2132-62-9Relevant academic research and scientific papers
Lewis acid activation of molybdenum nitrides for alkyne metathesis
Finke, Aaron D.,Moore, Jeffrey S.
, p. 7939 - 7941 (2010)
The substantial kinetic barrier to molybdenum nitride-alkyne metathesis is facilitated by precomplexation of the borane Lewis acid B(C6F 5)3, providing convenient access to metathesis-active molybdenum alkylidynes. Spectroscopic and X-ray structural analysis suggest MoN bond weakening upon borane complexation.
Impact of Ligands and Metals on the Formation of Metallacyclic Intermediates and a Nontraditional Mechanism for Group VI Alkyne Metathesis Catalysts
Thompson, Richard R.,Rotella, Madeline E.,Zhou, Xin,Fronczek, Frank R.,Gutierrez, Osvaldo,Lee, Semin
, p. 9026 - 9039 (2021)
The intermediacy of metallacyclobutadienes as part of a [2 + 2]/retro-[2 + 2] cycloaddition-based mechanism is a well-established paradigm in alkyne metathesis with alternative species viewed as off-cycle decomposition products that interfere with efficient product formation. Recent work has shown that the exclusive intermediate isolated from a siloxide podand-supported molybdenum-based catalyst was not the expected metallacyclobutadiene but instead a dynamic metallatetrahedrane. Despite their paucity in the chemical literature, theoretical work has shown these species to be thermodynamically more stable as well as having modest barriers for cycloaddition. Consequentially, we report the synthesis of a library of group VI alkylidynes as well as the roles metal identity, ligand flexibility, secondary coordination sphere, and substrate identity all have on isolable intermediates. Furthermore, we report the disparities in catalyst competency as a function of ligand sterics and metal choice. Dispersion-corrected DFT calculations are used to shed light on the mechanism and role of ligand and metal on the intermediacy of metallacyclobutadiene and metallatetrahedrane as well as their implications to alkyne metathesis.
Synthesis of symmetrical diarylalkynes by double stille coupling of bis(tributylstannyl)acetylene
Cummins, Clark H.
, p. 857 - 860 (1994)
Treatment of bis(tributylstannyl)acetylene with two equivalents of an aryl iodide in the presence of tetrakis(triphenylphosphine)palladium (0) affords good yields of the symmetrical diarylalkyne. This approach provides a convenient and safe alternative to
183W NMR Spectroscopy Guides the Search for Tungsten Alkylidyne Catalysts for Alkyne Metathesis
Copéret, Christophe,Fürstner, Alois,Gordon, Christopher P.,Hillenbrand, Julius,Leutzsch, Markus
, p. 21758 - 21768 (2020)
Triarylsilanolates are privileged ancillary ligands for molybdenum alkylidyne catalysts for alkyne metathesis but lead to disappointing results and poor stability in the tungsten series. 1H,183W heteronuclear multiple bond correlation spectroscopy, exploiting a favorable 5J-coupling between the 183W center and the peripheral protons on the alkylidyne cap, revealed that these ligands upregulate the Lewis acidity to an extent that the tungstenacyclobutadiene formed in the initial [2+2] cycloaddition step is over-stabilized and the catalytic turnover brought to a halt. Guided by the 183W NMR shifts as a proxy for the Lewis acidity of the central atom and by an accompanying chemical shift tensor analysis of the alkylidyne unit, the ligand design was revisited and a more strongly π-donating all-alkoxide ligand prepared. The new expanded chelate complex has a tempered Lewis acidity and outperforms the classical Schrock catalyst, carrying monodentate tert-butoxy ligands, in terms of rate and functional-group compatibility.
Stabilizing Pentacene by Cyclopentannulation
Bheemireddy, Sambasiva R.,Ubaldo, Pamela C.,Rose, Peter W.,Finke, Aaron D.,Zhuang, Junpeng,Wang, Lichang,Plunkett, Kyle N.
