- Preparation and Structure of Dichloropalladium(II) Complexes of Sterically Protected Diphosphinidenecyclobutanes and Their Synthetic Application as Homogeneous Catalyst.
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Sterically protected 3,4-biscyclobutenes reacted with bis(acetonitrile)-dichloropalladium(II) to give the corresponding dichloropalladium complexes and the structure of one of the complexes was confirmed by X-ray cr
- Toyota, Kozo,Masaki, Kazuto,Abe, Tetsuya,Yoshifuji, Masaaki
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- Effect of the π-bridge on the light absorption and emission in push-pull coumarins and on their supramolecular organization
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A family of eight π-extended push–pull coumarins with cross-conjugated (amide) and directly conjugated (p-phenylene, alkyne, alkene) bridges were synthesized through a convergent strategy. Using an experimentally calibrated computational protocol, their UV–Visible light absorption and emission spectra in solution were investigated. Remarkably, amide-, alkyne- and alkene-bridges undergo comparable vertical excitations. The different nature of these bridges manifests during excited-state relaxation and fluorescence. We predict that these molecules can serve as building blocks for p-type semiconductors with low reorganization energies, below 0.2 eV. Since solid-state self-assembly is crucial for this application, we examined the effect of the π-bridge over the supramolecular organization in this family of compounds to determine if stacking prevails in these π-extended coumarin derivatives. Amide and alkyne spacers allow coplanar conformations which crystallize readily; p-phenylene hinders planarity yet allows facile crystallization; alkene-bridged molecules eluded all crystallization attempts. All the crystals obtained feature dense face-to-face π-stacking with 3.5–3.7 ? interlayer distances, expected to facilitate charge transfer processes in the solid state.
- Arcos-Ramos, Rafael,Carreón-Castro, María del Pilar,Farfán, Norberto,González-Rodríguez, Edgar,Guzmán-Juárez, Brenda,Maldonado-Domínguez, Mauricio,Miranda-Olvera, Montserrat,Santillan, Rosa
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supporting information
(2021/11/08)
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- Gold N-Heterocyclic Carbene Catalysts for the Hydrofluorination of Alkynes Using Hydrofluoric Acid: Reaction Scope, Mechanistic Studies and the Tracking of Elusive Intermediates
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An efficient and chemoselective methodology deploying gold-N-heterocyclic carbene (NHC) complexes as catalysts in the hydrofluorination of terminal alkynes using aqueous HF has been developed. Mechanistic studies shed light on an in situ generated catalyst, formed by the reaction of Br?nsted basic gold pre-catalysts with HF in water, which exhibits the highest reactivity and chemoselectivity. The catalytic system has a wide alkyl substituted-substrate scope, and stoichiometric as well as catalytic reactions with tailor-designed gold pre-catalysts enable the identification of various gold species involved along the catalytic cycle. Computational studies aid in understanding the chemoselectivity observed through examination of key mechanistic steps for phosphine- and NHC-coordinated gold species bearing the triflate counterion and the elusive key complex bearing a bifluoride counterion.
- Bédard, Sandrine,Cavallo, Luigi,Falivene, Laura,Gauthier, Rapha?l,Nolan, Steven P.,Paquin, Jean-Fran?ois,Saab, Marina,Tzouras, Nikolaos V.,Van Hecke, Kristof,Zhang, Ziyun
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- Chemoselective Cleavage of Si-C(sp3) Bonds in Unactivated Tetraalkylsilanes Using Iodine Tris(trifluoroacetate)
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Organosilanes are synthetically useful reagents and precursors in organic chemistry. However, the typical inertness of unactivated Si-C(sp3) bonds under conventional reaction conditions has hampered the application of simple tetraalkylsilanes in organic synthesis. Herein we report the chemoselective cleavage of Si-C(sp3) bonds of unactivated tetraalkylsilanes using iodine tris(trifluoroacetate). The reaction proceeds smoothly under mild conditions (-50 °C to room temperature) and tolerates various polar functional groups, thus enabling subsequent Tamao-Fleming oxidation to provide the corresponding alcohols. NMR experiments and density functional theory calculations on the reaction indicate that the transfer of alkyl groups from Si to the I(III) center and the formation of the Si-O bond proceed concertedly to afford an alkyl-λ3-iodane and silyl trifluoroacetate. The developed method enables the use of unactivated tetraalkylsilanes as highly stable synthetic precursors.
