- Iron-Catalyzed Vinylzincation of Terminal Alkynes
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Organozinc reagents are among the most commonly used organometallic reagents in modern synthetic chemistry, and multifunctionalized organozinc reagents can be synthesized from structurally simple, readily available ones by means of alkyne carbozincation. However, this method suffers from poor tolerance for terminal alkynes, and transformation of the newly introduced organic groups is difficult, which limits its applications. Herein, we report a method for vinylzincation of terminal alkynes catalyzed by newly developed iron catalysts bearing 1,10-phenanthroline-imine ligands. This method provides efficient access to novel organozinc reagents with a diverse array of structures and functional groups from readily available vinylzinc reagents and terminal alkynes. The method features excellent functional group tolerance (tolerated functional groups include amino, amide, cyano, ester, hydroxyl, sulfonyl, acetal, phosphono, pyridyl), a good substrate scope (suitable terminal alkynes include aryl, alkenyl, and alkyl acetylenes bearing various functional groups), and high chemoselectivity, regioselectivity, and stereoselectivity. The method could significantly improve the synthetic efficiency of various important bioactive molecules, including vitamin A. Mechanistic studies indicate that the new iron-1,10-phenanthroline-imine catalysts developed in this study have an extremely crowded reaction pocket, which promotes efficient transfer of the vinyl group to the alkynes, disfavors substitution reactions between the zinc reagent and the terminal C–H bond of the alkynes, and prevents the further reactions of the products. Our findings show that iron catalysts can be superior to other metal catalysts in terms of activity, chemoselectivity, regioselectivity, and stereoselectivity when suitable ligands are used.
- Huang, Qiang,Su, Yu-Xuan,Sun, Wei,Hu, Meng-Yang,Wang, Wei-Na,Zhu, Shou-Fei
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p. 515 - 526
(2022/01/08)
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- Regio- and stereoselective synthesis of bromoalkenes by homolytic hydrobromination of alkynes with hydrogen bromide
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Homolytic hydrobromination of terminal and internal alkynes with a commercially available solution of hydrogen bromide in acetic acid has been investigated for regio- and stereoselective synthesis of bromoalkenes. Under an aerobic atmosphere at room temperature, the reaction of ethynylarenes with a small excess of HBr efficiently gave (2-bromoethenyl)arenes with good to high E-selectivity. (Alk-1-ynyl)arenes, or internal alkynes bearing both phenyl and alkyl groups at the sp-carbons also underwent the air-initiated hydrobromination to exhibit high Z-selectivity under kinetic conditions using a half equivalent of HBr.
- Kinoshita, Hidenori,Kumaki, Wataru,Miura, Katsukiyo
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- 1,2-Carbopentafluorophenylation of Alkynes: The Metallomimetic Pull-Push Reactivity of Tris(pentafluorophenyl)borane
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We report the novel single-step 1,2-dicarbofunctionalization of an arylacetylene with an allylsilane and tris(pentafluorophenyl)borane [B(C6F5)3] involving C?C bond formation with C?H bond scission at the β-position to the silicon atom of an allylsilane and B→C migration of a C6F5 group. The 1,2-carbopentafluorophenylation occurs smoothly without the requirement for a catalyst or heating. Mechanistic studies suggest that the metallomimetic “pull-push” reactivity of B(C6F5)3 imparts consecutive electrophilic and nucleophilic characteristics to the benzylic carbon of the arylacetylene. Subsequent photochemical 6π-electrocyclization affords tetrafluoronaphthalenes, which are important in the pharmaceutical and materials sciences. Owing to the unique reactivity of B(C6F5)3, the 1,2-carbopentafluorophenylation using 2-substituted furan proceeded with ring opening, and the reaction using silyl enolates formed a C?C bond with C?O bond scission at the silyloxy-substituted carbon.
- Shibuya, Masatoshi,Matsuda, Miki,Yamamoto, Yoshihiko
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supporting information
p. 8822 - 8831
(2021/05/21)
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- Polycyclic aromatic hydrocarbon-substituted push-pull chromophores: An investigation of optoelectronic and nonlinear optical properties using experimental and theoretical approaches
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A series of new push-pull chromophores were synthesized in moderate to very high yields (65%-97%) by treating TCNE and TCNQ with alkynes substituted by electron-rich diethylaniline and polycyclic aromatic hydrocarbons. Some of the chromophores exhibit strong intramolecular charge-transfer bands in the near-IR region with λmax values between 695 and 749 nm. With the help of experimental and theoretical analysis, it is concluded that the trend in λmax values is affected by PAH substituents sterically, not electronically. Steric constraints led to the increased dihedral angles, reducing conjugation efficiencies. The absorption properties of push-pull compounds have been investigated in solvents possessing different polarities. All chromophores exhibited positive solvatochromism. As an additional proof of efficient charge-transfer in push-pull chromophores, quinoid character (dr) values were predicted using calculated bond lengths. Remarkably, substantial dr values (0.045-0.049) were predicted for donor diethylaniline rings in all compounds. The effects of various polycyclic aromatic hydrocarbons on optical and nonlinear optical properties were also studied by computational methods. Several parameters, such as band gaps, Mulliken electronegativity, chemical hardness and softness, dipole moments, average polarizability, first hyperpolarizability, were predicted for chromophores at the B3LYP/6-31++G(d,p) level of theory. The predicted first hyperpolarizability β(tot) values vary between 198 to 538 × 10-30 esu for the reported push-pull chromophores in this study. The highest predicted β(tot) value in this study is 537.842 × 10-30 esu, 8150 times larger than the predicted β(tot) value of benchmark NLO material urea, suggests possible utilization of these chromophores in NLO devices. The charge-transfer character of the synthesized structures was further confirmed by HOMO-LUMO depictions and electrostatic potential maps.
