Hydrogenation Of Various Ketones Research Articles

Enantioselective Hydrogenation of Ketones Catalyzed by Chiral Cobalt Complexes Containing PNNP Ligand

AbstractNovel chiral cobalt complexes containing a PNNP‐type ligand were synthesized using a straightforward method. The structures of the cobalt complexes have been fully characterized by X‐ray crystallography, high resolution mass spectrometry (HRMS), and electron paramagnetic resonance (EPR). Using H2 as the hydrogen source, the cobalt‐catalyzed asymmetric hydrogenation of various ketones was investigated, and the corresponding chiral alcohols were afforded with up to 99 % yield and 95 % ee. To the best of our knowledge, this is the first example of a cobalt‐catalyzed enantioselective hydrogenation of ketones with molecular hydrogen.

ChemInform Abstract: Phosphine‐Free Chiral Iridium Catalysts for Asymmetric Catalytic Hydrogenation of Simple Ketones.

AbstractNovel efficient and easily accessible pyridylalkylamine mononuclear iridium complexes are synthesized and utilized in the asymmetric hydrogenation of various ketones affording the corresponding alcohols.

Enantioselective transfer hydrogenation of various ketones with novel efficient iridium(III) ferrocenyl-phosphinite catalysts

The asymmetric reduction of prochiral ketones is a pivotal reaction for the preparation of chiral alcohols which form an extremely important class of intermediates for fine chemicals and pharmaceuticals. Especially, iridium-based asymmetric reduction of ketones to enantiomerically enriched alcohols has recently attracted important attention by a number of research groups and interest in this area is growing. Therefore, a series of novel neutral mononuclear iridium(III) ferrocenyl-phosphinite complexes have been prepared and applied in the iridium(III)-catalyzed asymmetric transfer hydrogenation (ATH) of ketones to give corresponding secondary alcohols with outstanding enantioselectivities and reactivities using 2-propanol as the hydrogen source (up to 99% ee and 99% conversion). It was seen that the substituents on the backbone of the ligands resulted in a significant effect on both the activity and % enantioselectivity. Furthermore, the structural elucidation of the complexes was carried out by elemental analysis, IR and multi-nuclear NMR spectroscopic data.

Novel chiral multidentate P3N4-type ligand for asymmetric transfer hydrogenation of aromatic ketones

Novel chiral multidentate P3N4-type ligand has been synthesized and characterized by NMR and HRMS. Using i-PrOH as solvent and hydrogen source, asymmetric transfer hydrogenation of various ketones was investigated. The catalyst generated in situ from chiral multidentate aminophosphine ligand (R,R,R,R)-3 and IrCl(CO)(PPh3)2 exhibited highly catalytic activity and excellent enantioselectivity under mild conditions, achieving the corresponding chiral alcohols with up to 99% yield and 99% ee.

A 2-(2’-pyridyl)quinoline ruthenium(II) complex as an active catalyst for the transfer hydrogenation of ketones

AbstractThe ruthenium(II) complex cis-[RuCl2(PPh3)2(L1)] (1) where L1 = 2-(2’-pyridyl)quinoline was obtained in high yield from the reaction of [RuCl2(PPh3)3] with L1. The new compound was characterized by different spectroscopic methods including FT-IR, UV-Vis, NMR (1H, 31P) spectroscopy along with a mass spectrometric analysis (ESI-MS) and conductivity measurements. 31P NMR spectroscopy provided evidence that the two PPh3 ligands are orientated trans to each other in an octahedral environment. Complex (1) was tested in the transfer hydrogenation of various ketones in 2-propanol at 82 oC. The catalytic activity of (1) displayed quantitative conversions for benzophenone and 4-chloroacetophenone.

Synthesis and structures of ruthenium-NHC complexes and their catalysis in hydrogen transfer reaction.

