98-52-2Relevant academic research and scientific papers
UNUSUAL HIGH REACTIVITIES OF 5α- AND 5β-CHOLESTAN-3-ONES IN THE HYDROGENATION CATALYZED BY PALLADIUM. EVIDENCE FOR AN ATTRACTIVE INTERACTION OF THE STEROID α-FACE WITH PALLADIUM
Nishimura, Shigeo,Murai, Mikio,Shiota, Michio
, p. 1239 - 1242 (1980)
5α- And 5β-cholestan-3-ones are 30 and 17 times as reactive as 4-t-butylcyclohexanone in Pd catalyzed competitive hydrogenation in t-BuOH.The high reactivity of the steroid ketones and unusual hydrogenation stereochemistry on Pd have been explained on the basis of an attractive interaction of the steroid α-face with Pd.
SOMC?Periodic Mesoporous Silica Nanoparticles: Meerwein-Ponndorf-Verley Reduction Promoted by Immobilized Rare-Earth-Metal Alkoxides
Anwander, Reiner,Bock, Lorenz,Kramer, Markus,Liang, Yucang,Maichle-M?ssmer, C?cilia,Tran, Xuan
, p. 1046 - 1058 (2020)
The Meerwein-Ponndorf-Verley (MPV) reduction is a reaction that offers a mild reduction of aldehydes and ketones to the corresponding alcohols. Although described as a catalytic reaction, its real-life applicability suffers from the necessity of using the standard catalyst [Al(OiPr)3] in stoichiometric amounts or even in excess. Rare-earth-metal-based catalysts are capable of performing in these reactions in a truly catalytic fashion. The ceric alkoxide [Ce(OiPr)4]3 has been synthesized via silylamine elimination from Ce[N(SiHMe2)2]4 with isopropyl alcohol, its trimetallic solid-state structure has been determined by X-ray diffraction, and its performance in the MPV reduction of 4-tBu-cyclohexanone has been examined and compared to that of cerous [Ce(OCH2tBu)3]4. Spherical mesoporous silica nanoparticles with an MCM-41-type honeycomb pore symmetry, termed MSN-MCM-41 (particle size, ca. 250 nm diameter; pore size, 2.6 nm diameter), are employed for grafting the molecular precursors Ce[N(SiHMe2)2]4, [Ce(OiPr)4]3, Ce[N(SiMe3)2]3, and La[N(SiMe3)2]3 according to the methods of surface organometallic chemistry (SOMC). The MPV reductions carried out with the homogeneous and heterogeneous catalysts reveal (a) a better performance of Ce(III) in comparison to Ce(IV), (b) better performance of La[N(SiMe3)2]3?MSN-MCM-41 in comparison to Ce[N(SiMe3)2]3?MSN-MCM-41 (high sensitivity of Ce(III)-grafted materials), and (c) reusability of the grafted catalyst systems. All hybrid materials were characterized by PXRD, N2 physisorption, and 1H/13C/29Si MAS NMR and FTIR spectroscopies as well as elemental analysis.
A direct conversion of aldohexopyranose to ketohexopyranose benzyl derivatives by Meerwein-Ponndorf/Oppenauer reaction induced by air-oxidised samarium diiodide
Adinolfi, Matteo,Iadonisi, Alfonso,Mangoni, Lorenzo
, p. 5987 - 5988 (1996)
2,3,4,6-tetra-O-benzyl-D-galactopyranose and 2,3,4,6-tetra-O-benzyl-D-glucopyranose can be reduced at C-1 and oxidised at C-5 to give 1,3,4,5-tetra-O-benzyl-L-tagatopyranose and 1,3,4,5-tetra-O-benzyl-L-sorbopyranose, respectively, in good yields, through an intramolecular M-P/O reaction induced by preoxidised samarium diiodide.
Aromatic compound hydrogenation and hydrodeoxygenation method and application thereof
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Paragraph 0094-0096; 0098; 0100-0104, (2021/05/29)
The invention belongs to the technical field of medicines, and discloses an aromatic compound hydrogenation and hydrodeoxygenation method under mild conditions and application of the method in hydrogenation and hydrodeoxygenation reactions of the aromatic compounds and related mixtures. Specifically, the method comprises the following steps: contacting the aromatic compound or a mixture containing the aromatic compound with a catalyst and hydrogen with proper pressure in a solvent under a proper temperature condition, and reacting the hydrogen, the solvent and the aromatic compound under the action of the catalyst to obtain a corresponding hydrogenation product or/and a hydrodeoxygenation product without an oxygen-containing substituent group. The invention also discloses specific implementation conditions of the method and an aromatic compound structure type applicable to the method. The hydrogenation and hydrodeoxygenation reaction method used in the invention has the advantages of mild reaction conditions, high hydrodeoxygenation efficiency, wide substrate applicability, convenient post-treatment, and good laboratory and industrial application prospects.
