13203-60-6Relevant academic research and scientific papers
Alumina-Mediated π-Activation of Alkynes
Akhmetov, Vladimir,Amsharov, Konstantin,Feofanov, Mikhail,Sharapa, Dmitry I.
supporting information, p. 15420 - 15426 (2021/09/30)
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.
Aerobic Cu-catalyzed oxidative 1?:?2 coupling of benzynes with terminal alkynes
Lu, Tianhao,Shen, Yong,Wang, Min,Zhang, Zibing,Li, Shijun,Xie, Chunsong
, p. 8214 - 8217 (2020/08/17)
Cu-Catalyzed oxidative 1?:?2 couplings of arynes with nucleophilic terminal alkynes under aerobic conditions are described herein. A mechanistic investigation revealed a plausible involvement of an aryl-Cu(iii)-generating pathway. By this method, ubiquitous arenediynes can be efficiently assembled in a single step under mild conditions. This journal is
Arylation of Terminal Alkynes by Aryl Iodides Catalyzed by a Parts-per-Million Loading of Palladium Acetate
Hamasaka, Go,Roy, David,Tazawa, Aya,Uozumi, Yasuhiro
, p. 11640 - 11646 (2019/12/02)
Arylation of terminal alkynes (16 varieties) by aryl iodides (28 varieties) was achieved with a mol ppm loading level of palladium catalyst, where a variety of functional groups including heteroarenes were tolerated. Thus, the arylations were carried out in the presence of palladium acetate at ppm loadings and potassium carbonate in ethanol at 80 °C to give the corresponding internal alkynes in good to excellent yields. Synthesis of 2-phenyl-3-(phenylalkynyl)benzofuran was achieved by iterative use of the alkyne arylation under mol ppm catalytic conditions. Reaction-rate analysis, transmission electron microscopic (TEM) examination of the reaction mixture, and mercury-amalgamation test were performed to gain insight into the active species of the highly active ppm catalytic species. TEM examination of the reaction mixture revealed that palladium nanoparticles were generated in situ under the reaction conditions, and their cluster size was variable during the catalytic reaction. A variation in size of palladium particles suggested that the composition-decomposition process of Pd aggregates should take place in situ via monomeric palladium(0) species and/or fine palladium(0) clusters, which might be real catalytic species in this reaction.
Borylative cyclisation of diynes using BCl3 and borocations
Warner, Andrew J.,Enright, Kieron M.,Cole, John M.,Yuan, Kang,McGough, John S.,Ingleson, Michael J.
supporting information, p. 5520 - 5525 (2019/06/13)
The borylative cyclisation of 1,2-dialkynyl benzenes with BCl3 leads to dibenzopentalenes (via intramolecular SEAr) or benzofulvenes (via chloride addition) depending on substituents, with stabilised vinyl cation intermediates (e.g.
Copper-Catalyzed Three-Component Carboamination of Arynes: Expeditious Synthesis of o-Alkynyl Anilines and o-Benzoxazolyl Anilines
Niu, Sheng-Li,Hu, Jiangtao,He, Kuicheng,Chen, Ying-Chun,Xiao, Qing
supporting information, p. 4250 - 4254 (2019/06/07)
A copper-catalyzed three-component reaction of in situ formed arynes, terminal alkynes, and O-benzoylhydroxylamines has been developed. By adjusting reaction conditions, the nucleophiles in this transformation can be extended from terminal alkynes to benzoxazoles. These procedures provide a modular and facile approach to o-alkynyl anilines and o-benzoxazolyl anilines from easily available substrates in only one step.
Cross-coupling reactions using porous multipod Cu2O microcrystals as recoverable catalyst in aqueous media
Tang, Lin,Wu, Chaoting,Hu, Qiyan,Li, Qian,Zhang, Wu
, (2017/09/06)
Porous multipod Cu2O microcrystals were found to be an efficient, highly recyclable and eco-friendly catalyst for the cross-coupling reactions of aryl halides and terminal alkynes with high yields in aqueous media. Noteworthy, the Cu2O catalyst can be reused for several times without significant decrease in catalytic activity.