- Dengiz, ?a?atay
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p. 1375 - 1390
(2021/10/26)
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- Cu-mediated or metal-free alkylation of gem-dibromoalkenes with tertiary, secondary and primary alkyl Grignard reagents
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A novel copper-mediated or transition-metal-free alkylation of gem-dibromoalkenes with tertiary, secondary and primary alkyl Grignard reagents was described. The outcomes of these reactions were found to be highly dependent on the reaction conditions and
- Deng, Yupian,Zhang, Xuxue,Liu, Chuan,Cao, Song
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- Synthesis of alkynes under dry reaction conditions
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An easy synthetic method was developed under dry reaction conditions for the preparation of terminal alkynes from 1,1-dibromoalkenes and in the presence of succinimide which acts as a nucleophile and proton donor. It was demonstrated with the synthesis of a broad spectrum of terminal alkynes and extended to synthesize internal alkynes under tandem reaction conditions.
- Rao, Maddali L.N.,Shamim Islam, Sk
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supporting information
(2021/04/19)
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- Tertiary amines acting as Alkyl radical equivalents enabled by a P/N heteroleptic Cu(I) photosensitizer
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An unprecedented exploration of tertiary amines as alkyl radical equivalents for cross-coupling with aromatic alkynes to access allylarenes has been achieved by a P/N heteroleptic Cu(I)based photosensitizer under photoredox catalysis conditions. Mechanist
- Zheng, Limeng,Jiang, Qinfang,Bao, Hanyang,Zhou, Bingwei,Luo, Shu-Ping,Jin, Hongwei,Wu, Huayue,Liu, Yunkui
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p. 8888 - 8893
(2020/11/30)
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- Grignard-Reagent-Promoted Desulfonylation/Intramolecular Coupling for the Synthesis of 2-(1-Fluorovinyl)pyridines
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A novel process involving Grignard-reagent-promoted desulfonylation/intramolecular coupling of readily available α-fluoro-α,β-unsaturated-(2-pyridyl)sulfones was realized that provided a series of polysubstituted 2-(1-fluorovinyl)pyridines in good yields. The intrinsic coordination between pyridine and Mg(II) along with the "negative fluorine effect"of the substrates should play the key role for the smooth transformation in the absence of transition-metal catalysts.
- Jiang, Gaoxi,Kang, Lei,Qian, Jinlong,Yang, Huameng,Zhang, Jinlong
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supporting information
p. 9118 - 9122
(2020/12/02)
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- Perylene Bisimide and Naphthyl-Based Molecular Dyads: Hydrogen Bonds Driving Co-planarization and Anomalous Temperature-Response Fluorescence
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The origin of the positive temperature effect in fluorescence emission of a newly designed perylene bisimide (PBI) derivative with two naphthyl units containing ortho-methoxy group (NM) at its bay positions (PBI-2NM) was elucidated. A key point is the finding of a weak hydrogen bond (?1) between the methoxy group of the NM unit and a nearby hydrogen atom of the PBI core. It is the bonding that drives co-planarization of the different aromatic units, resulting in delocalization of the π-electrons of the compound as synthesized, inducing fluorescence quenching via intramolecular charge transfer (ICT). With increasing temperature, the co-planar structure could be distorted in part, resulting in a decreased degree of ICT, and hence leading to enhanced fluorescence emission. The unique positive temperature effect in emission induced by H-bond-driven co-planarization may pave a new avenue in designing functional molecular systems complementary to conventional methods.
- Chou, Pi-Tai,Fang, Yu,Jiang, Qingwei,Liu, Fengyi,Liu, Ke,Shang, Congdi,Wang, Gang
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p. 8579 - 8585
(2020/03/24)
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- Method for synthesizing 1,5-benzodiazepine compound
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The invention discloses a method for synthesizing a 1,5-benzodiazepine compound. The method specifically comprises the following steps: dissolving a gold catalyst, an additive, alkyne of a formula IIshown in the specification, an o-phenylenediamine derivative of a formula III shown in the specification into an organic solvent, putting the solution into a pressure-resistant reaction tube, performing a stirring reaction for 6-24 hours at 25 DEG C so as to obtain a reaction liquid, and performing aftertreatment on the reaction liquid so as to obtain the 1,5-benzodiazepine compound of a formula IV shown in the specification, wherein the mass ratio of the gold catalyst of a formula I shown in the specification to the additive to the alkyne of the formula II shown in the specification to the o-phenylenediamine derivative of the formula III shown in the specification is (0.01-0.07):(0-0.1):(2.0-3.0):1. By adopting the method disclosed by the invention, a double-functional catalyst is used, the reaction can be performed under a room temperature condition, and thus energy consumption can be reduced; and the method has the advantages of being small in catalyst amount, high in yield, good insubstrate universality, simple and convenient in operation, and the like.
