536-75-4Relevant academic research and scientific papers
Chemoselective Hydrogenation of Olefins Using a Nanostructured Nickel Catalyst
Klarner, Mara,Bieger, Sandra,Drechsler, Markus,Kempe, Rhett
supporting information, p. 2157 - 2161 (2021/05/21)
The selective hydrogenation of functionalized olefins is of great importance in the chemical and pharmaceutical industry. Here, we report on a nanostructured nickel catalyst that enables the selective hydrogenation of purely aliphatic and functionalized olefins under mild conditions. The earth-abundant metal catalyst allows the selective hydrogenation of sterically protected olefins and further tolerates functional groups such as carbonyls, esters, ethers and nitriles. The characterization of our catalyst revealed the formation of surface oxidized metallic nickel nanoparticles stabilized by a N-doped carbon layer on the active carbon support.
Ambient Hydrogenation and Deuteration of Alkenes Using a Nanostructured Ni-Core–Shell Catalyst
Beller, Matthias,Feng, Lu,Gao, Jie,Jackstell, Ralf,Jagadeesh, Rajenahally V.,Liu, Yuefeng,Ma, Rui
supporting information, p. 18591 - 18598 (2021/06/28)
A general protocol for the selective hydrogenation and deuteration of a variety of alkenes is presented. Key to success for these reactions is the use of a specific nickel-graphitic shell-based core–shell-structured catalyst, which is conveniently prepared by impregnation and subsequent calcination of nickel nitrate on carbon at 450 °C under argon. Applying this nanostructured catalyst, both terminal and internal alkenes, which are of industrial and commercial importance, were selectively hydrogenated and deuterated at ambient conditions (room temperature, using 1 bar hydrogen or 1 bar deuterium), giving access to the corresponding alkanes and deuterium-labeled alkanes in good to excellent yields. The synthetic utility and practicability of this Ni-based hydrogenation protocol is demonstrated by gram-scale reactions as well as efficient catalyst recycling experiments.
Scalable, Telescoped Hydrogenolysis-Enzymatic Decarboxylation Process for the Asymmetric Synthesis of (R)-α-Heteroaryl Propionic Acids
Blakemore, Caroline A.,France, Scott P.,Samp, Lacey,Nason, Deane M.,Yang, Eddie,Howard, Roger M.,Coffman, Karen J.,Yang, Qingyi,Smith, Aaron C.,Evrard, Edelweiss,Li, Wei,Dai, Linlin,Yang, Lixia,Chen, Zhiguang,Zhang, Qingli,He, Fangyan,Zhang, Jiesen
supporting information, p. 421 - 426 (2020/11/12)
Enantiopure α-aryl propionic acids are useful building blocks for pharmaceutical research and can be accessed enzymatically using arylmalonate decarboxylases (AMDases) from the corresponding malonic acids. However, the intrinsic instability of malonic acids is a major drawback to this approach in which spontaneous decarboxylation can occur, subsequently eroding enantioselectivity and giving rise to racemic products. This was particularly evident for a panel of N-heterocyclic propionic acids that we wished to access using the approach. Herein, we describe a process to overcome the spontaneous decarboxylation problem in which hydrogenolysis of the corresponding dibenzyl malonates was performed in a biphasic toluene-basic aqueous buffer mixture and telescoped into the subsequent AMDase step. This procedure enabled compounds to be accessed in high enantioselectivities and was successfully demonstrated on 120 g with high yield (76%) and ee (98%).
Metal-Organic Framework-Confined Single-Site Base-Metal Catalyst for Chemoselective Hydrodeoxygenation of Carbonyls and Alcohols
Antil, Neha,Kumar, Ajay,Akhtar, Naved,Newar, Rajashree,Begum, Wahida,Manna, Kuntal
supporting information, p. 9029 - 9039 (2021/06/28)
Chemoselective deoxygenation of carbonyls and alcohols using hydrogen by heterogeneous base-metal catalysts is crucial for the sustainable production of fine chemicals and biofuels. We report an aluminum metal-organic framework (DUT-5) node support cobalt(II) hydride, which is a highly chemoselective and recyclable heterogeneous catalyst for deoxygenation of a range of aromatic and aliphatic ketones, aldehydes, and primary and secondary alcohols, including biomass-derived substrates under 1 bar H2. The single-site cobalt catalyst (DUT-5-CoH) was easily prepared by postsynthetic metalation of the secondary building units (SBUs) of DUT-5 with CoCl2 followed by the reaction of NaEt3BH. X-ray photoelectron spectroscopy and X-ray absorption near-edge spectroscopy (XANES) indicated the presence of CoII and AlIII centers in DUT-5-CoH and DUT-5-Co after catalysis. The coordination environment of the cobalt center of DUT-5-Co before and after catalysis was established by extended X-ray fine structure spectroscopy (EXAFS) and density functional theory. The kinetic and computational data suggest reversible carbonyl coordination to cobalt preceding the turnover-limiting step, which involves 1,2-insertion of the coordinated carbonyl into the cobalt-hydride bond. The unique coordination environment of the cobalt ion ligated by oxo-nodes within the porous framework and the rate independency on the pressure of H2 allow the deoxygenation reactions chemoselectively under ambient hydrogen pressure.