On the Gold-Catalyzed Generation of Vinyl Cations from 1,5-Diynes
Wurm, Thomas,Bucher, Janina,Duckworth, Sarah B.,Rudolph, Matthias,Rominger, Frank,Hashmi, A. Stephen K.
supporting information, p. 3364 - 3368 (2017/03/17)
Conjugated 1,5-diynes bearing two aromatic units at the alkyne termini were converted in the presence of a gold catalyst. Under mild conditions, aryl-substituted dibenzopentalenes were generated. Calculations predict that aurated vinyl cations are key intermediates of the reaction. A bidirectional approach provided selective access to the angular annulated product in high yield, which was explained by calculations.
DNA-supported palladium nanoparticles as a reusable catalyst for the copper- and ligand-free Sonogashira reaction
Camacho, Ana Silvia,Martín-García, Iris,Contreras-Celedón, Claudia,Chacón-García, Luis,Alonso, Francisco
, p. 2262 - 2273 (2017/07/24)
DNA nanotechnology has recently emerged as a powerful discipline with diverse applications. However, studies focused on the combination of DNA and metal nanoparticles for catalyst design are scanty. We have prepared a catalyst composed of palladium nanoparticles supported on DNA which has been characterised by TEM, SEM, EDX, UV, FTIR and XPS. The catalyst, mainly composed of Pd(ii) and Pd(iv) species in the form of oxides, has been effectual in the copper- and ligand-free Sonogashira-Hagihara coupling of aryl iodides with terminal aromatic and aliphatic alkynes. The products are obtained in 54-86% isolated yields using low catalyst loading (0.5 mol%) under mild conditions (65 °C) in methanol without air exclusion. Moreover, the catalyst can be easily recovered and reused in five cycles and shows better performance than an array of commercial palladium catalysts. The mechanistic aspects of the reaction are also tackled in detail.
Orbital Crossings Activated through Electron Injection: Opening Communication between Orthogonal Orbitals in Anionic C1-C5 Cyclizations of Enediynes
Peterson, Paul W.,Shevchenko, Nikolay,Breiner, Boris,Manoharan, Mariappan,Lufti, Forat,Delaune, Jess,Kingsley, Margaret,Kovnir, Kirill,Alabugin, Igor V.
supporting information, p. 15617 - 15628 (2016/12/16)
Generally, the long-range electronic communication between spatially orthogonal orbitals is inefficient and limited to field and inductive effects. In this work, we provide experimental evidence that such communication can be achieved via intramolecular electron transfer between two degenerate and mutually orthogonal frontier molecular orbitals (MOs) at the transition state. Interaction between orthogonal orbitals is amplified when the energy gap between these orbitals approaches zero, or at an “orbital crossing”. The crossing between two empty or two fully occupied MOs, which do not lead to stabilization, can be “activated” when one of the empty MOs is populated (i.e., electron injection) or one of the filled MOs is depopulated (i.e., hole injection). In reductive cycloaromatization reactions, such crossings define transition states with energies defined by both the in-plane and out-of-plane π-systems. Herein, we provide experimental evidence for the utility of this concept using orbital crossings in reductive C1-C5 cycloaromatization reactions of enediynes. Communication with remote substituents via orbital crossings greatly enhances regioselectivity of the ring closure step in comparison to the analogous radical cyclizations. We also present photophysical data pertaining to the efficiency of electron injection into the benzannelated enediynes.
Regioselective 5-endo-dig Electrophilic Iodocyclization of Enediynes: A Convenient Route to Iodo-substituted Indenes and Cyclopenta-Fused Arenes
Saunthwal, Rakesh K.,Danodia, Abhinandan K.,Patel, Monika,Kumar, Sushil,Verma, Akhilesh K.
supporting information, p. 3001 - 3007 (2016/11/13)
An efficient iodine-mediated regioselective tandem approach for the synthesis of symmetric and asymmetric iodo-substituted indenes and stereoselective cyclopenta [b]pyridine/thiophenes from easily accessible enediynes that proceeds by in situ formation of an iodonium intermediate followed by a regioselective 5-endo-dig cyclization has been described. The intramolecular electrophilic iodocyclization was selectively triggered by a distribution of electronic density along the alkyne bond. Subsequently, the iodo-substituted indenes were diversified by employing palladium-catalyzed cross-coupling reactions and the coupled products were further confirmed by X-ray crystallographic studies.