Ruthenium complexes [Ru(L1)2(CH3CN)2](PF6)2 (1), [RuL1(CH3CN)4](PF6)2 (2) and [RuL2(CH3CN)3](PF6)2 (3) (L1= 3-methyl-1-(pyrimidine-2-yl)imidazolylidene, L2 = 1,3-bis(pyridin-2-ylmethyl)benzimidazolylidene) were obtained through a transmetallation reaction of the corresponding nickel–NHC complexes with [Ru(p-cymene)2Cl2]2 in refluxing acetonitrile solution. The crystal structures of three complexes determined by X-ray analyses show that the central Ru(II) atoms are coordinated by pyrimidine- or pyridine-functionalized N-heterocyclic carbene and acetonitrile ligands displaying the typical octahedral geometry. The reaction of [RuL1(CH3CN)4](PF6)2 with triphenylphosphine and 1,10-phenanthroline resulted in the substitution of one and two coordinated acetonitrile ligands and afforded [RuL1(PPh3)(CH3CN)3](PF6)2 (4) and [RuL1(phen)(CH3CN)2](PF6)2 (5), respectively. The molecular structures of the complexes 4 and 5 were also studied by X-ray diffraction analysis. These ruthenium complexes have proven to be efficient catalysts for transfer hydrogenation of various ketones.

The first application of C2-symmetric ferrocenyl phosphinite ligands for rhodium-catalyzed asymmetric transfer hydrogenation of various ketones

Homogeneous catalysis has been responsible for many major recent developments in synthetic organic chemistry. The combined use of organometallic and coordination chemistry has produced a number of new and powerful synthetic methods for important classes of compounds in general and for optically active substances in particular. For this aim, a new class of chiral modular C2-symmetric ferrocenyl phosphinite ligands has been prepared in good yields by using the inexpensive 1,1′-ferrocenedicarboxyaldehyde and various ferrocene based-amino alcohols as starting materials, and applied in the rhodium(I)-catalyzed asymmetric transfer hydrogenation (ATH) of aromatic ketones to give corresponding secondary alcohols with excellent enantioselectivities and reactivities using isoPrOH as the hydrogen source (up to 99% conversion and 99%ee). The substituents on the backbone of the ligands are found to exhibit a remarkable effect on both the activity and % ee. The structures of these ligands and their complexes have been elucidated by a combination of multinuclear NMR spectroscopy, IR spectroscopy and elemental analysis.

Asymmetric transfer hydrogenation of ketones catalyzed by thermoregulated ionic liquid-regulating ruthenium complexes

A sulfonated chiral diamine ligand anion-based functionalized ionic liquid has been synthesized. Then the new ionic liquid-regulating ruthenium complexes were prepared successfully and employed as efficient catalysts for the asymmetric transfer hydrogenation of various ketones. The catalysts were highly efficient for the hydrogenation of a wide range of substrates bearing different functional groups and could be separated easily from the reaction mixture by thermoregulated phase separation, which can be efficiently recycled five times without significant changes in catalytic activity and enantioselectivity.

Sodium hydroxide-catalyzed transfer hydrogenation of carbonyl compounds and nitroarenes using ethanol or isopropanol as both solvent and hydrogen donor

The development of a clean and renewable energy carrier has become a subject of high priority, and new catalytic system that involves both abundant and cheap catalysts and green solvents is highly desirable in terms of practical and sustainable chemistry. In this spirit, sodium hydroxide-catalyzed transfer hydrogenation of carbonyl compounds using ethanol as both hydrogen source and solvent is developed in this report. The process is successfully utilized in the hydrogenation of various ketones and aldehydes, and the corresponding primary and secondary alcohols are synthesized with excellent conversions. Furthermore, sodium hydroxide also smoothly promotes the transfer hydrogenation of nitroarenes providing anilines and azobenzenes. For both carbonyl compounds and nitroarenes, results in ethanol and isopropanol are compared, and a remarkable change of selectivity between these two solvents is disclosed for the NaOH-catalyzed transfer hydrogenation to nitroarenes.