- Matsuoka, Keitaro,Komami, Narumi,Kojima, Masahiro,Mita, Tsuyoshi,Suzuki, Kimichi,Maeda, Satoshi,Yoshino, Tatsuhiko,Matsunaga, Shigeki
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supporting information
p. 103 - 108
(2021/01/13)
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- Metal scavenging and catalysis by periodic mesoporous organosilicas with 2,2′-bipyridine metal chelating ligands
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A periodic mesoporous organosilica containing 2,2′-bipyridine (BPy-PMO) was assessed as a metal scavenger and heterogeneous catalyst. The functionalized PMO was synthesized based on a modified version of a previously reported procedure and showed a large
- Waki, Minoru,Inagaki, Shinji
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- Molybdenum Benzylidyne Complexes for Olefin Metathesis Reactions
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The molybdenum benzylidynes [ArCMo(OC(CF3)2CH3)3(1,2-dimethoxyethane)], where Ar = Ph (2a), p-(OCH3)C6H4 (2b), p-(CF3)C6H4 (2c), p-(NO2)C6H4 (2d), or 4-(NO2)-3-(CF3)C6H3 (2e), and [p-(NO2)C6H4CMo(OC(CF3)2CH3)3] (2f) catalyze the ring-closing metathesis (RCM) reaction of diallyl N-tosylamide (3) to produce 1-tosyl-2,5-dihydro-1H-pyrrole (4) and ethylene. The scope of RCM catalytic activity of 2e, cross-metathesis of 1-hexene, and ring-opening metathesis polymerization of cyclooctene were explored. The X-ray crystal structure of 2e was determined. Variable-temperature 1H NMR spectra revealed the formation of intermediates during the reaction of 3 with 2f and the reforming of 2f after completion of the reaction. The use of 13C-labeled Mo benzylidyne did not show transfer of the carbon atom next to Mo to any of the products.
- Acosta, Carlos M.,Bukhryakov, Konstantin V.,Chuprun, Sergey,Mathivathanan, Logesh
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supporting information
p. 3453 - 3457
(2020/11/02)
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- Catalytic Decarboxylation of Silyl Alkynoates to Alkynylsilanes
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Herein, we describe a decarboxylative approach to the preparation of alkynylsilanes. Treatment of a silyl alkynoate in N,N-dimethylformamide (DMF) at 80 °C in the presence of catalytic amounts of CuCl and PCy3 produced the corresponding alkynylsilane in excellent yield. The copper-catalyzed decarboxylation proceeded smoothly with low catalyst loadings (0.5 mol % of CuCl and 1.0 mol % of PCy3) under mild reaction conditions and is easily scalable to gram quantities.
- Aoyagi, Keiya,Choi, Jun-Chul,Kawatsu, Takahiro,Matsumoto, Kazuhiro,Nakajima, Yumiko,Sato, Kazuhiko
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supporting information
(2020/09/15)
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- Rational Design, synthesis and biological evaluation of novel triazole derivatives as potent and selective PRMT5 inhibitors with antitumor activity
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Protein arginine methyltransferase 5 (PRMT5) is responsible for the mono-methylation and symmetric dimethylation of arginine, and its expression level and methyl transferring activity have been demonstrated to have a close relationship with tumorigenesis, development and poor clinical outcomes of human cancers. Two PRMT5 small molecule inhibitors (GSK3326595 and JNJ-64619178) have been put forward into clinical trials. Here, we describe the design, synthesis and biological evaluation of a series of novel, potent and selective PRMT5 inhibitors with antiproliferative activity against Z-138 mantle cell lymphoma cell line. Among them, compound C_4 exhibited the highest potency with enzymatic and cellular level IC50 values of 0.72 and 2.6 μM, respectively, and displayed more than 270-fold selectivity toward PRMT5 over several other isoenzymes (PRMT1, PRMT4 and PRMT6). Besides, C_4 demonstrated obvious cell apoptotic effect while reduced the cellular symmetric arginine dimethylation levels of SmD3 protein. The potency, small size, and synthetic accessibility of this compound class provide promising hit scaffold for medicinal chemists to further explore this series of PRMT5 inhibitors.
- Zhu, Kongkai,Shao, Jingwei,Tao, Hongrui,Yan, Xue,Luo, Cheng,Zhang, Hua,Duan, Wenhu
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p. 775 - 785
(2019/07/22)
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- Photochemical generation of the 2,2,6,6-tetramethylpiperidine-1-oxyl (TEMPO) radical from caged nitroxides by near-infrared two-photon irradiation and its cytocidal effect on lung cancer cells
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Novel caged nitroxides (nitroxide donors) with near-infrared two-photon (TP) responsive character, 2,2,6,6-tetramethyl-1-(1-(2-(4-nitrophenyl)benzofuran-6-yl)ethoxy)piperidine (2a) and its regioisomer 2b, were designed and synthesized. The one-photon (OP) (365 ± 10 nm) and TP (710–760 nm) triggered release (i.e., uncaging) of the 2,2,6,6-tetramethylpiperidine-1-oxyl (TEMPO) radical under air atmosphere were discovered. The quantum yields for the release of the TEMPO radical were 2.5% (2a) and 0.8% (2b) in benzene at ≈1% conversion of 2, and 13.1% (2a) and 12.8% (2b) in DMSO at ≈1% conversion of 2. The TP uncaging efficiencies were determined to be 1.1 GM at 740 nm for 2a and 0.22 GM at 730 nm for 2b in benzene. The cytocidal effect of compound 2a on lung cancer cells under photolysis conditions was also assessed to test the efficacy as anticancer agents. In a medium containing 100 μg mL?1 of 2a exposed to light, the number of living cells decreased significantly compared to the unexposed counterparts (65.8% vs 85.5%).
- Yamada, Ayato,Abe, Manabu,Nishimura, Yoshinobu,Ishizaka, Shoji,Namba, Masashi,Nakashima, Taku,Shimoji, Kiyofumi,Hattori, Noboru
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p. 863 - 873
(2019/04/17)
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- Activation of Michael Acceptors by Halogen-Bond Donors
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Extending earlier studies on iodine catalysis, experimental investigations show that various halogen-bond donors can also be employed to accelerate the Michael addition between trans -crotonophenone and indole. Solvent as well as counteranion effects have been analyzed, and kinetic and computational investigations provide additional insights into the mode of activation.