Half-sandwich rhodium complexes with phenylene-based SCS ligands: Synthesis, characterization and catalytic activities for transfer hydrogenation of ketones
Jia, Wei-Guo,Gao, Li-Li,Zhi, Xue-Ting,Li, Xiao-Dong,Wang, Zhi-Bao,Sun, Ying
, (2020/12/30)
A series of half-sandwich rhodium complexes with tridentate phenylene-based bis(thione) (SCS) ligand have been synthesized and characterized. Both half-sandwich rhodium complexes and phenylene-based bis(thione) compounds were fully characterized by 1H and 13C NMR spectra, mass spectrometry and single-crystal X-ray diffraction method. The catalytic activities of half-sandwich rhodium complexes toward the transfer hydrogenation of ketones to their corresponding alcohols were explored using 2-propanol as hydrogen source and solvent. And the half-sandwich rhodium complexes exhibited high catalytic activity for transfer hydrogenation of ketones with a broad functional group tolerance.
Postsynthetic Modification of Half-Sandwich Ruthenium Complexes by Mechanochemical Synthesis
Jia, Wei-Guo,Zhi, Xue-Ting,Li, Xiao-Dong,Zhou, Jun-Peng,Zhong, Rui,Yu, Haibo,Lee, Richmond
, p. 4313 - 4321 (2021/05/04)
A mild and environmentally friendly method to synthesize half-sandwich ruthenium complexes through the Wittig reaction between an aldehyde-tagged half-sandwich ruthenium complex and phosphorus ylide mechanochemically is reported herein. The mechanochemical synthesis of valuable half-sandwich ruthenium complexes resulted in a fast reaction, good yield with simple workup, and the avoidance of harsh reaction conditions and organic solvents. The synthesized half-sandwich ruthenium complexes exhibited high catalytic activity for transfer hydrogenation of ketones using 2-propanol as the hydrogen source and solvent. Density functional theory was carried out to propose a mechanism for the transfer hydrogenation process. The modeling suggests the importance of the labile p-cymene ligand in modulating the reactivity of the catalyst.
Base-free transfer hydrogenation of aryl-ketones, alkyl-ketones and alkenones catalyzed by an IrIIICp* complex bearing a triazenide ligand functionalized with pyrazole
Medrano-Castillo, Layla J.,Collazo-Flores, Miguel á.,Camarena-Díaz, Juan P.,Correa-Ayala, Erick,Chávez, Daniel,Grotjahn, Douglas B.,Rheingold, Arnold L.,Miranda-Soto, Valentín,Parra-Hake, Miguel
, (2020/03/13)
An IrIIICp* complex (2) bearing a triazenide ligand functionalized with pyrazole was synthesized and fully characterized by spectroscopic methods and the structure confirmed by X-ray diffraction studies. The catalytic activity of 2 and the control complex 3, which lacks of pyrazole in its structure, was evaluated in the reduction of aryl-ketones, alkyl-ketones, α,β-unsaturated and γ,δ-unsaturated ketones. The catalytic system, using either 2 or 3, exhibited good to excellent selectivity when tested with ketones and alkenones at 90 °C in 2-propanol as hydrogen source under base-free conditions. Reactivity of 2 in 2-propanol and NaH gave a neutral metal hydride (4) while in the absence of base gave two major cationic hydrides species (5 and 6).
Synthesis and characterization of silica-coated magnetite nanoparticles modified with bis(pyrazolyl) triazine ruthenium(II) complex and the application of these nanoparticles as a highly efficient catalyst for the hydrogen transfer reduction of ketones
Mobinikhaledi, Akbar,Moghanian, Hassan,Ajerloo, Bahram,Dousti, Fatemeh
, (2019/12/24)
We present a facile and efficient method for modifying the surface of silica-coated Fe3O4 magnetic nanoparticles (MNPs) with bis(pyrazolyl) triazine ruthenium(II) complex [MNPs@BPT–Ru (II)]. Field emission-scanning electron microscopy, thermogravimetric/derivative thermogravimetry analysis, X-ray powder diffraction, Fourier-transform infrared spectroscopy, vibrating sample magnetometry, and energy-dispersive X-ray spectrometry analyses were employed for characterizing the structure of these nanoparticles. MNPs@BPT–Ru(II) nanoparticles proved to be a magnetic, reusable, and heterogeneous catalyst for the hydrogen transfer reduction of ketone derivatives. In addition, highly pure products were obtained with excellent yields in relatively short times in the presence of this catalyst. A comparison of this catalyst with those previously used for the hydrogen transfer reactions proved the uniqueness of MNPs@BPT–Ru(II) nanoparticle which is due to its inherent magnetic properties and large surface area. The presented method also had other advantages such as simple reaction conditions, eco-friendliness, high recovery ability, easy work-up, and low cost.
