- 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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supporting information
p. 515 - 526
(2022/01/08)
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- Biphenyl Cyclobutenone Photoelectrocyclizations
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In this work, we demonstrate that readily available conjugated bis-aryl cyclobutenones undergo photoelectrocyclization reactions to give the corresponding dihydrophenanthrene cyclobutanones when exposed to 350 nm light, TFA, and TMSCl. We have also found that cyclobutenone electrocyclizations and cycloreversions are in equilibrium.
- Dai, Changhang,Rainier, Jon D.,Schwartz, Zach,Song, Changqing,Zhao, Xuchen
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p. 15164 - 15176
(2021/10/20)
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- Metal-Free Synthesis of Selenodihydronaphthalenes by Selenoxide-Mediated Electrophilic Cyclization of Alkynes
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A transition-metal-free, selenium mediated electrophilic cyclization reaction was realized through a one-pot procedure between simple alkynes and triflic anhydride-activated selenoxides to give selenium containing dihydronaphthalene products. This method gave good to very high yields for all products, including selenium-substituted phenanthrene, dihydroquinoline, 2H-chromene, and coumarin, which can be further transformed to other functionalized compounds.
- An, Shaoyu,Li, Pingfan,Zhang, Zhong
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p. 3059 - 3070
(2021/07/22)
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- Iodine-Catalyzed Methylthiolative Annulation of 2-Alkynyl Biaryls with DMSO: A Metal-Free Approach to 9-Sulfenylphenanthrenes
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An iodine-catalyzed sustainable, cost-effective, and atom-economic synthetic methodology is developed to synthesize a wide variety of valuable sulfenylphenanthrenes and polycyclic heteroaromatics in moderate to high yield through electrophilic thiolative annulation of 2-alkynyl biaryls (6-endo-dig cyclization) using methyl sulfoxides such as dimethyl sulfoxide (DMSO) as the sulfur source under transition-metal-free conditions. The transformation requires only iodine in a catalytic amount and trifluoroacetic anhydride. Notably, DMSO played multiple roles such as methylthiolating reagent, oxidant, and solvent in this reaction.
- Chatterjee, Tanmay,Mukherjee, Nilanjana
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p. 7881 - 7890
(2021/06/28)
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- Gold-Catalyzed Synthesis of π-Extended Carbazole-Based Systems and their Application as Organic Semiconductors
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Herein we describe a gold-catalyzed bidirectional synthesis of N-heteropolycyclic compounds bearing carbazole moieties – namely π-extended benzodicarbazoles and π-extended indolocarbazoles. Overall, four previously unknown core structures were synthesized. This approach is convergent, modular and the gold-catalyzed key step comprises of a cascade reaction starting from stable di-azido compounds. The obtained molecules were fully characterized and their optical and electronic properties as well as their performance in organic thin-film transistors generated by vacuum deposition were studied. Charge-carrier mobilities of up to 0.3 cm2/Vs were measured. (Figure presented.).
- Hendrich, Christoph M.,Hannibal, Valentin D.,Eberle, Lukas,Hertwig, Leif E.,Zschieschang, Ute,Rominger, Frank,Rudolph, Matthias,Klauk, Hagen,K. Hashmi, A. Stephen
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p. 1401 - 1407
(2021/02/03)
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- Synthesis and Photochemical Application of Hydrofluoroolefin (HFO) Based Fluoroalkyl Building Block
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A novel fluoroalkyl iodide was synthesized on multigram scale from refrigerant gas HFO-1234yf as cheap industrial starting material in a simple, solvent-free, and easily scalable process. We demonstrated its applicability in a metal-free photocatalytic ATRA reaction to synthesize valuable fluoroalkylated vinyl iodides and proved the straightforward transformability of the products in cross-coupling chemistry to obtain conjugated systems.