- Von Der Heiden, Daniel,Detmar, Eric,Kuchta, Robert,Breugst, Martin
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supporting information
p. 1307 - 1313
(2017/12/08)
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- Palladium catalysed regio- and stereoselective synthesis of (E)-4-aryl-1,3-bis(trimethylsilyl)but-3-en-1-ynes
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A practical and general synthetic approach to a series of 4-aryl-but-3-en-1-ynes is described. In the presence of palladium complexes a variety of aryl bromides (or iodides) undergo coupling with two equivalents of trimethylsilylacetylene with the formati
- Rogalski, Szymon,Kubicki, Maciej,Pietraszuk, Cezary
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p. 6192 - 6198
(2018/09/17)
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- Catalytic Activation of Trimethylsilylacetylenes: A One-Pot Route to Unsymmetrical Acetylenes and Heterocycles
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For the synthesis of unsymmetrical acetylenes, a Sonogashira coupling-deprotection-Sonogashira coupling reaction sequence is often used. Removal of protecting groups requires harsh conditions or an excess of difficult to handle and expensive reagents. Herein, we disclose a novel catalytic method for the selective deprotection of trimethylsilylacetylenes in Sonogashira reaction. The reagent hexafluorosilicic acid, an inexpensive nontoxic compound, was used to promote the selective desilylation. This method enables the efficient synthesis of unsymmetric acetylenes with other silylated functional groups present. Further possibilities of the method were explored by synthesis of heterocycles.
- Lasányi, Dániel,Mészáros, ádám,Novák, Zoltán,Tolnai, Gergely L.
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p. 8281 - 8291
(2018/06/11)
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- Synthesis of topologically constrained naphthalimide appended palladium(ii)-N-heterocyclic carbene complexes-insights into additive controlled product selectivity
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Topologically constrained naphthalimide appended Pd-NHCs were synthesized and characterized. These structurally related complexes were catalytically compared with previously synthesized Pd-NHCs in the regioselective heteroannulation of o-haloanilines and
- Panyam, Pradeep Kumar Reddy,Sreedharan, Ramdas,Gandhi, Thirumanavelan
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supporting information
p. 4357 - 4364
(2018/06/22)
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- Nucleophilic and electrophilic cyclization of N-alkyne-substituted pyrrole derivatives: Synthesis of pyrrolopyrazinone, pyrrolotriazinone, and pyrrolooxazinone moieties
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Intramolecular nucleophilic and electrophilic cyclization of N-alkyne-substituted pyrrole esters is described. Efficient routes towards the synthesis of pyrrolopyrazinone, pyrrolotriazinone and pyrrolooxazinone have been developed. First, N-alkyne-substituted pyrrole ester derivatives were synthesized. Introduction of various substituents into the alkyne functionality was accomplished by a copper-catalyzed cross-coupling reaction. Nucleophilic cyclization of N-alkyne-substituted methyl 1H-pyrrole-2-carboxylates with hydrazine afforded the 6-exo-dig/6-endo-dig cyclization products depending on the electronic nature of the substituents attached to the alkyne. On the other hand, cyclization of N-alkyne-substituted methyl 1H-pyrrole-2-carboxylates with iodine only resulted in the formation of the 6-endo-dig cyclization product regardless of the substitution of the alkyne functionality.
- Yenice, I??l,Basceken, Sinan,Balci, Metin
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supporting information
p. 825 - 834
(2017/06/20)
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- Substituent Effects That Control Conjugated Oligomer Conformation through Non-covalent Interactions
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Although understanding the conformations and arrangements of conjugated materials as solids is key to their prospective applications, predictive power over these structural factors remains elusive. In this work, substituent effects tune non-covalent interactions between side-chain fluorinated benzyl esters and main-chain terminal arenes, in turn controlling the conformations and interchromophore aggregation of three-ring phenylene-ethynylenes (PEs). Cofacial fluoroarene-arene (ArF-ArH) interactions cause twisting in the PE backbone, interrupting intramolecular conjugation as well as blocking chromophore aggregation, both of which prevent the typically observed bathochromic shift observed upon transitioning PEs from solution to solid. This work highlights two structural factors that determine whether the ArF-ArH interactions, and the resulting twisted, unaggregated chromophores, occur in these solids: (i) the electron-releasing characteristic of substituents on ArH, with more electron-releasing character favoring ArF-ArH interactions, and (ii) the fluorination pattern of the ArF ring, with 2,3,4,5,6-pentafluorophenyl favoring ArF-ArH interactions over 2,4,6-trifluorophenyl. These trends indicate that considerations of electrostatic complementarity, whether through a polar-π or substituent-substituent mechanism, can serve as an effective design principle in controlling the interaction strengths, and therefore the optoelectronic properties, of these molecules as solids.
- Sharber, Seth A.,Baral, Rom Nath,Frausto, Fanny,Haas, Terry E.,Müller, Peter,Thomas, Samuel W.