, p. 15762 - 15766 (2015)
A new class of stabilized pentacene derivatives with externally fused five-membered rings are prepared by means of a key palladium-catalyzed cyclopentannulation step. The target compounds are synthesized by chemical manipulation of a partially saturated 6,13-dibromopentacene precursor that can be fully aromatized in a final step through a DDQ-mediated dehydrogenation reaction (DDQ=2,3-dichloro-5,6-dicyano-1,4-benzoquinone). The new 1,2,8,9-tetraaryldicyclopenta[fg,qr]pentacene derivatives have narrow energy gaps of circa 1.2 eV and behave as strong electron acceptors with lowest unoccupied molecular orbital energies between -3.81 and -3.90 eV. Photodegradation studies reveal the new compounds are more photostable than 6,13-bis(triisopropylsilylethynyl)pentacene (TIPS-pentacene). Five in a row: A palladium-catalyzed cyclopentannulation followed by a DDQ-mediated dehydrogenation converts a partially hydrogenated pentacene precursor into stabilized pentacenes. These pentacene derivatives are excellent electron acceptors and have small energy gaps. DDQ=2,3-dichloro-5,6-dicyano-1,4-benzoquinone.
Hexaphenylbenzene as a rigid template for the straightforward syntheses of "star-shaped" glycodendrimers
Chabre, Yoann M.,Brisebois, Patrick P.,Abbassi, Leila,Kerr, Sheena C.,Fahy, John V.,Marcotte, Isabelle,Roy, Rene
, p. 724 - 727 (2011)
Original glycodendrimers emanating from propargylated hexaphenylbenzene cores and containing up to 54 peripheral sugar ligands have been synthesized by Cu(I)-catalyzed [1,3]-dipolar cycloadditions using both convergent and divergent approaches.
Synthesis of symmetrical diarylalkyne from palladium-catalyzed decarboxylative couplings of propiolic acid and aryl bromides under water
Park, Kyungho,Bae, Goun,Park, Ahbyeol,Kim, Yong,Choe, Jaehoon,Song, Kwang Ho,Lee, Sunwoo
, p. 576 - 580 (2011)
Symmetric diarylalkynes were obtained from the decarboxylative coupling reactions of aryl bromides and propiolic acid in water solvent condition. In the presence of phase transfer surfactant C18H37N(CH 3)3Cl, the catalytic system of both Pd(PPh 3)2Cl2/dppb and Pd(TPPMS)2Cl 2/TPPMS afforded the desired coupled products in good yields.
Reaction of elemental phosphorus with α-methylstyrenes: One-pot synthesis of secondary and tertiary phosphines, prospective bulky ligands for Pd(II) catalysts
Artem'ev, Alexander V.,Malysheva, Svetlana F.,Gusarova, Nina K.,Belogorlova, Nataliya A.,Sukhov, Boris G.,Sutyrina, Anastasiya O.,Matveeva, Elena A.,Vasilevsky, Sergey F.,Govdi, Anastasiya I.,Gatilov, Yuriy V.,Albanov, Alexander I.,Trofimov, Boris A.
, p. 443 - 450 (2016)
α-Methylstyrene and 4-chloro-α-methylstyrene react readily with elemental (red) phosphorus under microwave-irradiation in the superbase KOH/DMSO suspension to afford, depending on the reactant ratio and reaction time, either corresponding bis(2-arylpropyl
The use of calcium carbide in one-pot synthesis of symmetric diaryl ethynes
Zhang, Weiwei,Wu, Huayue,Liu, Zhiqing,Zhong, Ping,Zhang, Lin,Huang, Xiaobo,Cheng, Jiang
, p. 4826 - 4828 (2006)
An efficient Pd-catalyzed copper and amine free coupling reaction of acetylene and aryl bromides was achieved with calcium carbide as an acetylene source, using inorganic base and easily prepared, air-stable aminophosphine ligand in common organic solvents, providing symmetric diaryl ethynes in one-pot with yields ranged from moderate to excellent. The Royal Society of Chemistry 2006.
Rhodium-catalyzed asymmetric synthesis of silicon-stereogenic dibenzosiloles by enantioselective[2+2+2] cycloaddition
Shintani, Ryo,Takagi, Chihiro,Ito, Tomoaki,Naito, Masanobu,Nozaki, Kyoko
, p. 1616 - 1620 (2015)
A rhodium-catalyzed asymmetric synthesis of silicon-stereogenic dibenzosiloles has been developed through a [2+2+2] cycloaddition of silicon-containing prochiral triynes with internal alkynes. High yields and enantioselectivities have been achieved by emp