- Varga, Bálint,Tóth, Balázs L.,Béke, Ferenc,Csenki, János T.,Kotschy, András,Novák, Zoltán
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p. 4925 - 4929
(2021/07/01)
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- Alumina-Mediated π-Activation of Alkynes
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The ability to induce powerful atom-economic transformation of alkynes is the key feature of carbophilic π-Lewis acids such as gold- and platinum-based catalysts. The unique catalytic activity of these compounds in electrophilic activations of alkynes is explained through relativistic effects, enabling efficient orbital overlapping with π-systems. For this reason, it is believed that noble metals are indispensable components in the catalysis of such reactions. In this study, we report that thermally activated γ-Al2O3activates enynes, diynes, and arene-ynes in a manner enabling reactions that were typically assigned to the softest π-Lewis acids, while some were known to be triggered exclusively by gold catalysts. We demonstrate the scope of these transformations and suggest a qualitative explanation of this phenomenon based on the Dewar-Chatt-Duncanson model confirmed by density functional theory calculations.
- Akhmetov, Vladimir,Amsharov, Konstantin,Feofanov, Mikhail,Sharapa, Dmitry I.
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p. 15420 - 15426
(2021/09/30)
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- Palladium-catalyzed denitrative Sonogashira-type cross-coupling of nitrobenzenes with terminal alkynes
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Described herein is a palladium-catalyzed cross-coupling reaction between nitroarenes and terminal alkynes, offering a facile method for C(sp2)-C(sp) bond formation. The utility of this protocol has been proven by the construction of polycyclic aromatic hydrocarbons (PAHs) and orthogonal cross-coupling.
- Feng, Boya,Yang, Yudong,You, Jingsong
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supporting information
p. 790 - 793
(2020/01/29)
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- Electrophilic Cyanative Alkenylation of Arenes
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A variety of appropriately substituted internal alkynes were transformed into the corresponding cyano-substituted phenanthrenes, dihydronaphthalenes, and cyclohepta-1,3,5-trienes in moderate to excellent yields by treatment with imidazolium thiocyanate 1, which serves as an easy to handle [CN]+ precursor, in the presence of BCl3. The synthetic value of the method is additionally demonstrated by the transformation of the primarily obtained products into heavily substituted quinolines. Additionally, the dynamic properties of the prepared dibenzocyclohepta-1,3,5-trienes have been investigated.
- Zhao, Mingyue,Barrado, Alejandro G.,Sprenger, Kristin,Golz, Christopher,Mata, Ricardo A.,Alcarazo, Manuel
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supporting information
p. 4932 - 4937
(2020/06/08)
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- Br?nsted Acid-Catalyzed Enantioselective Cycloisomerization of Arylalkynes
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The first example of an enantioselective carbocyclization of an alkyne-containing substrate catalyzed by chiral Br?nsted acids was achieved. The use of the 2-hydroxynaphthyl substituent on the alkyne as a directing group constituted the key parameter enabling both efficient regioselective protonation of the carbon–carbon triple bond and chiral induction. The key cationic intermediate could be depicted either as a cationic vinylidene ortho-quinone methide or a stabilized vinyl cation. Atropoisomeric phenanthrenes derivatives were produced in high yields and good enantioselectivities under mild, metal-free reaction conditions in the presence of chiral N-triflylphosphoramide catalysts. The carbenic nature of the cationic intermediate was also exploited to describe an example of alkyne/alkane cycloisomerization.
- Abadie, Baptiste,Berlande, Murielle,Dhara, Kalyan,Gicquiaud, Julien,Hermange, Philippe,Sotiropoulos, Jean-Marc,Toullec, Patrick Y.
