42036-72-6Relevant academic research and scientific papers
Dilithium Amides as a Modular Bis-Anionic Ligand Platform for Iron-Catalyzed Cross-Coupling
Neate, Peter G.N.,Zhang, Bufan,Conforti, Jessica,Brennessel, William W.,Neidig, Michael L.
supporting information, p. 5958 - 5963 (2021/08/18)
Dilithium amides have been developed as a bespoke and general ligand for iron-catalyzed Kumada-Tamao-Corriu cross-coupling reactions, their design taking inspiration from previous mechanistic and structural studies. They allow for the cross-coupling of alkyl Grignard reagents with sp2-hybridized electrophiles as well as aryl Grignard reagents with sp3-hybridized electrophiles. This represents a rare example of a single iron-catalyzed system effective across diverse coupling reactions without significant modification of the catalytic protocol, as well as remaining operationally simple.
Ruthenium-Catalyzed E-Selective Partial Hydrogenation of Alkynes under Transfer-Hydrogenation Conditions using Paraformaldehyde as Hydrogen Source
Fetzer, Marcus N. A.,Tavakoli, Ghazal,Klein, Axel,Prechtl, Martin H. G.
, p. 1317 - 1325 (2021/02/11)
E-alkenes were synthesized with up to 100 % E/Z selectivity via ruthenium-catalyzed partial hydrogenation of different aliphatic and aromatic alkynes under transfer-hydrogenation conditions. Paraformaldehyde as a safe, cheap and easily available solid hydrogen carrier was used for the first time as hydrogen source in the presence of water for transfer-hydrogenation of alkynes. Optimization reactions showed the best results for the commercially available binuclear [Ru(p-cymene)Cl2]2 complex as pre-catalyst in combination with 2,2-bis(diphenylphosphino)-1,1-binaphthyl (BINAP) as ligand (1 : 1 ratio per Ru monomer to ligand). Mechanistic investigations showed that the origin of E-selectivity in this reaction is the fast Z to E isomerization of the formed alkenes. Mild reaction conditions plus the use of cheap, easily available and safe materials as well as simple setup and inexpensive catalyst turn this protocol into a feasible and promising stereo complementary procedure to the well-known Z-selective Lindlar reduction in late-stage syntheses. This procedure can also be used for the production of deuterated alkenes simply using d2-paraformaldehyde and D2O mixtures.
Dinuclear cobalt complex-catalyzed stereodivergent semireduction of alkynes: Switchable selectivities controlled by H2O
Chen, Ke,Zhu, Hongdan,Li, Yuling,Peng, Qian,Guo, Yinlong,Wang, Xiaoming
, p. 13696 - 13705 (2021/11/16)
Catalytic semireduction of internal alkynes to alkenes is very important for organic synthesis. Although great success has been achieved in this area, switchable Z/E stereoselectivity based on a single catalyst for the semireduction of internal alkynes is a longstanding challenge due to the multichemo- and stereoselectivity, especially based on less-expensive earth-abundant metals. Herein, we describe a switchable semireduction of alkynes to (Z)- or (E)-alkenes catalyzed by a dinuclear cobalt complex supported by a macrocyclic bis pyridyl diimine (PDI) ligand. It was found that cis-reduction of the alkyne occurs first and the Z-E alkene stereoisomerization process is formally controlled by the amount of H2O, since the concentration of H2O may influence the catalytic activity of the catalyst for isomerization. Therefore, this protocol provides a facile way to switch to either the (Z)- or (E)-olefin isomer in a single transformation by adjusting the amount of water.
