221230-45-1Relevant academic research and scientific papers
Alumina-Mediated π-Activation of Alkynes
Akhmetov, Vladimir,Amsharov, Konstantin,Feofanov, Mikhail,Sharapa, Dmitry I.
, 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.
Palladium-Catalyzed Synthesis of Tetrasubstituted Olefins by Triple Domino Process
Naveen, Kanagaraj,Nikson, Savariyappan Albert,Perumal, Paramasivan Thirumalai
supporting information, p. 2407 - 2413 (2017/07/22)
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.).
Metal-free synthesis of 2-aminonaphthalenes by intramolecular transannulation of 1-sulfonyl-4-(2-alkenylphenyl)-1,2,3-triazoles
Xu, Ze-Feng,Yu, Xing,Yang, Dongdong,Li, Chuan-Ying
supporting information, p. 3161 - 3164 (2017/04/21)
A facile metal-free synthesis of naphthalenes by intramolecular transannulation of 1-sulfonyl-4-(2-alkenylphenyl)-1,2,3-triazoles was realized. The in situ formed ketenimine was proposed as the key intermediate, and the desired 2-aminonaphthalenes were generated in up to 87% yield in refluxing 1,2-dichloroethane without any catalyst or additive.
Bis(cyclopropenium)phosphines: Synthesis, Reactivity, and Applications
Mehler, Gerlinde,Linowski, Pawel,Carreras, Javier,Zanardi, Alessandro,Dube, Jonathan W.,Alcarazo, Manuel
, p. 15320 - 15327 (2016/10/13)
A straightforward route for the preparation of a set of bis(cyclopropenium)-substituted phosphines is reported. Due to their dicationic nature, these ligands depict an excellent π-acceptor character. The effect of the ligand substituent pattern on the catalytic activity of the metal complexes thereof derived is also studied. Whereas sterically demanding biaryl groups directly attached to the phosphorus atom seem to facilitate elementary steps such as the product release from the catalyst, long chain dialkylamino groups on the cyclopropenium units maximize the catalysts solubility and, thus, allow the use of typical apolar solvents such as toluene. Importantly, all new ligands prepared can be easily handled in air. Finally, the impact of the newly prepared dicationic phosphines in hydroarylation reactions is demonstrated. In particular, their use in the synthesis of several naphtho[1,2-b]furanes and naturally occurring naphthalene derivatives such as Calanquinone C is reported.
C-H bond functionalization in the synthesis of fused 1,2,3-triazoles
Panteleev, Jane,Geyer, Karolin,Aguilar-Aguilar, Angelica,Wang, Letian,Lautens, Mark
supporting information; experimental part, p. 5092 - 5095 (2011/02/22)
A highly modular approach to fused 1,2,3-triazoles has been developed featuring a one-pot procedure combining copper(I) catalyzed azide-alkyne cycloaddition and palladium-catalyzed C-H bond functionalization. A class of structurally unique heterocycles was synthesized in good yields.
Intramolecular reactions of alkynes with furans and electron rich arenes catalyzed by PtCl2: The role of platinum carbenes as intermediates
Martin-Matute, Belen,Nevado, Cristina,Cardenas, Diego J.,Echavarren, Antonio M.
, p. 5757 - 5766 (2007/10/03)
5-(2-Furyl)-1-alkynes react, with PtCl2 as catalyst, to give phenols. On the basis of DFT calculations, a cyclopropyl platinacarbene complex was found as the key intermediate in the process. The cyclopropane and dihydrofuran rings of this intermediate open to form a carbonyl compound, which reacts with the platinum carbene to form an oxepin, which is in equilibrium with an arene oxide. When the reaction is carried out in the presence of water, dicarbonyl compounds are obtained, which support the proposed mechanism. Other cyclizations of alkynes with furans or electron-rich arenes give products of apparent Friedel-Crafts-type reactions, although these processes could also proceed by pathways involving the formation of cyclopropyl platinum carbenes.