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p. 16266 - 16271
(2020/11/30)
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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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- SILICON-CONTAINING ELECTRON TRANSPORTING MATERIAL AND ITS APPLICATION
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A silicon-containing electron transporting material and its application are disclosed. The silicon-containing electron transporting material employs a silicon-containing compound with a novel structure containing one or more silicon atoms and a specific g
- -
-
Paragraph 0123; 0125; 0129-0130; 0140; 0143-0144
(2020/05/14)
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- Cobaloxime Catalysis: selective synthesis of alkenylphosphine oxides under visible light
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Direct activation of H-phosphine oxide to react with an unsaturated carbon-carbon bond is a straightforward approach for accessing alkenylphosphine oxides, which shows significant applications in both synthetic and material fields. However, expensive metals and strong oxidants are typically required to realize the transformation. Here, we demonstrate the utility of earth-abundant cobaloxime to convert H-phosphine oxide into its reactive radical species under visible light irradiation. The radical species thus generated can be utilized to functionalize alkenes and alkynes without any external photosensitizer and oxidant. The coupling with terminal alkene generates E-alkenylphosphine oxide with excellent chemo- A nd stereoselectivity. The reaction with terminal alkyne yields linear E-alkenylphosphine oxide via neutral radical addition, while addition with internal ones generates cyclic benzophosphine oxides and hydrogen. Mechanistic studies on radical trapping experiments, electron spin resonance studies, and spectroscopic measurements confirm the formation of phosphinoyl radical and cobalt intermediates that are from capturing the electron and proton eliminated from H-phosphine oxide. The highlight of our mechanistic investigation is the dual role played by cobaloxime, viz., both as the visible light absorber to activate the P(O)-H bond as well as a hydrogen transfer agent to influence the reaction pathway. This synergetic feature of the cobaloxime catalyst preforming multiple functions under ambient condition provides a convergent synthetic approach to vinylphosphine oxides directly from H-phosphine oxides and alkenes (or alkynes).
- Liu, Wen-Qiang,Lei, Tao,Zhou, Shuai,Yang, Xiu-Long,Li, Jian,Chen, Bin,Sivaguru, Jayaraman,Tung, Chen-Ho,Wu, Li-Zhu
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supporting information
p. 13941 - 13947
(2019/09/30)
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- Cobaloxime Catalysis: Selective Synthesis of Alkenylphosphine Oxides under Visible Light
-
Direct activation of H-phosphine oxide to react with an unsaturated carbon-carbon bond is a straightforward approach for accessing alkenylphosphine oxides, which shows significant applications in both synthetic and material fields. However, expensive metals and strong oxidants are typically required to realize the transformation. Here, we demonstrate the utility of earth-abundant cobaloxime to convert H-phosphine oxide into its reactive radical species under visible light irradiation. The radical species thus generated can be utilized to functionalize alkenes and alkynes without any external photosensitizer and oxidant. The coupling with terminal alkene generates E-alkenylphosphine oxide with excellent chemo- and stereoselectivity. The reaction with terminal alkyne yields linear E-alkenylphosphine oxide via neutral radical addition, while addition with internal ones generates cyclic benzophosphine oxides and hydrogen. Mechanistic studies on radical trapping experiments, electron spin resonance studies, and spectroscopic measurements confirm the formation of phosphinoyl radical and cobalt intermediates that are from capturing the electron and proton eliminated from H-phosphine oxide. The highlight of our mechanistic investigation is the dual role played by cobaloxime, viz., both as the visible light absorber to activate the P(O)-H bond as well as a hydrogen transfer agent to influence the reaction pathway. This synergetic feature of the cobaloxime catalyst preforming multiple functions under ambient condition provides a convergent synthetic approach to vinylphosphine oxides directly from H-phosphine oxides and alkenes (or alkynes).
- Liu, Wen-Qiang,Lei, Tao,Zhou, Shuai,Yang, Xiu-Long,Li, Jian,Chen, Bin,Sivaguru, Jayaraman,Tung, Chen-Ho,Wu, Li-Zhu
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supporting information
p. 13941 - 13947
(2019/09/30)
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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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- 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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supporting information
p. 1461 - 1464
(2018/03/08)
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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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- Silver-Catalyzed Tandem C=C Bond Hydroazidation/Radical Addition/Cyclization of Biphenyl Acetylene: One-Pot Synthesis of 6-Methyl Sulfonylated Phenanthridines
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A silver-catalyzed tandem carbon-carbon triple bond hydroazidation, radical addition, and cyclization of biphenyl acetylene is described under mild conditions, leading to the formation of 6-methyl sulfonylated phenanthridines in good yields. In this novel cascade reaction, most of the atoms are incorporated into the product without cleavage of the C=C bond. Mechanistic studies suggest the reaction should proceed through an iminyl radical reactive intermediate.