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- BF3·OEt2-Promoted Propargyl Alcohol Rearrangement/[1,5]-Hydride Transfer/Cyclization Cascade Affording Tetrahydroquinolines
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An efficient BF3·OEt2-mediated propargyl alcohol rearrangement/[1,5]-hydride transfer/cyclization cascade for the synthesis of tetrahydroquinoline derivatives has been described. The substituents adjacent to triple bonds play an important role in the formation of ketones (via [1,3]-hydroxyl shift) or alkenyl fluorides which are products of formal trans-carbofluorination of internal alkynes. This method provides a rapid access to diverse heterocycles in moderate to excellent yields.
- Zhao, Shuang,Wang, Xiaoyang,Wang, Pengfei,Wang, Guangwei,Zhao, Wentao,Tang, Xiangyang,Guo, Minjie
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supporting information
p. 3990 - 3993
(2019/06/14)
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- Copper-Mediated Deacylative Coupling of Ynones via C-C Bond Activation under Mild Conditions
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The intermolecular deacylative coupling of unstrained ynones via C-C bond activation was accomplished by a CuCl-bpy system under mild reaction conditions. This protocol features facile cleavage of the C-C bond at room temperature, broad substrate scope, and efficient construction of important symmetric and unsymmetrical 1,3-diyne adducts through homo or cross coupling of ynones, respectively. The preliminary mechanistic investigations indicated that an acyl copper(III) complex is likely involved in this process.
- Feng, Lili,Hu, Tingjun,Zhang, Saisai,Xiong, Heng-Ying,Zhang, Guangwu
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p. 9487 - 9492
(2019/12/02)
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- Copper-Catalyzed Ring Opening of [1.1.1]Propellane with Alkynes: Synthesis of Exocyclic Allenic Cyclobutanes
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Despite the long history and interesting properties of propellanes, these compounds still have tremendous potential to be exploited in synthetic organic chemistry. Herein we disclose an experimentally simple procedure to achieve cyclobutane-containing allenes and alkynes through a copper-catalyzed ring opening of [1.1.1]propellane and subsequent reaction with ethynes.
- Lasányi, Dániel,Tolnai, Gergely L.
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supporting information
p. 10057 - 10062
(2019/12/24)
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- SO2F2-Mediated Oxidative Dehydrogenation and Dehydration of Alcohols to Alkynes
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Direct synthesis of alkynes from inexpensive, abundant alcohols was achieved in high yields (greater than 40 examples, up to 95% yield) through a SO2F2-promoted dehydration and dehydrogenation process. This straightforward transformation of sp3-sp3 (C-C) bonds to sp-sp (C=C) bonds requires only inexpensive and readily available reagents (no transition metals) under mild conditions. The crude alkynes are sufficiently free of impurities to permit direct use in further transformations, as illustrated by regioselective Huisgen alkyne-azide cycloaddition reactions with PhN3 to give 1,4-substituted 1,2,3-traiazoles (16 examples, up to 92% yield) and Sonogashira couplings (10 examples, up to 77% yield).
- Zha, Gao-Feng,Fang, Wan-Yin,Li, You-Gui,Leng, Jing,Chen, Xing,Qin, Hua-Li
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supporting information
p. 17666 - 17673
(2019/01/04)
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- Gold(i)-catalyzed cross-coupling reactions of aryldiazonium salts with organostannanes
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Gold(i)-catalyzed cross-coupling reactions of aryldiazonium salts with organostannanes are described. This redox neutral strategy offers an efficient approach to diverse biaryls, vinyl arenes and arylacetylenes. Monitoring the reaction with NMR and ESI-MS provided strong evidence for the in situ formation of Ph3PAuIR (R = aryl, vinyl and alkynyl) species which is crucial for the activation of aryldiazonium salts.
- Akram, Manjur O.,Shinde, Popat S.,Chintawar, Chetan C.,Patil, Nitin T.
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supporting information
p. 2865 - 2869
(2018/05/03)
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- Electrochemically modified Corey-Fuchs reaction for the synthesis of arylalkynes. the case of 2-(2,2-dibromovinyl)naphthalene
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The electrochemical reduction of 2-(2,2-dibromovinyl)naphthalene in a DMF solution (Pt cathode) yields selectively 2-ethynylnaphthalene or 2-(bromoethynyl)naphthalene in high yields, depending on the electrolysis conditions. In particular, by simply changing the working potential and the supporting electrolyte, the reaction can be directed towards the synthesis of the terminal alkyne (Et4NBF4) or the bromoalkyne (NaClO4). This study allowed to establish that 2-(bromoethynyl)naphthalene can be converted into 2-ethynylnaphthalene by cathodic reduction.
- Pandolfi, Fabiana,Chiarotto, Isabella,Feroci, Marta
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supporting information
p. 891 - 899
(2018/04/30)
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- Metal-free synthesis of imidazole by BF3·Et2O promoted denitrogenative transannulation of N-sulfonyl-1,2,3-triazole
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BF3·Et2O promoted metal-free denitrogenative transannulation of N-sulfonyl-1,2,3-triazole was reported. Rather than transition metals, BF3·Et2O was employed for the first time to promote the formation of α-diazoimines from N-sulfonyl-1,2,3-triazoles in nitriles, leading to the synthesis of various imidazoles. The protocol tolerates a broad range of functional groups and could also be applied to the late-stage modification of bioactive molecules, demonstrating the potential of this protocol in organic synthesis. A plausible mechanism was proposed.
