- N2/CO Exchange at a Vinylidene Carbon Center: Stable Alkylidene Ketenes and Alkylidene Thioketenes from 1,2,3-Triazole Derived Diazoalkenes
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We present a new class of room-temperature stable diazoalkenes featuring a 1,2,3-triazole backbone. Dinitrogen of the diazoalkene moiety can be thermally displaced by an isocyanide and carbon monoxide. The latter alkylidene ketenes are typically considered as highly reactive compounds, traditionally only accessible by flash vacuum pyrolysis. We present a new and mild synthetic approach to the first structurally characterized alkylidene ketenes by a substitution reaction. Density functional theory calculations suggest the substitution with isocyanides to take place via a stepwise addition/elimination mechanism. In the case of carbon monoxide, the reaction proceeds through an unusual concerted exchange at a vinylidene carbon center. The vinylidene ketenes react with carbon disulfide via a four-membered thiete intermediate to give vinylidene thioketenes under release of COS. We present spectroscopic as well as structural data for the complete isoelectronic series (R2C═C═X; X = N2, CO, CNR, CS) including 1J(13C-13C) data. As N2, CO, and isocyanides belong to the archetypical ligands in transition-metal chemistry, this process can be interpreted in analogy to coordination chemistry as a ligand exchange reaction at a vinylidene carbon center.
- Antoni, Patrick W.,Hansmann, Max M.,Reitz, Justus
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supporting information
p. 12878 - 12885
(2021/08/24)
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- Direct Synthesis of 1-Arylprop-1-ynes with Calcium Carbide as an Acetylene Source
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A simple method is described for the synthesis of 1-arylprop-1-ynes directly from aromatic aldehyde p -tosylhydrazones by using calcium carbide as an acetylene source. The salient features of this protocol are its use of a readily available and easily handled source of acetylene, its operational simplicity, its high yield, and its broad substrate scope.
- Gao, Lei,Li, Zheng
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supporting information
p. 1580 - 1584
(2019/08/20)
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- A Pd-catalyzed domino Larock annulation/dearomative Heck reaction
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A palladium-catalyzed domino Larock annulation/dearomative Heck reaction is developed, which delivers a range of tetracyclic indoline derivatives in moderate to excellent yields through a Larock annulation of N-bromobenzoyl o-iodoanilines with alkynes and a subsequent intramolecular dearomative Heck reaction. This protocol provides a straightforward route to structurally diverse indolines from readily available starting materials by forming two new rings and three chemical bonds in a single step.
- Liang, Ren-Xiao,Xu, Deng-Yun,Yang, Fu-Ming,Jia, Yi-Xia
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supporting information
p. 7711 - 7714
(2019/07/09)
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- Multi-Metal-Catalyzed Oxidative Radical Alkynylation with Terminal Alkynes: A New Strategy for C(sp3)-C(sp) Bond Formation
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A new way for C(sp3)-C(sp) cross-coupling with terminal alkynes has been developed by using a multi-metal-catalyzed reaction strategy. Alkyl radicals generated from different approaches are able to couple with terminal alkynes by judicious selection of the catalyst combination. This reaction protocol offers an efficient alternative approach for the synthesis of substituted alkynes from terminal alkynes besides traditional Sonogashira coupling. Mechanistic studies have also been carried out to clarify the role of each metal catalyst in the radical alkynylation processes. The reactions were found to go through radical reaction pathways. Synergistic cooperation of the metal catalysts is the key for controlling the reaction selectivity of alkyl radicals toward C(sp3)-C(sp) bond formation.
- Tang, Shan,Liu, Yichang,Gao, Xinlong,Wang, Pan,Huang, Pengfei,Lei, Aiwen
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supporting information
p. 6006 - 6013
(2018/05/14)
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- Visible-Light-Mediated Photoredox-Catalyzed Regio- and Stereoselective Chlorosulfonylation of Alkynes
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Herein, a one-step chlorosulfonylation of alkynes via a photocatalytic redox process is described. A variety of commercially available sulfonyl chlorides can be applied for the generation of sulfonyl radical species under visible-light irradiation. Regio- and stereoselective addition of the sulfonyl radical and chloride leads to the efficient formation of (E)-selective β-chlorovinyl sulfones from a broad range of terminal and internal alkynes. The reported method represents an operationally simple and mild way to furnish vinyl sulfones.