A ruthenium(II) bipyridine complex containing a 4,5-diazafluorene moiety: Synthesis, characterization and its applications in transfer hydrogenation of ketones and dye sensitized solar cells

The ruthenium(II) complex [Ru(bpy)2L](PF6)2, where bpy is 2,2′-bipyridine and L is 1,5-dihydro-2-H-cyclopenta[1,2-b:5,4-b′]dipyridine-2-one, was synthesized from the reaction of cis-Ru(bpy)2Cl2·2H2O with L, and isolated as the hexafluorophosphate salt. The structure of L was unequivocally elucidated by single-crystal X-ray diffraction analysis. The new ruthenium(II) complex was thoroughly characterized by 1H and 13C NMR spectroscopy, along with FTIR, UV–Vis and LC MS/MS Triple Quadrupole Mass spectroscopy and elemental analysis. The catalytic activity of [Ru(bpy)2L](PF6)2 was tested in the transfer hydrogenation of various ketones in 2-propanol as both the solvent and hydrogen donor. The usage of [Ru(bpy)2L](PF6)2 for the formation of a dye sensitized solar cell is also presented.

The application of tunable tridendate P‐based ligands for the Ru(II)‐catalysed transfer hydrogenation of various ketones

Two novel versatile tridendate aminophosphine–phosphinite and phosphinite ligands were prepared and their trinuclear neutral ruthenium(II) dichloro complexes were found to be effective catalysts for the transfer hydrogenation of various ketones in excellent conversions up to 99% in the presence of 2‐propanol/NaOH in 0.1 M isopropanol solution. Particularly, [Ru3(PPh2OC2H4)2 N–PPh2(η6‐p‐cymene)3Cl6] acts as an excellent catalyst giving the corresponding alcohols in excellent conversion up to 99% (turnover frequency ≤ 1176 h−1). A comparison of the catalytic properties of the complexes is also discussed briefly. Furthermore, the structures of these ligands and their corresponding complexes have also been clarified using a combination of multinuclear NMR spectroscopy, infrared spectroscopy and elemental analysis. 1H–13C HETCOR or 1H–1H COSY correlation experiments were used to confirm the spectral assignments. Copyright © 2014 John Wiley & Sons, Ltd.

Ionic liquid based Ru(II)–phosphinite compounds and their catalytic use in transfer hydrogenation: X-ray structure of an ionic compound 1-chloro-3-(3-methylimidazolidin-1-yl)propan-2-ol

The compound 1-chloro-3-(3-methylimidazolidin-1-yl)propan-2-ol chloride (1) was prepared from the reaction of 1-methylimidazole with epichlorohydrine. The corresponding phosphinite ligands were synthesized by the reaction 1-chloro-3-(3-methylimidazolidin-1-yl)propan-2-ol chloride, [C7H15N2OCl]Cl with one equivalent of chlorodiphenylphosphine or chlorodicyclohexylphosphine, in anhydrous CH2Cl2 and under an inert argon atmosphere. [Ru(η6-arene)(μ-Cl)Cl]2 dimers readily react with the phosphinite ligands [(Ph2PO)–C7H14N2Cl]Cl (2) or [(Cy2PO)–C7H14N2Cl]Cl (3) at room temperature to afford the cationic derivatives [Ru((Ph2PO)–C7H14N2Cl)(η6-arene)Cl2]Cl and [Ru((Cy2PO)–C7H14N2Cl)(η6-arene)Cl2]Cl {arene: benzene (4), (5); p-cymene (6), (7)}. The structures of these ligands and their corresponding complexes have been elucidated by a combination of multinuclear NMR and IR spectroscopy, TGA/DTA and elemental analysis. The molecular structure of the ionic compound 1 was also determined by an X-ray single crystal diffraction study. Furthermore, the catalytic activity of complexes 4–7 for the transfer hydrogenation of various ketones was investigated and these complexes were found to be efficient catalysts in the transfer hydrogenation of various ketones, with excellent conversions up to 99%. Specifically, [Ru((Cy2PO)–C7H14N2Cl)(η6-benzene)Cl2]Cl (5) and [Ru((Cy2PO)–C7H14N2Cl)(η6-p-cymene)Cl2]Cl (7) act as excellent catalysts, giving the corresponding alcohols in 98–99% conversions in 5min (TOF⩽1188h−1).