- Tang, Jiawei,Sivaguru, Paramasivam,Ning, Yongquan,Zanoni, Giuseppe,Bi, Xihe
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supporting information
p. 4026 - 4029
(2017/08/14)
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- Gold-Catalyzed Oxidation Terminal Alkyne: An Approach to Synthesize Substituted Dihydronaphthalen-2(1H)-ones and Phenanthrenols
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A facile gold-catalyzed oxidation terminal alkynes to synthesize substituted dihydronaphthalen-2(1H)-ones 3 and phenanthrenols 5 was realized. Various useful structures and drug precursors were generated in up to 99% yield under mild condition and low catalyst loading.
- Ling, Hui-Bo,Chen, Zi-Sheng,Yang, Fang,Xu, Bin,Gao, Jin-Ming,Ji, Kegong
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p. 7070 - 7076
(2017/07/15)
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- Palladium-Catalyzed Synthesis of Tetrasubstituted Olefins by Triple Domino Process
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An efficient, highly regio- and stereoselective protocol for the synthesis of tetrasubstituted olefins was developed to take place by a palladium(0)-catalyzed triple domino process. It involves the formation of three new C?C bonds through double carbopalladation and C?H activation across 2-bromoaryl alkynyl biaryls/heteroaryls with norbornene. This method is practically simple with broad substrate scope and tolerates a wide range of substituents. The products bearing 9H-pyrrolo[1,2-a]indole motifs reveal intriguing solid state fluorescence properties and thus form a new class of aggregation induced emission (AIE) fluorophores. (Figure presented.).
- Naveen, Kanagaraj,Nikson, Savariyappan Albert,Perumal, Paramasivan Thirumalai
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p. 2407 - 2413
(2017/07/22)
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- Palladium-Catalyzed Cascade Arene/Alkyne Annulation: Synthesis of Fluorene-Benzoxazine Derivatives
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A palladium-catalyzed cascade arene/alkyne annulation reaction for the synthesis of fluorene-benzoxazine derivatives is developed. This transformation involves a 6-exo-dig cyclization, a 1,3-oxazine vinylpalladium intermediate, and a C-H bond activation.
- Cai, Zhong-Jian,Li, Fang-Hui,Wang, Shun-Yi,Ji, Shun-Jun
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supporting information
p. 4810 - 4813
(2016/10/14)
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- Copper-catalyzed cascade annulation between α-bromocarbonyls and biaryl or (: Z)-arylvinylacetylenes enabling a direct synthesis of dibenzocycloheptanes and related compounds
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Copper-catalyzed cascade annulation of γ,δ-unsaturated α-bromocarbonyls with biaryl or (Z)-arylvinylacetylenes is presented, giving an expeditious access to dibenzocycloheptanes and related compounds in moderate to high yields. It provides a novel method for the one-pot synthesis of cycloheptane and cycloheptene-fused polycyclic scaffolds featuring a rare 7-endo-trig radical cyclization.
- Lu, Danyang,Wan, Yimei,Kong, Lichun,Zhu, Gangguo
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supporting information
p. 13971 - 13974
(2016/12/09)
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- Alkynes as Linchpins for the Additive Annulation of Biphenyls: Convergent Construction of Functionalized Fused Helicenes
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A new approach to fused helicenes is reported, where varied substituents are readily incorporated in the extended aromatic frame. From the alkynyl precursor, the final helical compounds are obtained under mild conditions in a two-step process, in which th
- Mohamed, Rana K.,Mondal, Sayantan,Guerrera, Joseph V.,Eaton, Teresa M.,Albrecht-Schmitt, Thomas E.,Shatruk, Michael,Alabugin, Igor V.