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supporting information
p. 5164 - 5174
(2017/05/04)
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- Acetylenic Scaffolding with Subphthalocyanines
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A new boron subphthalocyanine (SubPc) derivative with a terminal alkyne substituent on the central boron atom was prepared by substitution of a triflate at the boron atom with but-3-yn-1-ol. This compound was shown to be a versatile building block for metal-catalyzed coupling reactions, such as modified Glaser-Hay, Cadiot-Chodkiewicz, and Sonogashira reactions as well as the copper(I)-catalyzed azide-alkyne cycloaddition (CuAAC). For example, metal-catalyzed reactions provided access to a SubPc dimer containing a butadiyne bridging unit, two different SubPc-fullerene dyads as well as two cross-conjugated SubPc-tetraethynylethene (TEE) scaffolds. These TEEs containing two silyl-protected alkyne units are potential building blocks for further acetylenic scaffolding. The work shows how the axial position is post-functionalized in steps not involving a substitution reaction at the central boron atom, which is otherwise often used as the terminal step in axial functionalization of SubPcs.
- Gotfredsen, Henrik,Jevric, Martyn,Kadziola, Anders,Nielsen, Mogens Brondsted
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supporting information
p. 17 - 21
(2016/01/20)
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- Cleavage of the Carbon–Carbon Triple Bonds of Arylacetylenes for the Synthesis of Arylnitriles without a Metal Catalyst
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Cleavage of the carbon–carbon triple bonds of alkynes was achieved, which led to the synthesis of arylnitriles under transition-metal-free conditions. A vast range of terminal alkyne substrates underwent this reaction to provide the corresponding nitriles in moderate to good yields with good functional group tolerance.
- Lin, Yuanguang,Song, Qiuling
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supporting information
p. 3056 - 3059
(2016/07/12)
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- Transition-Metal Free Mechanochemical Approach to Polyyne Substituted Pyrroles
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In this contribution, the synthesis of long chain hexatriynyl- and octatetraynyl-substituted pyrroles in one step from 1-halopolyyne precursors is reported. The products were obtained via a mechanochemical approach by simple grinding of 1-haloalkynes with
- Pigulski, Bart?omiej,Arendt, Agata,Tomilin, Denis N.,Sobenina, Lyubov N.,Trofimov, Boris A.,Szafert, S?awomir
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p. 9188 - 9198
(2016/10/18)
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- A novel synthesis of polysubstituted chromenes from various salicylaldehydes and alkynes under mild conditions
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A novel synthesis of poly substituted chromenes from various salicylaldehydes and alkynes not having electron withdrawing substituents under mild conditions has been developed. The procedure is applicable for easily available various substituted salicylal
- Tanaka, Kenta,Hoshino, Yujiro,Honda, Kiyoshi
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supporting information
p. 2448 - 2450
(2016/05/19)
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- Palladium and copper catalyzed Sonogashira decarboxylative coupling of aryl iodides and alkynyl carboxylic acids
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A mild procedure of palladium and copper catalyzed decarboxylative cross-coupling reaction of aryl halides and alkynyl carboxylic acids has been developed. Low molecular weight acids, to introduce small building blocks, were specifically used. This method
- Maaliki, Carine,Chevalier, Yoan,Thiery, Emilie,Thibonnet, Jér?me
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supporting information
p. 3358 - 3362
(2016/07/11)
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- Palladium end-capped polyynes via oxidative addition of 1-haloalkynes to Pd(PPh3)4
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Reported here is the use of 1-haloacetylenes and 1-halopolyynes as synthons for the preparation of new palladium(II) end-capped polyynes. The 1-haloalkynes were obtained in a series of transformations from para-substituted bromoarenes that included Sonogashira coupling followed by halogenation and chain elongation via Cadiot-Chodkiewicz protocol. The key step for the synthesis of metal complexes was oxidative addition of 1-haloalkynes to Pd(PPh3)4, which allowed obtaining a series of metal compounds 1-5-CnX with carbon chains up to hexatriyne in 75-100% yield. All the compounds were characterized by NMR and HRMS or elemental analysis. The 13C spectra of the 1-haloalkynes showed interesting, although expected, shifts of the carbon chain atoms close to the halogen termini. X-ray crystal structures were obtained for three polyynes-two butadiynes (2-C4[Pd]Br and 3-C4[Pd]Br) and one hexatriyne (1-C6[Pd]Br)-and the latter is the first reported X-ray crystal structure of palladium end-capped hexatriyne.