- Chakrasali, Prashant,Kim, Kyuneun,Jung, Young-Sik,Kim, Hyejin,Han, Soo Bong
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supporting information
p. 7509 - 7513
(2019/01/03)
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- Multicomponent Oxidative Trifluoromethylation of Alkynes with Photoredox Catalysis: Synthesis of α-Trifluoromethyl Ketones
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The direct oxidative addition of CF3 and H2O to alkynes was achieved with photoredox catalysis to obtain α-trifluoromethyl ketones via rapid enol-keto tautomerization. The reaction exhibits high functional group tolerance and regioselectivity. Heterocycles of various sizes containing CF3 were synthesized from the α-CF3-substituted diketones obtained through the protocol, thereby demonstrating the versatile applicability of the method. Mechanistic studies of the reaction with isotopes provided insight into the reaction pathway.
- Malpani, Yashwardhan R.,Biswas, Bishyajit Kumar,Han, Hong Sik,Jung, Young-Sik,Han, Soo Bong
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supporting information
p. 1693 - 1697
(2018/04/16)
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- High Oxidation State Molybdenum N-Heterocyclic Carbene Alkylidyne Complexes: Synthesis, Mechanistic Studies, and Reactivity
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The first synthetic protocol to high oxidation state molybdenum(VI) N-heterocyclic carbene (NHC) alkylidyne complexes (NHC=1,3-diisopropylimidazol-2-ylidene, 1,3-dimethyl-4,5-R2-imidazol-2-ylidene, R2=H, Cl, CN) is reported. Steric limitations of the NHCs and the benzylidyne are described. All novel complexes were characterized by single crystal X-ray diffraction and solution NMR techniques. It was shown that all complexes presented here show activity in the self-metathesis of 1-phenyl-1-propyne at room temperature. To identify mechanistic differences, an experimental sequence to detect dissociation of ligands was developed. Results reveal dissociation of less electron-donating NHCs in course of the reaction. Mechanistic and reactivity differences were attributed to electronic and steric effects through Tolman's electronic parameter and the percentage of buried volume. Furthermore, Mo-1 containing the 1,3-dimethylimidazol-2-ylidene ligand showed good activity in self-metathesis reactions of p-substituted 1-phenyl-1-propynes with electron-donating moieties at room temperature.
- Koy, Maximilian,Elser, Iris,Meisner, Jan,Frey, Wolfgang,Wurst, Klaus,K?stner, Johannes,Buchmeiser, Michael R.
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supporting information
p. 15484 - 15490
(2017/11/09)
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- Stereoselective Photoredox-Catalyzed Chlorotrifluoromethylation of Alkynes: Synthesis of Tetrasubstituted Alkenes
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A new photoredox-catalyzed chlorotrifluoromethylation reaction of internal arylalkynes under mild conditions using visible light has been developed. The reactions proceed with high levels of regio- and stereoselectivity and utilize commercially available CF3SO2Cl as both the CF3 and Cl source. In the mechanistic pathway for this process, generation of the CF3 radical and chloride ion occurs by Ir(ppy)3-photocatalyzed reductive decomposition of CF3SO2Cl. The synthetically important trifluoromethyl-substituted vinyl chlorides produced in this process can be readily transformed to 1,1-bis-arylalkenes by using Suzuki coupling.
- Han, Hong Sik,Lee, Young Jin,Jung, Young-Sik,Han, Soo Bong
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supporting information
p. 1962 - 1965
(2017/04/28)
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- BIMESOGENIC COMPOUNDS AND MESOGENIC MEDIA
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The invention relates to bimesogenic compounds of formula I wherein R11, R12, MG11, MG12, X11, X12 and Sp1 have the meaning given in claim 1, to the use of bimesogenic compounds of formula I in liquid crystal media and particular to flexoelectric liquid crystal devices comprising a liquid crystal medium according to the present invention.
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Paragraph 0238-0240
(2017/12/15)
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- Synthesis of diarylenynes by olefination of 1-arylpropyne with arylaldehyde and their optical properties
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A new synthetic protocol of 1-arylpropyne was developed by taking advantage of 1-(diphenylphosphoryl)propyne as propyne equivalent in Sonogashira coupling: consecutive subjection of phosphorylpropyne to t-BuOK and to aryl halides in the presence of Pd and Cu catalysts afforded the corresponding 1-arylpropynes. The following olefination of the 1-arylpropyne with aldehyde provided the corresponding diarylenyne. When the enynes thus obtained were irradiated with UV light, they showed strong emission in organic solvents and in the solid states. In solution, Ph2N-substituted enynes exhibited remarkable solvatofluorochromism, and Lippert–Mataga plot analysis demonstrated that they undergo the larger polarization in the excited states than in the ground states.