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p. 12054 - 12058
(2016/11/16)
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- Synthesis of Functionalized Phenanthrenes via Regioselective Oxidative Radical Cyclization
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The majority of Sn-mediated cyclizations are reductive and, thus, cannot give a fully conjugated product. This is a limitation in the application of Sn-mediated radical cascades for the preparation of fully conjugated molecules. In this work, we report an oxidatively terminated Bu3Sn-mediated cyclization of an alkyne where AIBN, the commonly used initiator, takes on a new function as an oxidative agent. Sn-mediated radical transformation of biphenyl aryl acetylenes into functionalized phenanthrenyl stannanes can be initiated via two potentially equilibrating vinyl radicals, one of which can be trapped by the fast 6-endoclosure at the biphenyl moiety in good to excellent yields. The efficient preparation of Sn-substituted phenanthrenes opens access to convenient building blocks for the construction of larger polyaromatics.
- Pati, Kamalkishore,Michas, Christopher,Allenger, David,Piskun, Ilya,Coutros, Peter S.,Dos Passos Gomes, Gabriel,Alabugin, Igor V.
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p. 11706 - 11717
(2015/12/11)
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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 4-alkylidene-substituted 1,2,3,4-tetrahydroisoquinolines via palladium-catalyzed carbopalladation/C-H activation of 2-bromobenzyl-N-propargylamines
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Abstract Tetrasubstituted alkene-based 1,2,3,4-tetrahydroisoquinolines are synthesized via the formation of a cyclic carbopalladation complex followed by C-H bond activation of the sp2 carbon in arenes. This domino reaction proceeds with good selectivity and provides good yields of the products. The requisite starting materials are synthesized by copper(I) iodide catalyzed A3-coupling reactions.
- Naveen, Kanagaraj,Nandakumar, Avanashiappan,Perumal, Paramasivan Thirumalai
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p. 1633 - 1642
(2015/03/31)
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- Nickel-catalyzed alkynylation of anisoles via C-O bond cleavage
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A new cross-coupling reaction has been developed for the introduction of an alkyne moiety to an anisole derivative through C-O bond activation using an NHC ligand. This method has been used for direct alkynylation of a broad range of anisole derivatives a
- Tobisu, Mamoru,Takahira, Tsuyoshi,Ohtsuki, Akimichi,Chatani, Naoto
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p. 680 - 683
(2015/03/05)
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- Synthesis of phenanthrenes through copper-catalyzed cross-Coupling of N-tosylhydrazones with terminal alkynes
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A novel protocol for the synthesis of phenanthrenes through the copper-catalyzed reaction of aromatic tosylhydrazones with terminal alkynes is explored. The reaction proceeds via the formation of an allene intermediate and subsequent six-π-electron cyclization-isomerization, affording phenanthrene derivatives in good yields. The transformation can be performed in two ways:(1)with Ntosylhydrazones derived from [1,1'-biphenyl]-2-carbaldehydes and terminal alkynes as the starting materials and(2)with Ntosylhydrazones derived from aromatic aldehydes and 2-alkynyl biphenyls as the starting materials. This new phenanthrene synthesis uses readily available starting materials and a cheap copper catalyst and has a wide range of functional group compatibility.
- Hossain, Mohammad Lokman,Ye, Fei,Liu, Zhenxing,Xia, Ying,Shi, Yi,Zhou, Lei,Zhang, Yan,Wang, Jianbo
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p. 8689 - 8699
(2015/01/08)
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- Synthesis and structure-activity relationship of histone deacetylase (HDAC) inhibitors with triazole-linked cap group
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Histone deacetylase (HDAC) inhibition is a recent, clinically validated therapeutic strategy for cancer treatment. Small molecule HDAC inhibitors identified so far fall in to three distinct structural motifs: the zinc-binding group (ZBG), a hydrophobic linker, and a recognition cap group. Here we report the suitability of a 1,2,3-triazole ring as a surface recognition cap group-linking moiety in suberoylanilide hydroxamic acid-like (SAHA-like) HDAC inhibitors. Using "click" chemistry (Huisgen cycloaddition reaction), several triazole-linked SAHA-like hydroxamates were synthesized. Structure-activity relationship revealed that the position of the triazole moiety as well as the identity of the cap group markedly affected the in vitro HDAC inhibition and cell growth inhibitory activities of this class of compounds.
- Chen, Po C.,Patil, Vishal,Guerrant, William,Green, Patience,Oyelere, Adegboyega K.