- Gulia, Nurbey,Pigulski, Bartlomiej,Szafert, Slawomir
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supporting information
p. 673 - 682
(2015/05/12)
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- Synthesis of Long, Palladium End-Capped Polyynes through the Use of Asymmetric 1-Iodopolyynes
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The synthesis of a unique series of long, asymmetric 1-iodopolyynes (1-CnI and 2-CnI) with the sp-hybridized carbon chain up to a decapentayne is reported. These compounds were then used as substrates in reactions with Pd(PPh3/
- Pigulski, Bartlomiej,Gulia, Nurbey,Szafert, Slawomir
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p. 17769 - 17778
(2015/12/05)
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- Tunable electron acceptors based on cyclopenta[hi]aceanthrylenes
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A series of substituted cyclopenta[hi]aceanthrylene derivatives with electron donating (NH2, OCH3), neutral (H), and electron withdrawing (COOH, CF3, CN, NO2) substituents were prepared. A room-temperature Sonogashira cross-coupling reaction between 2,7-dibromocyclopenta[hi]aceanthrylene and an appropriately functionalized phenylene ethynylene precursor was utilized to access the materials that were characterized by Nuclear Magnetic Resonance Spectroscopy (NMR), cyclic voltammetry (CV), and UV-Vis spectroscopy. The highest occupied molecular orbital (HOMO) and lowest unoccupied molecular orbital (LUMO) were systematically varied when proceeding from electron donating to electron withdrawing substituents. The optical band gap was significantly altered for the most electron donating species, while little change was observed between different electron withdrawing substituents. This study demonstrates the ability to control the frontier orbital energies of this class of cyclopenta-fused polycyclic aromatic hydrocarbon materials through selective substitution.
- Zhu, Xinju,Yuan, Bingxin,Plunkett, Kyle N.
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supporting information
p. 7105 - 7107
(2015/12/01)
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- Design, Synthesis, and Evaluation of Triazole Derivatives That Induce Nrf2 Dependent Gene Products and Inhibit the Keap1-Nrf2 Protein-Protein Interaction
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The transcription factor Nrf2 regulates the expression of a large network of cytoprotective and metabolic enzymes and proteins. Compounds that directly and reversibly inhibit the interaction between Nrf2 and its main negative regulator Keap1 are potential pharmacological agents for a range of disease types including neurodegenerative conditions and cancer. We describe the development of a series of 1,4-diphenyl-1,2,3-triazole compounds that inhibit the Nrf2-Keap1 protein-protein interaction (PPI) in vitro and in live cells and up-regulate the expression of Nrf2-dependent gene products.
- Bertrand, Hélène C.,Schaap, Marjolein,Baird, Liam,Georgakopoulos, Nikolaos D.,Fowkes, Adrian,Thiollier, Clarisse,Kachi, Hiroko,Dinkova-Kostova, Albena T.,Wells, Geoff
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supporting information
p. 7186 - 7194
(2015/10/05)
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- Synthesis and biological evaluation of a novel betulinic acid derivative as an inducer of apoptosis in human colon carcinoma cells (HT-29)
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Abstract A novel family of betulinic acid analogues, carrying a triazole unit at C-3 attached through a linker, was synthesized by the application of azide-alkyne "Click reaction". These were screened for their anticancer activity against different cancer cells and normal human PBMC by MTT assay. Compound 2c [(3S)-3-{2-(4-(hydroxymethyl-1H-1,2,3-triazol-1-yl)acetyloxy}-lup-20(29)-en-28-oic acid] was found as the most potent inhibitor of cell line HT-29 with IC50 value 14.9 μM. Its role as an inducer of apoptosis was investigated in this cell line by Annexin-V/PI binding assay and by following its capability for ROS generation, depolarization of mitochondrial transmembrane potential, activation of caspases, PARP cleavage, nuclear degradation and expression of pro- and anti-apoptotic proteins. It exhibited much higher cytotoxicity than the standard drug 5-fluorouracil but showed negligible cytotoxicity towards normal PBMC. Elevated level of ROS generation, activation of caspase 3 and caspase 9, DNA fragmentation, higher expression of Bax and Bad, lower expression of Bcl2 and Bcl-xl, and increased level of Bax/Bcl-xl ratio identified 2c as a promising inducer of apoptosis that follows a mitochondria dependent pathway. Bio-physical studies indicate that compound 2c acts as a minor groove binder to the DNA.
- Chakraborty, Biswajit,Dutta, Debasmita,Mukherjee, Sanjukta,Das, Supriya,Maiti, Nakul C.,Das, Padma,Chowdhury, Chinmay
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supporting information
p. 93 - 105
(2015/08/18)
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- Sonogashira cross-coupling in a designer ionic liquid (IL) without copper, external base, or additive, and with recycling and reuse of the IL
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Application of a piperidine-appended dimethyl-imidazolium-NTf2 ionic liquid as dual solvent and base in the Sonogashira cross-coupling reaction of aryl-iodides with terminal acetylenes under mild conditions has been demonstrated. The method employs PdCl2(PPh3)2 without copper and external base. It is applicable to the synthesis of SF5-substituted diaryl- and aryl-alkyl-acetylenes, and can also be utilized for efficient homo-coupling of terminal acetylenes under aerobic conditions. The potential for recycling and reuse of this designer-IL offers an added advantage.
- Srinivas Reddy,Laali, Kenneth K.
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supporting information
p. 4807 - 4810
(2015/07/20)
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- Synthesis of 3-substituted isoindolin-1-ones via a tandem desilylation, cross-coupling, hydroamidation sequence under aqueous phase-transfer conditions
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A simple and expedient method for the synthesis of 3-methylene-isoindolin-1-ones 4 under aqueous phase-transfer conditions has been developed. Starting from 2-iodobenzamides 1 and (silyl)alkynes, the products are obtained in high yields and short reaction times (30 min) with the use of inexpensive CuCl/PPh3 catalyst system in the presence of n-Bu4NBr (TBAB) as a phase-transfer agent. Terminal alkynes are conveniently "unmasked" upon in situ desilylation under the reaction conditions. Alkynes possessing heterocyclic moieties were also found as amenable substrates. Furthermore, a one-pot process starting from 2-iodobenzamides 1, aryl halides (bromides or iodides) and trimethylsilylacetylene (TMSA) as a convenient acetylene surrogate was also shown to be feasible under Pd/Cu catalysis.