- Yang, Dongdong,Shan, Lihong,Xu, Ze-Feng,Li, Chuan-Ying
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p. 1461 - 1464
(2018/03/08)
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- Synthetic and Mechanistic Investigation of an Oxime Ether Electrocyclization Approach to Heteroaromatic Boronic Acid Derivatives
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A range of functionalized heteroaromatic boronic acid derivatives are readily accessed by a diboration/6π-electrocyclization sequence. This study revealed the surprising observation that there is a direct relationship between oxime ether stereochemistry and reactivity towards electrocyclization. Specifically, E-oxime ethers are found to be significantly more reactive than their Z-counterparts (stereochemistry relative to azatriene scaffold). In contrast, the configuration at the azatriene alkene terminus has little impact on reaction rates. Computational analysis offers a rationale for this observation; a Nlone pair→C=C π* orbital interaction lowers the energy of the transition state in the electrocyclization of E-oxime ethers. Finally, unreactive Z-oxime ethers can be converted to the corresponding heterocyclic products by a photolytically promoted E→Z isomerization and electrocyclization sequence.
- Mora-Radó, Helena,Sotorríos, Lia,Ball-Jones, Matthew P.,Bialy, Laurent,Czechtizky, Werngard,Méndez, María,Gómez-Bengoa, Enrique,Harrity, Joseph P. A.
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p. 9530 - 9534
(2018/07/14)
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- Fused compounds and including the organic light-emitting device
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A condensation compound is represented by Formula 1, 2, or 3 where R1 to R24 and A to F are further defined in the detailed description.
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- Antitubercular Bis-Substituted Cyclam Derivatives: Structure-Activity Relationships and in Vivo Studies
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We recently reported the discovery of nontoxic cyclam-derived compounds that are active against drug-resistant Mycobacterium tuberculosis. In this paper we report exploration of the structure-activity relationship for this class of compounds, identifying
- Spain, Malcolm,Wong, Joseph K.-H.,Nagalingam, Gayathri,Batten, James M.,Hortle, Elinor,Oehlers, Stefan H.,Jiang, Xiao Fan,Murage, Hasini E.,Orford, Jack T.,Crisologo, Patrick,Triccas, James A.,Rutledge, Peter J.,Todd, Matthew H.
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p. 3595 - 3608
(2018/05/01)
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- Au-Catalyzed Intermolecular [2+2] Cycloadditions between Chloroalkynes and Unactivated Alkenes
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The [2+2] cycloaddition is a versatile strategy for the synthesis of strained cyclobutenes of high synthetic value. In this study, two efficient intermolecular [2+2] cycloadditions between two different types of chloroalkynes and unactivated alkene are realized with gold catalysis. Of significance is that the reaction works with challenging monosubstituted unactivated alkenes, which is unprecedented in gold catalysis and scarcely documented in other metal-catalyzed/promoted reactions; moreover, the reaction exhibits excellent regioselectivities, which are much better than those reported in literature. With 1,2-disubstituted unactivated alkenes, the reaction is largely stereospecific. The cyclobutene products can be prepared in nearly gram scale and readily undergo further reactions including various cross-coupling reactions using the C(sp2)-Cl and/or C(sp2)-SPh bond, which in turn substantially broaden the scope of accessible cyclobutenes and enhance the synthetic utility of this bimolecular reaction.
- Bai, Yu-Bin,Luo, Zaigang,Wang, Yuguang,Gao, Jin-Ming,Zhang, Liming
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p. 5860 - 5865
(2018/05/14)
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- Trimethylsilyl-Protected Alkynes as Selective Cross-Coupling Partners in Titanium-Catalyzed [2+2+1] Pyrrole Synthesis
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Trimethylsilyl (TMS)-protected alkynes served as selective alkyne cross-coupling partners in titanium-catalyzed [2+2+1] pyrrole synthesis. Reactions of TMS-protected alkynes with internal alkynes and azobenzene under the catalysis of titanium imido comple
- Chiu, Hsin-Chun,Tonks, Ian A.
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p. 6090 - 6094
(2018/05/30)
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- Compartmentalized host spaces accommodating guest aromatic molecules in a chiral way in a helix-peptide-aromatic framework
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A novel host molecular assembly of a free-standing flat nanosheet with compartmentalized spaces was prepared using a bolaamphiphilic peptide composed of two amphiphilic helical peptides and an oligo(naphthaleneethynylene) (ONE) unit at the center of the m
- Uji, Hirotaka,Ogawa, Junya,Itabashi, Kenji,Imai, Tomoya,Kimura, Shunsaku
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p. 12483 - 12486
(2018/11/23)
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- An NNN-Pincer-Cobalt Complex Catalyzed Highly Markovnikov-Selective Alkyne Hydrosilylation
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A new NNN pincer (amine-pyridine-imine, API) cobalt complex, which is bench-stable and is applicable for the highly efficient and regioselective hydrosilylation of terminal alkynes, is developed. A broad set of α-vinylsilanes was successfully synthesized in good to high yields with up to 98/2 Markovnikov regioselectivity. This protocol can be readily scaled up for gram-scale synthesis and demonstrates the most efficient cobalt-catalyzed hydrosilylation of alkynes with turnover frequencies as high as 126720 h-1 to date.
