, Qin,Carroll, Patrick J.,Swager, Timothy M.
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p. 1294 - 1301
(2007/10/02)
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- Arene 1,4-diradical formation from o-dialkynylarenes
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A series of five arene and quinone derivatives with dialkynyl substituents in the ortho positions and fixed in a 10-membered ring were prepared and tested with respect to thermal rearrangement to the corresponding arene 1,4 diradicals.
- Semmelhack,Neu, Thomas,Foubelo, Francisco
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p. 3277 - 3280
(2007/10/02)
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- Synthesis of diethynylbenzene
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The invention provides an inexpensive synthesis process for preparation of diethynylbenzene monomers that are useful in the preparation of polyacetylenes. This process provides for the preparation of thermally sensitive monomers in a one-pot reaction usin
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- A SHORT ROUTE TO DEHYDRO ANNULENES
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A novel synthesis of dehydro annulenes from 1,2-dibromobenzene is based on selective Pd(0)-Cu(1) coupling reactions of aryl and vinyl halides with terminal acetylenes.
- Huynh, Chanh,Linstrumelle, Gerard
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p. 6337 - 6344
(2007/10/02)
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- 5,12-dihydro-6,11-didehydronaphthacene, A derivative of 1,4-didehydronaphthalene
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Treatment of the di-lithium derivative of 1,2-diethynyl-benzene (1) with o-xylene-α,α′-diol di-p-toluenesulphonate (2) in tetrahydrofuran led to 5,12-dihydronapthacene (5) as the only identifiable product. This reaction presumably involves 5,12-dihydro-6,11-didehydronaphthacene (4) as an intermediate, and this was confirmed by the formation of 5,12-dihydro-6,11-dideuterio-naphthacene when the reaction was carried out in tetrahydrofuran-d8.
- Wong, Henry N.C.,Sondheimer, Franz
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p. 217 - 220
(2007/10/02)
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