- Shinohara, Kenta,Nishida, Takanori,Wada, Ryosuke,Peng, Lifen,Minoda, Yuju,Orita, Akihiro,Otera, Junzo
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p. 4427 - 4434
(2016/07/06)
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- HETEROCYCLIC MODULATORS OF LIPID SYNTHESIS AND COMBINATIONS THEREOF
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Heterocyclic modulators of lipid synthesis are provided as well as pharmaceutically acceptable salts thereof; pharmaceutical compositions comprising such compounds; and methods of treating conditions characterized by disregulation of a fatty acid synthase pathway by the administration of such compounds and combinations of such compounds and other therapeutic agents.
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Page/Page column 160; 161
(2015/07/07)
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- HETEROCYCLIC MODULATORS OF LIPID SYNTHESIS
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Heterocyclic modulators of lipid synthesis are provided as well as pharmaceutically acceptable salts thereof; pharmaceutical compositions comprising such compounds; and methods of treating conditions characterized by disregulation of a fatty acid synthase pathway by the administration of such compounds.
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Page/Page column 145; 146
(2014/01/18)
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- Palladium-catalyzed methylation of alkynyl C(sp)-H bonds with dimethyl sulfonium ylides
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A novel palladium-catalyzed methylation protocol for the synthesis of methyl-functionalized internal alkynes has been established. This methylation method is achieved through a C(sp)-C(sp3) bond formation process and represents a new synthetic application of sulfonium ylides.
- Liu, Yan-Yun,Yang, Xu-Heng,Huang, Xiao-Cheng,Wei, Wen-Ting,Song, Ren-Jie,Li, Jin-Heng
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p. 10421 - 10426
(2013/11/06)
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- A versatile synthesis of functionalized pentahelicenes
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A general synthetic methodology for the preparation of functionalized (hetero)helicenes has been developed. It employs the sequence of a double propargyl organometallics (Li, Mg, Ga/In) addition to a tolan-2,2′- dialdehyde-type intermediate, a cobalt-catalyzed/cobalt-mediated [2 + 2 + 2] cycloisomerization of a triyne intermediate, and a double silica gel-assisted acetic acid elimination to receive pentahelicene, 1,14-diazapentahelicene, and 3,12-dichloro-, 3,12-dichloro-7-trimethylsilyl-, and 3,12-di-tert- butylpentahelicene. 3,12-Dichloropentahelicene undergoes a Suzuki-Miyaura coupling with aryl boronic acids (or ester) under palladium catalysis to afford 3,12-diarylpentahelicenes.
- Songis, Olivier,Misek, Jiri,Schmid, Markus B.,Kollarovic, Adrian,Stara, Irena G.,Saman, David,Cisarova, Ivana,Stary, Ivo
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experimental part
p. 6889 - 6899
(2010/11/18)
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- Convenient synthesis of (1-propynyl)arenes through a one-pot double elimination reaction, and their conversion to enynes
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A series of (1-propynyl)arenes were prepared by one-pot double elimination reaction of ethyl sulfone, aromatic aldehyde and chloro diethylphosphate in THF with a base such as BuLi and t-BuOK. A propargyllithium which was prepared by treatment of (1-propynyl)arene with BuLi in the presence of 1,3-dimethyl-3,4,5, 6-tetrahydro-2(1H)-pyrimidinone (DMPU) reacted with aromatic aldehyde, chloro diethylphosphate and t-BuOK to afford (4-arylbut-3-en-1-ynyl)arene. Photoluminescence of the enynes thus prepared was recorded both in solution and in the solid state. Georg Thieme Verlag Stuttgart.
- An, De-Lie,Zhang, Zhiyang,Orita, Akihiro,Mineyama, Hidetaka,Otera, Junzo
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p. 1909 - 1912
(2008/03/13)
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- Alkyne metathesis with simple catalyst systems: High yield dimerization of propynylated aromatics; scope and limitations
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High yield dimerization of propynylated benzenes and propynylnaphthalene by a mixture of Mo(CO)6 and 4-chlorophenol at 140 °C in 1,2-dichlorobenzene is reported to give the corresponding disubstituted alkynes. The scope and limitation of the reaction and the influence of substitution pattern and substitution type are discussed. Oxygen or nitrogen carrying substrates metathesize in moderate to good yields and ortho-alkyl substituted examples form the respective tolanes very efficiently.
- Pschirer, Neil Gregory,Bunz, Uwe H. F.
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p. 2481 - 2484
(2007/10/03)
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