Rethinking Basic Concepts-Hydrogenation of Alkenes Catalyzed by Bench-Stable Alkyl Mn(I) Complexes
Weber, Stefan,St?ger, Berthold,Veiros, Luis F.,Kirchner, Karl
, p. 9715 - 9720 (2019/10/14)
An efficient additive-free manganese-catalyzed hydrogenation of alkenes to alkanes with molecular hydrogen is described. This reaction is atom economic, implementing an inexpensive, earth-abundant nonprecious metal catalyst. The most efficient precatalyst is the bench-stable alkyl bisphosphine Mn(I) complex fac-[Mn(dippe)(CO)3(CH2CH2CH3)]. The catalytic process is initiated by migratory insertion of a CO ligand into the Mn-alkyl bond to yield an acyl intermediate which undergoes rapid hydrogenolysis to form the active 16e Mn(I) hydride catalyst [Mn(dippe)(CO)2(H)]. A range of mono- A nd disubstituted alkenes were efficiently converted into alkanes in good to excellent yields. The hydrogenation of 1-alkenes and 1,1-disubstituted alkenes proceeds at 25 °C, while 1,2-disubstituted alkenes require a reaction temperature of 60 °C. In all cases, a catalyst loading of 2 mol % and a hydrogen pressure of 50 bar were applied. A mechanism based on DFT calculations is presented, which is supported by preliminary experimental studies.
Preparation method of 4-ethylpyridine
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Paragraph 0060; 0068-0069; 0070; 0078-0079; 0080; 0088-0089, (2019/04/10)
The invention relates to the technical field of organic synthesis, in particular to a preparation method of 4-ethylpyridine. The preparation method of the 4-ethylpyridine comprises the following stepsof: mixing ethyl 4-picolinate with sodium ethoxide, heating to 90 to 110 DEG C, then dropwise adding ethyl acetate, and carrying out claisen condensation reaction, thus obtaining ethyl 3-oxo-3-(4-pyridyl) propionate; mixing the ethyl 3-oxo-3-(4-pyridyl) propionate, dimethyl sulfoxide and water, and carrying out heating treatment, thus obtaining 4-acetylpyridine; cooling after mixing glycol with potassium hydroxide, adding hydrazine hydrate, rising the temperature to 60 to 80 DEG C, then mixing with the 4-acetylpyridine, and carrying out reduction reaction, thus obtaining the 4-ethylpyridine.The 4-ethylpyridine prepared through the preparation method provided by the invention is higher in yield and purity.
Disilaruthena- and Ferracyclic Complexes Containing Isocyanide Ligands as Effective Catalysts for Hydrogenation of Unfunctionalized Sterically Hindered Alkenes
Sunada, Yusuke,Ogushi, Hajime,Yamamoto, Taiji,Uto, Shoko,Sawano, Mina,Tahara, Atsushi,Tanaka, Hiromasa,Shiota, Yoshihito,Yoshizawa, Kazunari,Nagashima, Hideo
supporting information, p. 4119 - 4134 (2018/03/29)
Disilaferra- and disilaruthenacyclic complexes containing mesityl isocyanide as a ligand, 3′ and 4′, were synthesized and characterized by spectroscopy and crystallography. Both 3′ and 4′ showed excellent catalytic activity for the hydrogenation of alkenes. Compared with iron and ruthenium carbonyl analogues, 1′ and 2′, the isocyanide complexes 3′ and 4′ were more robust under the hydrogenation conditions, and were still active even at higher temperatures (～80 °C) under high hydrogen pressure (～20 atm). The iron complex 3′ exhibited the highest catalytic activity toward hydrogenation of mono-, di-, tri-, and tetrasubstituted alkenes among currently reported iron catalysts. Ruthenium complex 4′ catalyzed hydrogenation under very mild conditions, such as room temperature and 1 atm of H2. The remarkably high catalytic activity of 4′ for hydrogenation of unfunctionalized tetrasubstituted alkenes was especially notable, because it was comparable to the activity of iridium complexes reported by Crabtree and Pfaltz, which are catalysts with the highest activity in the literature. DFT calculations suggested two plausible catalytic cycles, both of which involved activation of H2 assisted by the metal-silicon bond through σ-bond metathesis of late transition metals (oxidative hydrogen migration). The linear structure of M C≡N - C (ipso carbon of the mesityl group) played an essential role in the efficient hydrogenation of sterically hindered tetrasubstituted alkenes.