ChemInform Abstract: Novel Half‐Sandwich η5‐Cp*—Rhodium(III) and η5‐Cp*—Ruthenium(II) Complexes Bearing Bis(phosphino)amine Ligands and Their Use in the Transfer Hydrogenation of Aromatic Ketones.

Two new half-sandwich η5-Cp*–rhodium(III) and η5-Cp*–ruthenium(II) complexes have been prepared from corresponding bis(phosphino)amine ligands, thiophene-2-(N,N-bis(diphenylphosphino)methylamine) or furfuryl-2-(N,N-bis(diphenylphosphino)amine). Structures of the new complexes have been elucidated by multinuclear one- and two-dimensional NMR spectroscopy, elemental analysis and IR spectroscopy. These Cp*–rhodium(III) and Cp*-ruthenium(II) complexes bearing bis(phosphino)amine ligands were successfully applied to transfer hydrogenation of various ketones by 2-propanol. Copyright © 2013 John Wiley & Sons, Ltd.

ChemInform Abstract: Asymmetric Reduction of 2,2‐Dimethyl‐6‐(2‐oxoalkyl/oxoaryl)‐1,3‐dioxin‐4‐ones and Application to the Synthesis of (+)‐Yashabushitriol.

AbstractThe asymmetric transfer hydrogenation of various ketones (I) is achieved in high enantiomeric excess using a chiral ruthenium complex catalyst.

Novel half‐sandwich η5‐Cp *–rhodium(III) and η5‐Cp *–ruthenium(II) complexes bearing bis(phosphino)amine ligands and their use in the transfer hydrogenation of aromatic ketones

Two new half‐sandwich η5‐Cp*–rhodium(III) and η5‐Cp*–ruthenium(II) complexes have been prepared from corresponding bis(phosphino)amine ligands, thiophene‐2‐(N,N‐bis(diphenylphosphino)methylamine) or furfuryl‐2‐(N,N‐bis(diphenylphosphino)amine). Structures of the new complexes have been elucidated by multinuclear one‐ and two‐dimensional NMR spectroscopy, elemental analysis and IR spectroscopy. These Cp*–rhodium(III) and Cp*‐ruthenium(II) complexes bearing bis(phosphino)amine ligands were successfully applied to transfer hydrogenation of various ketones by 2‐propanol. Copyright © 2013 John Wiley & Sons, Ltd.

Palladium, iridium and ruthenium complexes with acyclic imino-N-heterocyclic carbenes and their application in aqua-phase Suzuki–Miyaura cross-coupling reaction and transfer hydrogenation

Palladium (4a–4c), iridium (5a–5c) and ruthenium (6a–6c) complexes have been prepared by in situ transmetalation from the corresponding silver complexes of acyclic imino-functionalized imidazolium chlorides [1-(Me)-imidazolium-3-{C(p-CH(3)-Ph)=N(Ar)}]Cl (3) (Ar = 2,4,6-trimethylphenyl (3a), 2,6-diisopropylphenyl (3b) and phenyl (3c)) with [Pd(COD)Cl(2)], [Cp*IrCl(2)](2) or [Ru(p-cymene)Cl(2)](2), respectively. Iridium and ruthenium complexes, 5a[PF(6)]–5c[PF(6)], 6a[PF(6)]–6c[PF(6)], 6c[BF(4)], 6c[BPh(4)] and 6c[NTf(2)], were obtained directly from 5a–5c and 6a–6c through an anion-exchange process with KPF(6), NaBF(4), NaBPh(4) and LiNTf(2) (bis(trifluoromethylsulfonyl)imide lithium), respectively. All complexes were characterized by FT-IR, (1)H and (13)C NMR spectroscopy and elemental analysis. Crystal structures of 4a, 5a and 6c[NTf(2)], and show that five-membered chelate ring is formed in these complexes by the coordination of the carbene carbon and the imino nitrogen atom, and the latter two are cationic compounds with Cl(-) and NTf(2)(-) as counteranion respectively. The catalytic performance of Pd complexes for Suzuki-Miyaura cross-coupling reactions in pure water and Ir and Ru complexes for transfer hydrogenation of ketones and imines was tested in a wide scope of substrates. Pd complex 4b with the largest steric hinder exhibited the best performance to gain moderate to excellent yields on catalyzing Suzuki-Miyaura cross-coupling of aryl chlorides and arylboronic acids in water. While in transfer hydrogenation of various ketones, all the Ir and Ru complexes were effective with good to excellent yields. Among all these complexes, 6c[PF(6)] was found most effective, and moderate yields could be obtained even in the transfer hydrogenation of imines. Moreover, different counteranions of Ru complexes are influential on catalyzing the transfer hydrogenation, with the sequence of PF(6)(-) ≈ BF(4)(-) > BPh(4)(-) > Cl(-) > NTf(2)(-).