Precatalyst-Enabled Selectivity: Enantioselective NiH-Catalyzed anti-Hydrometalative Cyclization of Alkynones to Endo- and Heterocyclic Allylic Alcohols
Li, Qi-Yang,Liu, Wen-Bo,Zeng, Hai-Xiang,Zhang, Xiao-Wen,Zhu, Ming-Hui
supporting information, p. 27225 - 27229 (2021/12/08)
A highly enantioselective NiH-catalyzed hydrocyclization of alkynones with unparalleled anti- and endocyclic selectivities is described. The choice of the precatalysts has significant influence in tuning the regio- and enantioselectivity. Using Ni(OTs)su
A Bidentate Ru(II)-NC Complex as a Catalyst for Semihydrogenation of Alkynes to (E)-Alkenes with Ethanol
Chen, Dafa,Gong, Dawei,Hu, Bowen,Kong, Degong,Xia, Haiping,Yang, Weiwei
, (2020/03/19)
Four Ru(II)-NC complexes were tested as catalysts for semihydrogenation of internal alkynes to (E)-alkenes with ethanol, and the complex {(C5H4N)(C6H4)}RuCl(CO)(PPh3)2 (1a) showed the highest activity. The reactions proceeded well with 1 mol % catalyst loading and 0.1 equiv of t-BuONa at 110 °C for 1 h, and 32 alkenes were synthesized with excellent E:Z selectivity. This is the first ruthenium-catalyzed semihydrogenation of internal alkynes to (E)-alkenes using ethanol as the hydrogen donor.
Covalent Organic Framework as a Heterogeneous Ligand for the Regioselective Oxidative Heck Reaction
Han, Jiyao,Sun, Xiaowei,Wang, Xiao,Wang, Qiong,Hou, Shenghuai,Song, Xin,Wei, Yingqin,Wang, Rongyu,Ji, Wenhua
supporting information, p. 1480 - 1484 (2020/03/13)
A simple imine-based covalent organic framework (COF) as heterogeneous ligand for PdII-promoted Heck reaction is reported. Good regioselectivity for a wide range of electronically unbiased olefins is obtained (linear/branched >100:1 in most cases). Related tests and density functional theory calculations are used to explore the reason underlying the high selectivity. This research opens a route for COF as an intriguing platform to control regioselectivity catalysis.
A Highly Reduced Ni-Li-Olefin Complex for Catalytic Kumada-Corriu Cross-Couplings
Nattmann, Lukas,Lutz, Sigrid,Ortsack, Pascal,Goddard, Richard,Cornella, Josep
supporting information, p. 13628 - 13633 (2018/10/24)
The catalytic activity of a highly reduced Ni catalyst in the context of a Kumada-Corriu cross-coupling has been studied. This nickel complex is characterized by its high electron density, stabilized by simple olefin ligands in combination with two Li ions. Landmark reactivity has been found with this precatalyst which operates at cryogenic temperatures, thus allowing the presence of sensitive functionalities. Structural elucidation of oxidative addition intermediates and their reactivity suggest highly reduced species being operative in the C-C bond forming event.
Metal-Catalyzed Remote Functionalization of ω-Ene Unsaturated Ethers: Towards Functionalized Vinyl Species
Ho, Guo-Ming,Judkele, Lina,Bruffaerts, Jeffrey,Marek, Ilan
, p. 8012 - 8016 (2018/06/29)
The combined ruthenium-catalyzed chain walking with the nickel-catalyzed cross-coupling reaction of ω-alkenyl ethers provide a unique entry to functionalized vinyl species. This transformation illustrates the power and flexibility of remote functionalization by demonstrating the compatibility of two independent reactions involving unrelated sites.
Iron-Catalyzed Cross-Coupling of Alkenyl Acetates
G?rtner, Dominik,Stein, André Luiz,Grupe, Sabine,Arp, Johannes,Von Wangelin, Axel Jacobi
supporting information, p. 10545 - 10549 (2015/09/02)
Stable C-O linkages are generally unreactive in cross-coupling reactions which mostly employ more electrophilic halides or activated esters (triflates, tosylates). Acetates are cheap and easily accessible electrophiles but have not been used in cross-couplings because the strong C-O bond and high propensity to engage in unwanted acetylation and deprotonation. Reported herein is a selective iron-catalyzed cross-coupling of diverse alkenyl acetates, and it operates under mild reaction conditions (0 C, 2 h) with a ligand-free catalyst (1-2 mol%). Iron clad: Acetates are underutilized electrophiles in metal-catalyzed cross-coupling reactions because of the strong alkenyl C-O bond and their propensity to engage in unwanted reactions. Combination of a ligand-free low-valent Fe catalyst with nucleophilic organomagnesium reagents, low temperature, and short reaction times results in highly selective cross-couplings with alkenyl acetates.