- Ibrahim, Jessica Juweriah,Yang, Yong,Zhang, Shaochun
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- Palladium-catalyzed tandem C-H functionalization/cyclization strategy for the synthesis of 5-hydroxybenzofuran derivatives
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A palladium-catalyzed benzoquinone C-H functionalization/ cyclization strategy with terminal alkynes was employed for the synthesis of some biologically relevant 2, 3-disubstituted 5-hydroxybenzofuran derivatives. The benzoquinone acts as a reactant as well as an oxidant. During the process, an additional alkyne functionality can be introduced at the C3 position of the benzofuran. Base, ligand, and external oxidant are not required in this protocol.
- Ichake, Sachin S.,Konala, Ashok,Kavala, Veerababurao,Kuo, Chun-Wei,Yao, Ching-Fa
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supporting information
p. 54 - 57
(2017/11/28)
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- Efficient Microwave-Assisted Synthesis of Sonogashira-Coupled Perylene Monoimide Derivatives: Impact of Electron-Donating Groups on Optoelectronic Properties
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An efficient microwave-assisted Sonogashira-coupling protocol for the synthesis of peri-functionalized perylene monoimide dye derivatives was developed. This method was found to be significantly faster than the conventional coupling method and provided pr
- Sharma, Vikas,Chandra, Falguni,Sahoo, Dhananjaya,Koner, Apurba L.
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supporting information
p. 6901 - 6905
(2017/12/26)
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- Products of the Propargyl Self-Reaction at High Temperatures Investigated by IR/UV Ion Dip Spectroscopy
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The propargyl radical is considered to be of key importance in the formation of the first aromatic ring in combustion processes. Here we study the bimolecular (self-) reactions of propargyl in a high-temperature pyrolysis flow reactor. The aromatic reaction products are identified by IR/UV ion dip spectroscopy, using the free electron laser FELIX as mid-infrared source. This technique combines mass selectivity with structural sensitivity. We identified several aromatic reaction products based on their infrared spectra, among them benzene, naphthalene, phenanthrene, indene, biphenyl, and surprisingly a number of aromatic compounds with acetylenic (ethynyl) side chains. The observation of benzene confirms that propargyl is involved in the formation of the first aromatic ring. The observation of compounds with acetylenic side chains shows that, in addition to a propargyl- and phenyl-based mechanism, the HACA (hydrogen abstraction C2H2 addition) mechanism of polycyclic aromatic hydrocarbons formation is present, although no acetylene was used as a reactant. On the basis of the experimental results we suggest a mechanism that connects the two pathways.
- Constantinidis,Hirsch,Fischer,Dey,Rijs
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p. 181 - 191
(2017/06/07)
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- New cyclometalated iridium(III) dye chromophore complexes for n-type dye-sensitised solar cells
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The synthesis of seven iridium complexes where aryl-1,2,3-triazole (Ar-tz) moieties act as cyclometalating ligands with 2,2′-bipyridyl-4,4′-dicarboxylic acid (dcb) as a N^N ancillary/anchoring ligand, is described. The new dye complexes [Ir(Ar-tz)2(dcb)][PF6] (AS1-7) were prepared in a two stage procedure with iridium-chloride dimer isolation. DFT analysis together with photophysical investigations reveal how using different substituents on the phenyl ring, or a different aryl system, lead to the tuning of the absorption and emission properties of these complexes. Computational studies therefore demonstrate an ideal HOMO-LUMO directionality for the [Ir(Ar-tz)2(dcb)]+framework, promoting a favourable electron transfer into the TiO2conduction band upon photoexcitation. Preliminary unoptimized tests on TiO2DSSCs have been carried out which show similar photovoltaic performance to the [Ir(ppy)2(dcb)][PF6] (ppy = 2-phenylpyridine) benchmark.
- Sinopoli, Alessandro,Wood, Christopher J.,Gibson, Elizabeth A.,Elliott, Paul I.P.
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supporting information
p. 81 - 89
(2016/12/26)
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- Discovery of a novel series of N-hydroxypyridone derivatives protecting astrocytes against hydrogen peroxide-induced toxicity via improved mitochondrial functionality
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Astrocytes play a key role in brain homeostasis, protecting neurons against neurotoxic stimuli such as oxidative stress. Therefore, the neuroprotective therapeutics that enhance astrocytic functionality has been regarded as a promising strategy to reduce brain damage. We previously reported that ciclopirox, a well-known antifungal N-hydroxypyridone compound, protects astrocytes from oxidative stress by enhancing mitochondrial function. Using the N-hydroxypyridone scaffold, we have synthesized a series of cytoprotective derivatives. Mitochondrial activity assay showed that N-hydroxypyridone derivatives with biphenyl group have comparable to better protective effects than ciclopirox in astrocytes exposed to H2O2. N-hydroxypyridone derivatives, especially 11g, inhibited H2O2-induced deterioration of mitochondrial membrane potential and oxygen consumption rate, and significantly improved cell viability of astrocytes. The results indicate that the N-hydroxypyridone motif can provide a novel cytoprotective scaffold for astrocytes via enhancing mitochondrial functionality.