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p. 4839 - 4853
(2008/12/21)
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- Palladium- and nickel-catalyzed cross-couplings of unsaturated halides bearing relatively acidic protons with organozinc reagents
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(Chemical Equation Presented) A wide range of polyfunctional aryl, heteroaryl, alkyl, and benzylic zinc reagents were coupled with unsaturated aryl halides bearing an acidic NH or OH proton, using Pd(OAc)2 (1 mol %) and S-Phos (2 mol %) as catalyst without the need of protecting groups. A similar nickel-catalyzed reaction is described. The relative kinetic basicity of organozinc compounds as well as their stability toward acidic protons is also described.
- Manolikakes, Georg,Munoz Hernandez, Carmen,Schade, Matthias A.,Metzger, Albrecht,Knochel, Paul
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supporting information; experimental part
p. 8422 - 8436
(2009/04/11)
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- Direct diazo-transfer reaction on β-lactam: Synthesis and preliminary biological activities of 6-triazolylpenicillanic acids
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In this study we report the first example of a direct diazo-transfer reaction on readily available 6-aminopenicillanates to give 6-azidopenicillanates in high yield. Subsequent Cu(I)-catalyzed Huisgen cycloaddition between these 6-azidopenicillanates and assorted terminal alkynes facilely furnished 6-triazolylpenicillanic acids. Preliminary biological screening indicates that these triazolylpenicillanic acids possess low to moderate antibacterial activities.
- Chen, Po C.,Wharton, Rebekah E.,Patel, Pratiq A.,Oyelere, Adegboyega K.
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p. 7288 - 7300
(2008/03/28)
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- Synthesis and inhibitory activity of 4-alkynyl and 4-alkenylquinazolines: Identification of new scaffolds for potent EGFR tyrosine kinase inhibitors
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The present study identified several 4-alkynyl and 4-alkenylquinazolines that serve as novel and potent EGFR tyrosine kinase inhibitors. The IC50 values of these compounds are in the nanomolar range. In addition, the 4-(4-phenylbut-1-yn/en-yl)q
- Kitano, Yasunori,Suzuki, Tsuyoshi,Kawahara, Eiji,Yamazaki, Takahisa
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p. 5863 - 5867
(2008/04/03)
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- 4-Aryl-1,2,3-triazole: A novel template for a reversible methionine aminopeptidase 2 inhibitor, optimized to inhibit angiogenesis in vivo
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Inhibitors of human methionine aminopeptidase type 2 (hMetAP2) are of interest as potential treatments for cancer. A new class of small molecule reversible inhibitors of hMetAP2 was discovered and optimized, the 4-aryl-1,2,3-triazoles. Compound 24, a potent inhibitor of cobalt-activated hMetAP2, also inhibits human and mouse endothelial cell growth. Using a mouse matrigel model, this reversible hMetAP2 inhibitor was also shown to inhibit angiogenesis in vivo.
- Kallander, Lara S.,Lu, Qing,Chen, Wenfang,Tomaszek, Thaddeus,Yang, Guang,Tew, David,Meek, Thomas D.,Hofmann, Glenn A.,Schulz-Pritchard, Christina K.,Smith, Ward W.,Janson, Cheryl A.,Ryan, M. Dominic,Zhang, Gui-Feng,Johanson, Kyung O.,Kirkpatrick, Robert B.,Ho, Thau F.,Fisher, Paul W.,Mattern, Michael R.,Johnson, Randall K.,Hansbury, Michael J.,Winkler, James D.,Ward, Keith W.,Veber, Daniel F.,Thompson, Scott K.
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p. 5644 - 5647
(2007/10/03)
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- Annulation selectivity in the coupling of Fischer carbene complexes with o-alkynylbiphenyl and o-alkynylstyrene derivatives
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The coupling of various Fischer carbene complexes with o-ethynylbiphenyl and an o-alkynylstyrene derivatives has been examined. In coupling reactions with methylcarbene and cyclopropylcarbene complexes, the major products are derived from C-H or C-C activation processes. In coupling reactions with phenylcarbene complexes, the major products are derived from the D?tz reaction.