BF3×2CF3CH2OH (BF3×2TFE), an Efficient Superacidic Catalyst for Some Organic Synthetic Transformations.

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BF3·2CF3CH2OH (BF3·2TFE), an Efficient Superacidic Catalyst for Some Organic Synthetic Transformations

BF3.2CF3CH2OH complex was found to be a very effective superacidic catalyst comparable in acid strength to at least that of 100% anhydrous sulfuric acid for various acid-catalyzed organic transformations such as isomerizations, rearrangements, ionic hydrogenation of various ketones, and aromatics with triethylsilane and nitration of aromatics with metal nitrate. Studies of the pivalaldehyde-methyl isopropyl ketone rearrangement and the benzopinacol to phenanthrene transformation suggest that the complex has an acidity comparable to that of 100% anhydrous sulfuric acid. The structure and properties of the 1:2 boron trifluoride-trifluoroethanol complex have been further studied using NMR (1H, 13C, 19F, 11B) and DFT calculations at the B3LYP/6-311++G//B3LYP/6-31G level.

Synthesis of Ruthenium Hydride Complexes Containing beta-Aminophosphine Ligands Derived from Amino Acids and their use in the H2-Hydrogenation of Ketones and Imines

The new complexes RuHCl(PPh2CH2CHRNH2)2 and RuHCl(PPh2CH2CHRNH2)(R- binap), R=H (Pgly), R=Me [(R)-Pala] were prepared by the substitution of the PPh3 ligands in RuHCl(PPh3)3 or RuHCl(PPh3)[(R)-binap] with beta-aminophosphines derived from amino acids. The complex trans-RuHCl(Pgly)[(R)-binap] has been characterized by X-ray crystallography. The complex trans-RuHCl[(S)-Ppro]2 where (S)-Ppro is derived from proline was also prepared and characterized by X-ray crystallography. These were used as catalyst precursors in the presence of a base (KOPr-i or KOBu-t) for the hydrogenation of various ketones and imines to the respective alcohols and amines with H2 gas (1–11 atm) at room temperature. Acetophenone was hydrogenated to (S)-1-phenylethanol in low ee (up to 40%) when catalyzed by the enantiomerically pure complexes. These complexes are especially active in the hydrogenation of sterically congested and electronically deactivated ketones and imines and are selective for the hydrogenation of CO bonds over CC bonds.

Efficient heterogeneous asymmetric transfer hydrogenation of ketones using highly recyclable and accessible silica-immobilized Ru-TsDPEN catalysts.

[reaction: see text] Chiral Ru-TsDPEN [N-(p-toluenesulfonyl)-1,2-diphenylethylenediamine]-derived catalysts were first successfully immobilized onto amorphous silica gel and mesoporous silicas of MCM-41 and SBA-15 by an easily accessible approach. The catalyst immobilized on silica gel demonstrated remarkably high catalytic activities and excellent enantioselectivities (up to >99% ee) for the heterogeneous asymmetric transfer hydrogenation of various ketones. Particularly, the catalyst could be readily recovered and reused in multiple consecutive catalytic runs (up to 10 uses) with the completely maintained enantioselectivity.