- Singh, Sarbjit,Goo, Ja-Il,Noh, Hyojin,Lee, Sung Jae,Kim, Myoung Woo,Park, Hyejun,Jalani, Hitesh B.,Lee, Kyeong,Kim, Chunsook,Kim, Won-Ki,Ju, Chung,Choi, Yongseok
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p. 1394 - 1405
(2017/02/18)
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- Heterocyclic compounds, comprising of organic light-emitting device and organic light emitting display
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Heterocyclic compounds, synthetic methods for preparing the same, and organic light-emitting display devices comprising the same are described. The subject heterocyclic compounds may comprise an aromatic ring or a heteroaromatic ring fused with a carbazole, dibenzothiophene, or dibenzofurane derivative, the compounds featuring rigid backbone structures with high glass transition temperatures and high melting points. The subject heterocyclic compounds may exhibit high electrical stability, improved charge transport ability, high heat resistance and improved light-emitting properties when used in organic light-emitting devices. Organic light-emitting display devices prepared according to the present invention exhibit lower driving voltages, increased luminescent efficiencies and longer lifetimes.
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Paragraph 0300; 0324-0328
(2017/09/13)
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- Domino Hydroboration/Trifluoromethylation of Alkynes Using Fluoroform-Derived [CuCF3]
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A domino hydroboration/trifluoromethylation (formal hydrotrifluoromethylation) of alkynes using the fluoroform-derived [CuCF3] reagent is achieved. Synthetically useful (E)-alkenyl-CF3 building blocks and 1,1-bis(trifluoromethyl)-substituted alkenes can be prepared under ambient conditions in one pot/one step from alkynes. The ultimate source of CF3 is the inexpensive industrial waste fluoroform.
- He, Lisi,Yang, Xinkan,Tsui, Gavin Chit
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p. 6192 - 6201
(2017/06/23)
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- Synthesis and cytotoxicity evaluation of aryl triazolic derivatives and their hydroxymethine homologues against B16 melanoma cell line
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In this manuscript we describe synthesis and cytotoxicity evaluation of some triazolic derivatives against B16 melanoma cell line. For this purpose, we transformed a set of aromatic aldehydes into terminal alkynes, using Besthmann-Ohira reagent, and we made the corresponding hydroxymethyl homologated alkynes by an acetylene Grignard reagent. These generated two sets of alkynes were then subjected to a copper(I)-catalyzed alkyne-azide cycloaddition reaction (CuAAC) using a solid-supported catalyst (Amberlyst A-21?CuI), with a third set composed of organic azides. Synthesized triazoles were then tested in?vitro against B16 melanoma cell line. Amongst them, compounds a1b1 (R1?=?p-nitrophenyl, R2?=?benzyl), a4b1 (R1?=?naphthyl, R2?=?benzyl) and a4b5 (R1?=?naphthyl, R2?=?(R/S)- dioxolane) showed the best activity against B16 melanoma cells, with IC50of 5.12, 3.89 and 6.60?μM respectively.
- Kalhor-Monfared, Shiva,Beauvineau, Claire,Scherman, Daniel,Girard, Christian
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supporting information
p. 436 - 441
(2016/07/15)
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- Rapid access to unsymmetrical tolanes and alkynones by sequentially palladium-catalyzed one-pot processes
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Alkynones as well as unsymmetrically substituted tolanes (diarylalkynes) can be rapidly generated in a one-pot fashion via sequential palladium catalysis. Terminal alkynes, formed in situ by protecting-group free palladium-catalyzed coupling of aryl iodides with ethynyl magnesium bromide, are subsequently transformed by Sonogashira coupling with aryl halides or aroyl chlorides to furnish unsymmetrically substituted alkynes in good to excellent yields.
- G?tzinger, Alissa C.,Müller, Thomas. J. J.
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supporting information
p. 3498 - 3500
(2016/04/19)
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- Synthesis of Barbaralones and Bullvalenes Made Easy by Gold Catalysis
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The gold(I)-catalyzed oxidative cyclization of 7-ethynyl-1,3,5-cycloheptatrienes gives 1-substituted barbaralones in a general manner, which simplifies the access to other fluxional molecules. As an example, we report the shortest syntheses of bullvalene, phenylbullvalene, and disubstituted bullvalenes, and a readily accessible route to complex cage-type structures by further gold(I)-catalyzed reactions.
- Ferrer, Sofia,Echavarren, Antonio M.
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p. 11178 - 11182
(2016/10/13)
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- Deazapurine methylnucleoside derivative, and polynucleotide deriv. [...] deriv.
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PROBLEM TO BE SOLVED: To provide a new fluorescent nucleic acid in which the fluorescence emission wavelength changes due to difference of a surrounding polar environment and which does not destabilize the double-helix structure of DNA even when introduce
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- 2-Aryl-8-aza-3-deazaadenosine analogues of 5′-O-[N-(salicyl)sulfamoyl]adenosine: Nucleoside antibiotics that block siderophore biosynthesis in Mycobacterium tuberculosis
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A series of 5′-O-[N-(salicyl)sulfamoyl]-2-aryl-8-aza-3-deazaadenosines were designed to block mycobactin biosynthesis in Mycobacterium tuberculosis (Mtb) through inhibition of the essential adenylating enzyme MbtA. The synthesis of the 2-aryl-8-aza-3-deaz
- Krajczyk, Anna,Zeidler, Joanna,Januszczyk, Piotr,Dawadi, Surendra,Boshoff, Helena I.,Barry, Clifton E.,Ostrowski, Tomasz,Aldrich, Courtney C.