- Jackson, Thaddeus J,Herndon, James W
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p. 3859 - 3868
(2007/10/03)
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- Synthesis of polyphenylene derivatives by thermolysis of enediynes and dialkynylaromatic monomers
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Described are the syntheses of substituted enediynes and dialkynylaromatics using Pd- or Pd/Cu-catalyzed cross coupling procedures. The products were then thermalized to afford the corresponding poly(p- phenylene)s, poly(1,4-naphthalene)s, poly(benzo[c]thiophene)s, and poly(dibenzothiophene)s. Fifteen examples are provided that show the scope of the polymerization process based upon substituent patterns and cyclization moieties. The superb thermal resiliency of the newly derived polymers is demonstrated using thermogravimetric analysis. The polymer structure was generally confirmed using IR data correlations to small molecules that resembled the polymers' repeat unit structure. Radical trapping of dimeric intermediates, that were analyzed by GCMS, further substantiated the proposed mechanistic route. The step-growth polymerization pattern was determined by monitoring the degree of monomer consumption versus the polymer molecular weight.
- John, Jens A.,Tour, James M.
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p. 15515 - 15534
(2007/10/03)
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- PHOSPHORUS-CONTAINING HMG-COA REDUCTASE INHIBITORS, NEW INTERMEDIATES AND METHOD
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Compounds which are useful as inhibitors of cholesterol biosynthesis and thus as hypocholesteroleumic agents are provided which have the structure STR1 wherein R is OH, or salts thereof or lower alkoxy; R. sup.x is H or alkyl;X is--CH 2--,--
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- Attribution de la configuration des orthobiphenyl-1 phenyl-1 methyl-2 ethylenes par resonance magnetique nucleaire du carbone-13. Synthese stereospecifique de l'isomere Z.
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Orthovinylbiphenyls are efficiently photocyclized to 9,10-dihydrophenantrenes which are of interest in their own right and as precursors of phenantrenes.Since we had previously determined the stereoselectivity of the cyclization of orthovinylbiphenyls while investigating the nature of the reactive state we found it useful to have available a straightforward method for assigning the configurations of these compounds.The method of Pascual and Tobey for evaluating the chemical shift of an olefinic proton have been tentatively applied to assign the Z and E configurations of 1-orthobiphenyl-1-phenyl-2-methylethylenes.The values calculated empirically, from model compounds, of the differential shielding between olefinic protons in both Z and E configurations are too close to be useful for assignment of the experimental values to specific configurations.By way of contrast a carbon-13 nuclear magnetic resonance study of model compounds such as 1,1,-diphenylethylene, 1-ortho-biphenyl-1-phenylethylene, and the 2-methylated compounds allows the assignment of configurations E and Z for the two isomers of 1-orthobiphenyl-1-phenyl-2-methylethylene since the methyl has a positive contribution to the chemical shift of the trans quaternary aromatic carbon and a negative one of the same amplitude for the cis quaternary aromatic carbon (γ effect).The assignment of 13C NMR signals of the olefinic carbons and of the quaternary aromatic carbons have been carried out from residual splitting of long-range 13C-1H coupling constants obtained by off-resonance irradiation.Specifically continuous wave irradiation at 8.66 ppm with a field γH2/2? ca. 350 Hz selectively decouples aromatic protons, and one can observe reduced splittings due to olefinic and aliphatic hydrogens.Assuming that 3Jtrans (13C-1H) > 3Jcis (13C-1H), the assignment of the quaternary aromatic carbon atom follows and makes it possible to measure the γ effect of the methyl group.To corroborate the assignment of configuration of 1-orthobiphenyl-1-phenyl-2-methylethylene we have performed a six step stereospecific synthesis of the Z isomer which takes advantage of the preferred syn addition of HBr to a triple bond in presence of HgBr2 and of the substitution with retention of an olefinic bromine by the phenyl gruoup of Ph2CuLi.
- Nourmamode, Aziz,Lapouyade, Rene,Barbe, Bernard,Petraud, Michel
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p. 207 - 213
(2007/10/02)
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