116-02-9Relevant academic research and scientific papers
New P-chirogenic tert.-butyl-xantphos ligands and their application in asymmetric hydrogenation and alkylation
B?rner, Armin,Gandelman, Mark,Holz, Jens,Spannenberg, Anke,Wenzel, Gudrun
, (2020)
The synthesis of a broad library of new P-chirogenic Xantphos ligands is reported. A special feature is 2,7-di-tert.-butyl substituents in the backbone which requires the modification of the original synthetic approach. In comparison to related ligands reported formerly the substitution has a considerable influence on the results (yield and % e.e.) of metal catalyzed reactions, e.g. asymmetric rhodium catalyzed hydrogenation of isophorone and the palladium catalyzed alkylation, respectively.
Reduction of ketones to corresponding alcohols with magnesium metal in absolute alcohols
Kim, Ji Young,Kim, Hak Do,Seo, Min Jung,Kim, Hyoung Rae,No, Zaesung,Ha, Deok-Chan,Lee, Ge Hyeong
, p. 9 - 12 (2006)
Various aliphatic and aromatic ketones are treated with 10 equiv of magnesium metal in absolute methanol or ethanol to afford corresponding alcohols in very high yields at room temperature within 12 h.
SYNTHESIS, CHARACTERIZATION AND PROPERTIES OF SOME ORGANOZINC HYDRIDE COMPLEXES
Koning, A. J. De,Boersma, J.,Kerk, G. J. M. Van Der
, p. 1 - 12 (1980)
The synthesis and characterization of the monopyridine complexes of ethylzinc hydride and phenylzinc hydride are described.On treatment with TMED these complexes are converted into R2Zn3H4.TMED species through a combination of ligand-exchange and disproportionation.The formation of organozinc hydrides from ω-functionally-substituted diorganozinc compounds is only successful when the intramolecular coordination in these starting materials is weak and easily broken by pyridine.The results of these investigations are used as a basis for a discussion of the factors governing the formation of stable organozinc hydrides.The RZnH.py complexes easily reduce ketones and aldehydes, but no unusual stereoselectivity was observed in the reduction of substituted cyclohexanones.EtZnH.py reacts with an excess of pyridine with formation of the bis pyridine complex of ethyl(1,4-dihydro-1-pyridyl)zinc, a soluble compound, which is monomeric in benzene.The corresponding phenylzinc complex, however, cannot be isolated; disproportionation to Ph2Zn.2py and the bis pyridine complex of bis(1,4-dihydro-1-pyridyl)zinc occurs.
Photochemical ring opening of cyclopropyl ketones induced by electron transfer
Cossy, Janine,Furet, Nathalie
, p. 8107 - 8110 (1993)
Irradiation of substituted bicyclo[n.1.0]alkan-2-ones at 254 nm in the presence of triethylamine and lithium perchlorate (LiClO4) can lead to cyclopropane ring opening with cleavage of the C(1)-C(n +2) (ring enlargement) or C(1)-C(n+3) bonds.
Cu/SiO2-catalyzed hydrogenation of cyclohexanones under very mild conditions
Ravasio, Nicoletta,Psaro, Rinaldo,Zaccheria, Federica
, p. 3943 - 3945 (2002)
Unsubstituted and alkyl-substituted cyclohexanones, including 3-oxo-steroids, can be easily hydrogenated to the corresponding alcohols at 1 atm of H2 and 60-90°C over a 8% Cu/SiO2 non-toxic, reusable catalyst with excellent selectivity.
Preparation and application of surface activated Si-MCM-41 and SBA-16 as reusable supports for reduction of cyclic ketones with preferential stereoselectivity
Chaudhuri, Haribandhu,Dash, Subhajit,Sarkar, Ashis
, p. 99444 - 99454 (2016)
An efficient and benign procedure for the reduction of a few cyclic ketones adsorbed on the activated surface of calcined Si-MCM-41 and calcined SBA-16 using NaBH4 as the reducing agent with ethanol as the medium resulted in the formation of two epimeric alcohols. After synthesis, these calcined materials were treated with concentrated HCl to activate surface silanol groups. Various instrumental techniques like FTIR, XRD, N2 sorption isotherms, FESEM, TEM and XPS were carried out to examine the pre and post activated surface of the used supports. Five cyclic ketones were reduced. Reduction of 4-tert-butylcyclohexanone yielded only trans-4-tert-butylcyclohexanol. Moreover, exclusive formation of cis-3-methylcyclohexanol (equatorial -OH) was also observed. This work offers several advantages such as a simple operational procedure, short reaction time, and high yield of the product, along with maintaining the materials' diversity. This is due to the presence of the activated silanol groups of these materials, which cause nucleophilic activation of the carbonyl group of ketones leading to faster reaction rates. Beside this, these supports can be regenerated well from the reaction mixture using a calcination treatment followed by concentrated HCl, and reused several times without causing any serious malformation in the activated surfaces. Finally, this work opens up a new direction of research for the fabrication of solid reusable supports in the reduction of cyclic ketones.