Selective phenol hydrogenation under mild condition over Pd catalysts supported on Al2O3 and SiO2
Li, Xinzheng,Cheng, Ling,Wang, Xingyi
, p. 1249 - 1262 (2019/02/24)
Cyclohexanone (CHONE) is the key intermediate in the manufacture of nylon-6 and nylon-66. Selective hydrogenation of phenol into CHONE was investigated over Pd/SiO2 and Pd/Al2O3. The results show that the yield of CHONE reaches 98% or more over Pd/Al2O3 and Pd/SiO2 at 333?K under atmospheric pressure in cyclohexane solvent. High activity of Pd/Al2O3 is promoted by Lewis acidity, and phenol can be converted 100% within 300?min. The hydrogenation of CHONE occurs until the conversion of phenol approaches completion. Pd/SiO2 with smaller Pd nano-particles presents higher selectivity. For polar solvent, such as ethanol and dichloromethane, the activity of Pd catalysts decreases greatly. Auxiliary experiments verify that phenol adsorbs on Pd catalysts via the formation of π–c with an aromatic ring. Increased hydrogen pressure not only promotes significantly the rates of hydrogenation, but also increases the selectivity for CHONE, especially over Pd/SiO2-1 catalyst.
A Practical and Stereoselective In Situ NHC-Cobalt Catalytic System for Hydrogenation of Ketones and Aldehydes
Zhong, Rui,Wei, Zeyuan,Zhang, Wei,Liu, Shun,Liu, Qiang
supporting information, p. 1552 - 1566 (2019/06/14)
Homogeneous catalytic hydrogenation of carbonyl groups is a synthetically useful and widely applied organic transformation. Sustainable chemistry goals require replacing conventional noble transition metal catalysts for hydrogenation by earth-abundant base metals. Herein, we report how a practical in situ catalytic system generated by easily available pincer NHC precursors, CoCl2, and a base enabled efficient and high-yielding hydrogenation of a broad range of ketones and aldehydes (over 50 examples and a maximum turnover number [TON] of 2,610). This is the first example of NHC-Co-catalyzed hydrogenation of C=O bonds using flexible pincer NHC ligands consisting of a N-H substructure. Diastereodivergent hydrogenation of substituted cyclohexanone derivatives was also realized by fine-tuning of the steric bulk of pincer NHC ligands. Additionally, a bis(NHCs)-Co complex was successfully isolated and fully characterized, and it exhibits excellent catalytic activity that equals that of the in-situ-formed catalytic system. Catalytic hydrogenation is a powerful tool for the reduction of organic compounds in both fine and bulk chemical industries. To improve sustainability, more ecofriendly, inexpensive, and earth-abundant base metals should be employed to replace the precious metals that currently dominate the development of hydrogenation catalysts. However, the majority of the base-metal catalysts that have been reported involve expensive, complex, and often air- and moisture-sensitive phosphine ligands, impeding their widespread application. From a mixture of the stable CoCl2, imidazole salts, and a base, our newly developed catalytic system that formed easily in situ enables efficient and stereoselective hydrogenation of C=O bonds. We anticipate that this easily accessible catalytic system will create opportunities for the design of practical base-metal hydrogenation catalysts. A practical in situ catalytic system generated by a mixture of easily available pincer NHC precursors, CoCl2, and a base enabled highly efficient hydrogenation of a broad range of ketones and aldehydes (over 50 examples and up to a turnover number [TON] of 2,610). Diastereodivergent hydrogenation of substituted cyclohexanone derivatives was also realized in high selectivities. Moreover, the preparation of a well-defined bis(NHCs)-Co complex via this pincer NHC ligand consisting of a N-H substructure was successful, and it exhibits equally excellent catalytic activity for the hydrogenation of C=O bonds.