Divalent Silicon-Assisted Activation of Dihydrogen in a Bis(N-heterocyclic silylene)xanthene Nickel(0) Complex for Efficient Catalytic Hydrogenation of Olefins
Wang, Yuwen,Kostenko, Arseni,Yao, Shenglai,Driess, Matthias
supporting information, p. 13499 - 13506 (2017/10/05)
The first chelating bis(N-heterocyclic silylene)xanthene ligand [SiII(Xant)SiII] as well as its Ni complexes [SiII(Xant)SiII]Ni(η2-1,3-cod) and [SiII(Xant)SiII]Ni(PMe3)2 were synthesized and fully characterized. Exposing [SiII(Xant)SiII]Ni(η2-1,3-cod) to 1 bar H2 at room temperature quantitatively generated an unexpected dinuclear hydrido Ni complex with a four-membered planar Ni2Si2 core. Exchange of the 1,3-COD ligand by PMe3 led to [SiII(Xant)SiII]Ni(PMe3)2, which could activate H2 reversibly to afford the first SiII-stabilized mononuclear dihydrido Ni complex characterized by multinuclear NMR and single-crystal X-ray diffraction analysis. [SiII(Xant)SiII]Ni(η2-1,3-cod) is a strikingly efficient precatalyst for homogeneous hydrogenation of olefins with a wide substrate scope under 1 bar H2 pressure at room temperature. DFT calculations reveal a novel mode of H2 activation, in which the SiII atoms of the [SiII(Xant)SiII] ligand are involved in the key step of H2 cleavage and hydrogen transfer to the olefin.
A Bifunctional Reagent Designed for the Mild, Nucleophilic Functionalization of Pyridines
Fier, Patrick S.
supporting information, p. 9499 - 9502 (2017/07/24)
Herein is reported the design and application of a reagent for the direct functionalization of pyridines. These reactions occur under mild conditions and exhibit broad functional group tolerance, enabling the late-stage functionalization of drug-like molecules. The reagent can be easily prepared on large scale from inexpensive reagents, and reacts in the title reaction with acetonitrile, sodium chloride, and sodium methanesulfonate as the sole byproducts. Although this Communication focuses primarily on reactions with cyanide as nucleophile, preliminary experiments with other nucleophiles foreshadow the broad reaching synthetic utility of this approach.
Well-Defined Cobalt(I) Dihydrogen Catalyst: Experimental Evidence for a Co(I)/Co(III) Redox Process in Olefin Hydrogenation
Tokmic, Kenan,Markus, Charles R.,Zhu, Lingyang,Fout, Alison R.
supporting information, p. 11907 - 11913 (2016/10/07)
The synthesis of a cobalt dihydrogen CoI-(H2) complex prepared from a CoI-(N2) precursor supported by a monoanionic pincer bis(carbene) ligand, MesCCC (MesCCC = bis(mesityl-benzimidazol-2-ylidene)phenyl), is described. This species is capable of H2/D2 scrambling and hydrogenating alkenes at room temperature. Stoichiometric addition of HCl to the CoI-(N2) cleanly affords the CoIII hydridochloride complex, which, upon the addition of Cp2ZrHCl, evolves hydrogen gas and regenerates the CoI-(N2) complex. Furthermore, the catalytic olefin hydrogenation activity of the CoI species was studied by using multinuclear and parahydrogen (p-H2) induced polarization (PHIP) transfer NMR studies to elucidate catalytically relevant intermediates, as well as to establish the role of the CoI-(H2) in the CoI/CoIII redox cycle.