Heterogeneous Hydroxyl-Directed Hydrogenation: Control of Diastereoselectivity through Bimetallic Surface Composition
Shumski, Alexander J.,Swann, William A.,Escorcia, Nicole J.,Li, Christina W.
, p. 6128 - 6134 (2021/05/29)
Directed hydrogenation, in which product selectivity is dictated by the binding of an ancillary directing group on the substrate to the catalyst, is typically catalyzed by homogeneous Rh and Ir complexes. No heterogeneous catalyst has been able to achieve equivalently high directivity due to a lack of control over substrate binding orientation at the catalyst surface. In this work, we demonstrate that Pd-Cu bimetallic nanoparticles with both Pd and Cu atoms distributed across the surface are capable of high conversion and diastereoselectivity in the hydroxyl-directed hydrogenation reaction of terpinen-4-ol. We postulate that the OH directing group adsorbs to the more oxophilic Cu atom while the olefin and hydrogen bind to adjacent Pd atoms, thus enabling selective delivery of hydrogen to the olefin from the same face as the directing group with a 16:1 diastereomeric ratio.
Study on the selective hydrogenation of isophorone
Xu, Lei,Sun, Shaoyin,Zhang, Xing,Gao, Haofei,Wang, Wei
, p. 4465 - 4471 (2021/02/03)
3,3,5-Trimethylcyclohexanone (TMCH) is an important pharmaceutical intermediate and organic solvent, which has important industrial significance. The selective hydrogenation of isophorone was studied over noble metal (Pd/C, Pt/C, Ir/C, Ru/C, Pd/SiO2, Pt/SiO2, Ir/SiO2, Ru/SiO2), and non-noble metal (RANEY Ni, RANEY Co, RANEY Cu, RANEY Fe, Ni/SiO2, Co/SiO2, Cu/SiO2, Fe/SiO2) catalysts and using solvent-free and solvent based synthesis. The results show that the solvent has an important effect on the selectivity of TMCH. The selective hydrogenation of isophorone to TMCH can be influenced by the tetrahydrofuran solvent. The conversion of isophorone is 100%, and the yield of 3,3,5-trimethylcyclohexanone is 98.1% under RANEY Ni and THF. The method was applied to the selective hydrogenation of isopropylidene acetone, benzylidene acetone and 6-methyl-5-ene-2-heptanone. The structures of the hydrogenation product target (4-methylpentan-2-one, 4-benzylbutan-2-one and 6-methyl-heptane-2-one) were characterized using 1H-NMR and 13C-NMR. The yields of 4-methylpentan-2-one, 4-benzylbutan-2-one and 6-methyl-heptane-2-one were 97.2%, 98.5% and 98.2%, respectively. The production cost can be reduced by using RANEY metal instead of noble metal palladium. This method has good application prospects. This journal is
P-CHIRAL PHOSPHINE LIGANDS AND USE THEREOF FOR ASYMMETRIC SYNTHESIS
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Paragraph 0920-0923, (2019/07/23)
The present invention relates to chiral compounds with two optically active phosphorus atoms, chiral transition metal catalysts which comprise these compounds as ligands, a process for preparing the P-chiral compounds and processes for asymmetric synthesis using the chiral transition metal catalysts. The present invention specifically relates to a process for preparing an optically active carbonyl compound by asymmetric hydrogenation of a prochiral α,β-unsaturated carbonyl compound with hydrogen in the presence of an optically active transition metal catalyst according to the invention. Yet more specifically, the present invention relates to a process for the asymmetric hydrogenation of citral, and also a process for preparing optically active menthol.
Pd/C-Al-water facilitated selective reduction of a broad variety of functional groups
Sch?fer,Ellstrom,Cho,T?r?k
, p. 1230 - 1234 (2017/03/20)
The chemoselective reduction of a broad variety of functional groups by a Pd/C-Al-H2O system is described. The reduction is based on the reaction of Al with the solvent water that in situ produces hydrogen that is utilized by the supported Pd catalyst toward the hydrogenation of the target functional groups. The hydrogenations are carried out under mild conditions and provided the products in high yields and selectivity. The reduction system appeared to be effective for a broad range of functional groups, including C-C, C-N, C-O and N-O multiple bonds, aromatic rings, hydrogenolysis of C-O, C-N and C-Halogen bonds. The appropriate selection of the reaction conditions allowed the selective preparation of different products from the same substrate. The simplicity, cost, tunability and the environmentally benign character of the catalytic system offer numerous advantages over the currently available methods.