- Munoz, Socrates B.,Aloia, Alexandra N.,Moore, Alexander K.,Papp, Attila,Mathew, Thomas,Fustero, Santos,Olah, George A.,Surya Prakash
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supporting information
p. 85 - 92
(2015/12/30)
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- γ-Valerolactone as an alternative biomass-derived medium for the Sonogashira reaction
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γ-Valerolactone (GVL) can be used as an efficient and practical alternative to the banned and commonly used dipolar aprotic solvents. In this contribution GVL has been used as a non-toxic, biodegradable, biomass-derived medium, for the definition of a sim
- Strappaveccia, Giacomo,Luciani, Lorenzo,Bartollini, Elena,Marrocchi, Assunta,Pizzo, Ferdinando,Vaccaro, Luigi
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supporting information
p. 1071 - 1076
(2015/03/04)
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- Formation and in situ reactions of hypervalent iodonium alkynyl triflates to form cyanocarbenes
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The conversion of readily available silylalkynes, iodobenzene diacetate, and azide anions was utilized to form and react cyanocarbenes. A copper(ii)-catalyzed reaction was found to react in a different manner. Both of these methods benefit from the formation and in situ reaction of hypervalent iodonium alkynyl triflates in O-H insertion reactions. This journal is
- Dempsey Hyatt,Nasrallah, Daniel J.,Maxwell, Michael A.,Hairston, A. Christina F.,Abdalhameed, Manahil M.,Croatt, Mitchell P.
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supporting information
p. 5287 - 5289
(2015/03/30)
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- Visible light-mediated gold-catalysed carbon(sp2)-carbon(sp) cross-coupling
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A dual photoredox and gold-catalysed cross-coupling reaction of alkynyltrimethylsilanes and aryldiazonium tetrafluoroborates is described. The reaction proceeds through visible-light mediated oxidative addition of aryldiazoniums, transmetalation of alkynyltrimethylsilanes and aryl-alkynyl reductive elimination. Exclusive selectivity for silyl-substituted alkynes is observed, with no reactivity observed for terminal alkynes.
- Kim, Suhong,Rojas-Martin, Jaime,Toste, F. Dean
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- Chemoselective reductions of nitroaromatics in water at room temperature
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A robust and green protocol for the reduction of functionalized nitroarenes to the corresponding primary amines has been developed. It relies on inexpensive zinc dust in water containing nanomicelles derived from the commercially available designer surfactant TPGS-750-M. This mild process takes place at room temperature and tolerates a wide range of functionalities. Highly selective reductions can also be achieved in the presence of common protecting groups.
- Kelly, Sean M.,Lipshutz, Bruce H.
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supporting information
p. 98 - 101
(2014/01/23)
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- Halogen bonding of (iodoethynyl)benzene derivatives in solution
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Halogen bonding (XB) between (iodoethynyl)benzene donors and quinuclidine in benzene affords binding free enthalpies (δG, 298 K) between -1.1 and -2.4 kcal mol-1, with a strong LFER with the Hammett parameter σpara. The enthalpic dri
- Dumele, Oliver,Wu, Dino,Trapp, Nils,Goroff, Nancy,Diederich, Francois
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supporting information
p. 4722 - 4725
(2015/04/27)
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- Autotandem catalysis: Synthesis of pyrroles by gold-catalyzed cascade reaction
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A novel synthesis of substituted pyrroles by a gold(I)-catalyzed cascade reaction has been developed. The reaction proceeded with an autotandem catalysis consisting of an initial addition of gold-acetylide to an acetal moiety and was followed by gold-catalyzed 5-endo-dig cyclization and aromatization. Gold catalysts play a dual role in activating nucleophilicity or electrophilicity of terminal acetylenes by forming gold-acetylides or by π-coordination. The formal (3 + 2) annulation of two components provided a variety of substituted pyrroles in a modular fashion.
- Ueda, Hirofumi,Yamaguchi, Minami,Kameya, Hiroshi,Sugimoto, Kenji,Tokuyama, Hidetoshi
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supporting information
p. 4948 - 4951
(2015/04/27)
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- Regio- and stereoselective dimerization of arylacetylenes and optical and electrochemical studies of (E)-1,3-enynes
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The N-heterocyclic carbene palladium complex (SIPr)Pd(cinnamyl)Cl [SIPr=N,N'-bis(2,4,6-trimethylphenyl)-4,5-dihydroimidazol-2-ylidene) promotes regio- and stereospecific dimerization of a variety of arylalkynes to give (E)-1,3-enynes in good to excellent yields. An efficient and practical procedure for their synthesis was developed using a biphasic aqueous alkali/heptane system. Optical and electronic properties of (E)-1,3-enynes are highly tunable. Depending on the nature of the substituents, HOMO energies vary in the range 5.3-6.0eV. (E)-1,3-Enynes can exhibit intense photoluminescence in the spectral region 350-500nm.