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supporting information
p. 3133 - 3143
(2016/07/06)
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- Manganese-Catalyzed ortho-C?H Alkenylation of Aromatic N?H Imidates with Alkynes: Versatile Access to Mono-Alkenylated Aromatic Nitriles
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So far, the direct C?H alkenylation of aromatic nitriles with alkynes has not been achieved. Herein, we discribe the first manganese-catalyzed C?H alkenylation of aromatic N?H imidates to access mono-alkenylated aromatic nitriles. The reaction is accelerated by the presence of a catalytic amount of sodium pivalate. This protocol is also highlighted by the simple catalytic system, good compatibility of functional groups, and excellent mono-/dialkenylation selectivity as well as E/Z stereoselectivity. (Figure presented.).
- Yang, Xiaoxu,Jin, Xiqing,Wang, Congyang
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supporting information
p. 2436 - 2442
(2016/08/16)
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- Visible-Light-Promoted Vinylation of Tetrahydrofuran with Alkynes through Direct C-H Bond Functionalization
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(Chemical Equation Presented) Mild and direct C-H bond functionalizations and vinylations of tetrahydrofuran with alkynes have been accomplished through visible light photocatalysis, yielding a range of vinyl tetrahydrofurans under the synergistic actions of organic dye-type photocatalyst eosin Y, tert-butyl hydroperoxide (t-BuOOH), and a 45 W household lightbulb. A significant kinetic isotope effect (KIE) was recorded, which helps shed light on the mechanistic course.
- Li, Jing,Zhang, Jing,Tan, Haibo,Wang, David Zhigang
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p. 2522 - 2525
(2015/05/27)
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- A practical, chemoselective approach to O-methylation of carboxylic acids with dimethyl malonate
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A practical and chemoselective method is described for the O-methylation of carboxylic acids. Dimethyl malonate, a low toxic and commercially available compound was found to be an effective methylating reagent for a variety of carboxylic acids affording methyl ester products in good to high yields and with excellent chemoselectivity, without the use of strong bases as additives. A mechanism involving the utilization of potassium bromide is tentatively proposed.
- Mao, Jincheng,Liu, Defu,Li, Yongming,Zhao, Jinzhou,Rong, Guangwei,Yan, Hong,Zhang, Guoqi
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p. 9067 - 9072
(2015/11/09)
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- Falling-solid flash vacuum pyrolysis: An efficient preparation of arylacetylenes
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Automated falling-solid flash vacuum pyrolysis allows the rapid and efficient synthesis of a variety of arylacetylenes from 4-arylmethylidene-5(4H)-isoxazolone derivatives, which were prepared from aldehyde precursors. The acetylenes are readily obtained in multigram quantities. Taking the heat: Unlike in flash vacuum pyrolysis, involatile compounds can be used in falling-solid flash vacuum pyrolysis (FS-FVP). This method is employed for the rapid and efficient synthesis of a variety of arylacetylenes from 4-arylmethylidene-5(4H)-isoxazolones, which were in turn prepared from aldehyde precursors.
- Wentrup, Curt,Becker, Jürgen,Winter, Hans-Wilhelm
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supporting information
p. 5702 - 5704
(2015/09/21)
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- Synthesis of alkynes from vinyl triflates using tetrabutylammonium fluoride
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A convenient method for the preparation of alkynes and alkynyl esters from ketones and β-keto esters is described which involves the formation of vinyl triflates, followed by elimination with tetrabutylammonium fluoride trihydrate, to give alkynes. Unlike established elimination methods, the method requires neither a strong base nor anhydrous conditions.
- Okutani, Masaru,Mori, Yuji
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p. 393 - 396
(2015/06/17)
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- Assembly of organosilver coordination frameworks with polycyclic benzenoid aromatic ethynide ligands
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Abstract In a series of nine silver(I) complexes synthesized with ethynyl-functionalized condensed-ring benzenoid aromatics, the terminal ethynide group is invariably inserted into an argentophilic Agn (n = 4-5) basket, leading to the generation of coordination chains or multinuclear metallocycles via silver-aromatic interaction and strong face-to-face aromatic π-π stacking interaction. The coordination preferences of the ethynide ligand with respect to the size of the aromatic nucleus proved to be dominant factors in directing the construction of multi-dimensional organosilver(I) networks, which are consolidated by weak intermolecular interactions in supramolecular assembly.
- Hau, Sam C.K.,Mak, Thomas C.W.
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p. 123 - 133
(2015/08/18)
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- Sodium sulfide in methanol: A two-in-one reagent for deprotection of silyl and formation of propargyl sulfide
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A new reagent Na2S/MeOH for silyl deprotection has been developed. The reagent has several advantages which include deprotection of C-TMS, O-TMS, O-TBS, and O-TBDPS, selective removal of C-TMS and O-TMS in the presence of O-TBS and simultaneous
- Hatial, Ishita,Mukherjee, Raja,Senapati, Kalyan,Basak, Amit
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supporting information
p. 4275 - 4279
(2015/06/22)
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- Mn-catalyzed aromatic C-H alkenylation with terminal alkynes
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The first manganese-catalyzed aromatic C-H alkenylation with terminal alkynes is described. The procedure features an operationally simple catalyst system containing commercially available MnBr(CO)5 and dicyclohexylamine (Cy2NH). The reaction occurs readily in a highly chemo-, regio-, and stereoselective manner delivering anti-Markovnikov E-configured olefins in high yields. Experimental study and DFT calculations reveal that (1) the reaction is initiated by a C-H activation step via the cooperation of manganese and base; (2) manganacycle and alkynylmanganese species are the key reaction intermediates; and (3) the ligand-to-ligand H-transfer and alkynyl-assisted C-H activation are the key steps rendering the reaction catalytic in manganese.