- Morozov, Oleg S.,Asachenko, Andrey F.,Antonov, Denis V.,Kochurov, Vitaly S.,Paraschuk, Dmitry Yu.,Nechaev, Mikhail S.
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supporting information
p. 2671 - 2678
(2014/09/29)
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- CLASS II HMG-COA REDUCTASE INHIBITORS AND METHODS OF USE
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Disclosed are compositions and methods for treating bacterial infections.
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Paragraph 0049
(2014/01/08)
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- Ethynylbenziodoxolones (EBX) as reagents for the ethynylation of stabilized enolates
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Herein, we report a detailed study on the electrophilic alkynylation of cyclic keto esters and amides with ethynylbenziodoxolone (EBX) reagents. The structure and stability of this class of reagents is first described more in details. Differential scannin
- Fernandez Gonzalez, Davinia,Brand, Jonathan P.,Mondiere, Regis,Waser, Jerome
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supporting information
p. 1631 - 1639
(2013/07/05)
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- Palladium-catalyzed trifluoroethylation of terminal alkynes with 1,1,1-trifluoro-2-iodoethane
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An efficient Csp-CH2CF3 bond-forming reaction via Pd-catalyzed 2,2,2-trifluoroethylation of aryl and alkyl terminal alkynes has been developed. This protocol proceeds under mild conditions using the readily available and cheap reagent CF3CH2I as the source of the CH2CF3 group. Various terminal aryl alkynes as well as alkylacetylenes can be transformed into the corresponding trifluoroethylated products in good-to-excellent yields. The method is tolerant of carbonyl, nitro, ester, cyano, and even formyl groups.
- Feng, Yi-Si,Xie, Chuan-Qi,Qiao, Wen-Long,Xu, Hua-Jian
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supporting information
p. 936 - 939
(2013/03/28)
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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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supporting information
p. 1264 - 1267
(2013/03/14)
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- Rhodium-catalyzed chemo- and regioselective cross-dimerization of two terminal alkynes
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Cross-dimerization of terminal arylacetylenes and terminal propargylic alcohols/amides has been achieved in the presence of a rhodium catalyst. This method features high chemo- and regioselectivities rendering convenient and atom economical access to functionalized enynes.
- Xu, Hua-Dong,Zhang, Ren-Wei,Li, Xiaoxun,Huang, Suyu,Tang, Weiping,Hu, Wen-Hao
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supporting information
p. 840 - 843
(2013/03/29)
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- Site-specific cleavage of nucleic acids by photoreactive conjugates
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A process of forming a double strand cleavage in DNA includes providing a reaction mixture containing double stranded DNA having a break in a first strand defining a target site in a second strand. The method continues by adding to the reaction mixture a
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Page/Page column 6
(2012/08/28)
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- Ethynyl benziodoxolones for the direct alkynylation of heterocycles: Structural requirement, improved procedure for pyrroles, and insights into the mechanism
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This report describes a full study of the gold-catalyzed direct alkynylation of indoles, pyrroles, and thiophenes using alkynyl hypervalent iodine reagents, especially the study of the structural requirements of alkynyl benziodoxolones for an efficient acetylene transfer to heterocycles. An improved procedure for the alkynylation of pyrroles using pyridine as additive is also reported. Nineteen alkynyl benziodoxol(on)es were synthesized and evaluated in the direct alkynylation of indoles and/or thiophenes. Bulky silyl groups as acetylene substituents were optimal. Nevertheless, transfer of aromatic acetylenes to thiophene was achieved for the first time. An accelerating effect of a methyl substituent in both the 3-and 6-position of triisopropylsilylethynyl-1,2-benziodoxol-3(1H)-one (TIPS-EBX) on the reaction rate was observed. Competitive experiments between substrates of different nucleophilicity, deuterium labeling experiments, as well as the regioselectivity observed are all in agreement with electrophilic aromatic substitution. Gold(III) 2-pyridinecarboxylate dichloride was also an efficient catalyst for the reaction. Investigations indicated that gold(III) could be eventually reduced to gold(I) during the process. As a result of these investigations, a π activation or an oxidative mechanism are most probable for the alkynylation reaction.
- Brand, Jonathan P.,Chevalley, Clara,Scopelliti, Rosario,Waser, Jerome
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supporting information; experimental part
p. 5655 - 5666
(2012/06/01)
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- Specific interaction modes in the crystal structures of oligofluorinated tolanes featuring additional electron donor and acceptor groups
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A series of partially fluorinated and specifically para-substituted tolanes (1-4) have been synthesized via palladium-catalyzed Sonogashira cross-coupling reaction. The single-crystal structures have been determined by X-ray diffraction. The molecules ado
- Stein, Mario,Berger, Ricarda,Seichter, Wilhelm,Hulliger, Jürg,Weber, Edwin
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scheme or table
p. 231 - 239
(2012/04/04)
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- Diphenylphosphinoethane-functionalized polystyrene resin-supported Pd(0) complex ' A highly active and recyclable catalyst for the Stille reaction under aerobic conditions
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The polymer-supported palladium(II) diphenylphosphinoethane complex is a highly active catalyst that could be used for the Stille coupling reaction between aryl iodides and (or) chlorides and organostannanes at room temperature under aerobic conditions. This heterogeneous palladium catalyst is efficient, air-stable, and recyclable.