- Zhou, Bingwei,Chen, Hui,Wang, Congyang
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p. 1264 - 1267
(2013/03/14)
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- Emission and transient absorption measurements of substitution effects of C-C triple bonds on relaxation processes of the fluorescent state of naphthalenes
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Photophysical and photochemical properties of naphthalenes substituted with trimethylsilylethynyl, tert-butylethynyl, and trimethylsilylbutadiynyl groups were investigated by measurement of fluorescence yields, lifetimes, and triplet absorption. Introducing trimethylsilylethynyl and tert-butylethynyl groups to the 1-position of the naphthalene skeleton substantially enhanced fluorescence and intersystem crossing (ISC). The rates of fluorescence of 2-substituted naphthalenes were low. The effect of ethynyl groups on the 1-substituted naphthalenes was rationalized in terms of an increase of the transition moment along the short axis of the naphthalene skeleton. Substitution of the trimethylsilylbutadiynyl group at the 1 or 2-position of the naphthalene skeleton caused a considerable decrease in the fluorescence yield (approximately 0.01) and an increase in the ISC yield (0.99).
- Yamaji, Minoru,Maeda, Hajime,Minamida, Keita,Maeda, Tomohiro,Asai, Kengo,Konishi, Gen-Ichi,Mizuno, Kazuhiko
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p. 321 - 345
(2013/03/14)
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- Unique solvent-dependent fluorescence of nitro-group-containing naphthalene derivatives with weak donor-strong acceptor system
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We synthesized nitro-group-containing π-conjugated naphthalene derivatives with a weak donor-strong acceptor system and investigated their photophysical properties. The nitro group was introduced into naphthalene through the phenyl or phenylethynyl moiety at the C2 and C7 positions as the strong acceptor moiety, and a methoxy group was introduced into naphthalene directly at the position opposite to the nitro group, as a weak donor moiety. While 2-(4-nitrophenyl)naphthalene did not show fluorescence in various solvents, 2-methoxy-6-(4-nitrophenyl)naphthalene showed fluorescence in weakly polar solvents (ΦF = 0.11 in CH2Cl2), with a large Stokes shift (Δν = 12,000 cm-1). Additionally, 2-methoxy-6-(4-nitrophenyl)naphthalene did not show fluorescence in polar solvents (acetonitrile) and non-polar solvents (toluene). This unique solvent-dependent fluorescence is remarkable for environmental fluorescence sensor applications.
- Hachiya, Sojiro,Asai, Kengo,Konishi, Gen-Ichi
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p. 1839 - 1841
(2013/05/09)
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- Gold-catalyzed oxazoles synthesis and their relevant antiproliferative activities
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Nine 5-aryl-2-methyloxazole derivatives were synthesized via gold-catalyzed alkyne oxidation. All of the compounds have been screened for their antiproliferative activities against MCF-7 cell (human breast carcinoma), A549 cell (human lung carcinoma) and
- Wu, Chao,Liang, Zhi-Wu,Xu, Ying-Ying,He, Wei-Min,Xiang, Jian-Nan
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p. 1064 - 1066
(2014/01/06)
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- Regioselective solvent-dependent benzannulation of conjugated enynes
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The transformation of enynes under cobalt-catalysis leads to symmetrical benzannulation products in dichloromethane. In tetrahydrofuran the cobalt-catalysed reactions afforded the unprecedented unsymmetrical benzannulation products in moderate to good yields and good regioselectivities. In addition, cyclotrimerisation of the alkyne subunit can be realised when electron-deficient enynes are applied in the cobalt-catalysed transformations to generate 1,2,4-trivinylbenzene derivatives using tetrahydrofuran as solvent.
- Puenner, Florian,Hilt, Gerhard
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p. 3617 - 3619
(2012/05/20)
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- Synthesis of 3-alkyl enol mimics inhibitors of type II dehydroquinase: Factors influencing their inhibition potency
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Several 3-alkylaryl mimics of the enol intermediate in the reaction catalyzed by type II dehydroquinase were synthesized to investigate the effect on the inhibition potency of replacing the oxygen atom in the side chain by a carbon atom. The length and the rigidity of the spacer was also studied. The inhibitory properties of the reported compounds against type II dehydroquinase from Mycobacterium tuberculosis and Helicobacter pylori are also reported. The binding modes of these analogs in the active site of both enzymes were studied by molecular docking using GOLD 5.0 and dynamic simulations studies.
- Blanco, Beatriz,Sedes, Anti,Peon,Lamb, Heather,Hawkins, Alastair R.,Castedo, Luis,Gonzalez-Bello, Concepcion
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experimental part
p. 3662 - 3676
(2012/06/01)
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- A concise route to dihydrobenzo[b]furans: Formal total synthesis of (+)-lithospermic acid
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A sequence of Sonogashira coupling, Pd(II)-catalyzed carbonylative annulation, and benzofuran reduction (Mg, MeOH, NH4Cl) provides a convergent and modular synthetic route to trans-2-aryl-2,3-dihydrobenzo[b]furan- 3-carboxylates, which are a structural feature of numerous biologically active natural products. This versatile strategy was applied to the formal total synthesis of the anti-HIV natural product (+)-lithospermic acid.
- Fischer, Joshua,Savage, G. Paul,Coster, Mark J.
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supporting information; body text
p. 3376 - 3379
(2011/09/12)
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