- Bahari, Siavash,Mohammadi-Aghdam, Babak,Molaei, Rahim,Gharibi, Zakiyeh
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p. 784 - 789
(2012/11/07)
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- DIPEPTIDE ACETYLENE CONJUGATES AND A METHOD FOR PHOTOCLEAVAGE OF DOUBLE STRAND DNA BY DIPEPTIDE ACETYLENE CONJUGATES
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Photoreactive DNA cleaving conjugate compounds are provided comprising a DNA cleaving moiety which comprises an aryl alkyne group and a polyfunctional pH-regulated DNA-binding moiety which comprises at least one or two amino groups.
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Page/Page column 16
(2012/12/13)
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- The synthesis, characterization and third-order nonlinear optical character of poly(2,5-dipropargyloxybenzoate) containing a polar aromatic diacetylene
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The glass transition temperature of the novel compound, poly(2,5-dipropargyloxybenzoate) containing a polar aromatic diacetylene was 105 °C and differential scanning calorimetry showed two exothermic peaks due to the opening of the hexa-2,4-diynylene-1,6-
- Casta?on, Sandra L.,Beristain, Miriam F.,Ortega, Alejandra,Gómez-Sosa, Gustavo,Mu?oz, Eduardo,Perez-Martínez, Ana Laura,Ogawa, Takeshi,Halim, M. Faisal,Smith, Francis,Walser, Ardie,Dorsinville, Roger
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scheme or table
p. 129 - 134
(2011/01/12)
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- One-pot click synthesis of 1N-alkyl-4-aryl-1,2,3-triazoles from protected arylalkynes and alkyl bromides
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1N-Alkyl-4-aryl-1,2,3-triazoles have been prepared through a multicomponent one-pot protocol from the corresponding (arylethynyl)trimethylsilanes and alkyl bromides. In situ alkyl azide formation and alkyne deprotection followed by copper(I)-catalyzed click cycloaddition afforded the desired 1,4-disubstituted 1,2,3-triazoles in generally good to excellent yield, with only minor observation of the undesired 1,5-regioisomeric cycloadduct. The protocol eliminates the need to use reactive organic azides and terminal alkynes. Georg Thieme Verlag Stuttgart. New York.
- Ladouceur, Sebastien,Soliman, Ahmed M.,Zysman-Colman, Eli
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supporting information; experimental part
p. 3604 - 3611
(2011/12/16)
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- Fine-tuning alkyne cycloadditions: Insights into photochemistry responsible for the double-strand DNA cleavage via structural perturbations in diaryl alkyne conjugates
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Hybrid molecules combining photoactivated aryl acetylenes and a dicationic lysine moiety cause the most efficient double-strand (ds) DNA cleavage known to date for a small molecule. In order to test the connection between the alkylating ability and the DN
- Yang, Wang-Yong,Marrone, Samantha A.,Minors, Nalisha,Zorio, Diego A.R.,Alabugin, Igor V.
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scheme or table
p. 813 - 823
(2011/08/10)
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- Metal-free 1,5-regioselective azide-alkyne [3+2]-cycloaddition
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[3+2]-cycloaddition reactions of aromatic azides and silylated alkynes in aqueous media yield 1,5-disubstituted-4-(trimethyl-silyl)-1H-1,2,3-triazoles. The formation of the 1,5-isomer is highly favored in this metal-free cycloaddition, which could be proven by 1D selective NOESY and X-ray investigations. Additionally, DFT calculations corroborate the outstanding favoritism regarding the 1,5-isomer. The described method provides a simple alternative protocol to metal-catalyzed "click chemistry" procedures, widening the scope for regioselective heavy-metal-free synthetic applications.
- Kloss, Florian,Koehn, Uwe,Jahn, Burkhard O.,Hager, Martin D.,Goerls, Helmar,Schubert, Ulrich S.
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supporting information; experimental part
p. 2816 - 2824
(2012/06/01)
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- One-pot three-step synthesis of 1,2,3-triazoles by copper-catalyzed cycloaddition of azides with alkynes formed by a Sonogashira cross-coupling and desilylation
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A microwave-assisted, one-pot, three-step Sonogashira cross-coupling- desilylation-cycloaddition sequence was developed for the convenient preparation of 1,4-disubstituted 1,2,3-triazoles starting from a range of halides, acyl chlorides, ethynyltrimethyls
- Friscourt, Frederic,Boons, Geert-Jan
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supporting information; experimental part
p. 4936 - 4939
(2010/12/25)
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- Synthesis, characterization and DFT calculations of new ethynyl-bridged C60 derivatives
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A new series of soluble C60 derivatives for organic electronic application has been synthesized by ethynylation reaction using different electron-donating and electron-withdrawing groups of varying length.
- Rondeau-Gagné, Simon,Curutchet, Carles,Grenier, Fran?ois,Scholes, Gregory D.,Morin, Jean-Fran?ois
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experimental part
p. 4230 - 4242
(2010/07/08)
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- Site-specific cleavage of nucleic acids by photoreactive conjugates
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A process of forming a double strand cleavage in DNA includes providing a reaction mixture containing double stranded DNA having a break in a first strand defining a target site in a second strand. The method continues by adding to the reaction mixture a
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