Synthesis of chiral 1,2-diamine immobilized on polystyrene and its application to asymmetric hydrogenation of aromatic ketones
TL;DR: In this article, a polymeric chiral complex was used as a catalyst of asymmetric hydrogenation of aromatic ketones to yield the corresponding secondary alcohols in quantitative conversion with high level of enantioselectivity.
Abstract: A novel chiral 1,2-diamine monomer (S,S)-12 has been synthesized and copolymerized with styrene to give cross-linked polymer. After deprotection of the tert-butoxycarbonyl groups, polymer-supported chiral 1,2-diamine (S,S)-P was obtained. The primary 1,2-diamine moieties on the polymer have been allowed to form the complex with RuCl2/(S)-BINAP. The polymeric chiral complex was used as a catalyst of asymmetric hydrogenation of aromatic ketones to yield the corresponding secondary alcohols in quantitative conversion with high level of enantioselectivity. The polymeric catalyst was recycled several times without any loss of the catalytic activity.
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TL;DR: In this paper, two types of ligand are considered: BINAP and BOX, and some of them appear to give a higher performance than others, such as the polymer with ligand in the main chain and with rigid spacer in case of the binAP and the ligand grafted on silica particles in the case of BOX.
Abstract: Industrial developments of asymmetric catalysis are slowed down by cost and toxicity of the soluble transition metal complexes which are used as catalysts. This problem could be solved by using homogeneous supported catalysis among other technologies. The article analyzes recent results obtained in the fields of catalysis using transition metal complexes grafted on organic or inorganic materials. Two types of ligand are considered: BINAP and BOX. In these two cases several approaches are still under investigations and some of them appear to give a higher performance, such as the polymer with ligand in the main chain and with rigid spacer in case of the BINAP and the ligand grafted on silica particles in the case of BOX.
30 citations
TL;DR: An enantiomerically pure chiral monomer (S, S ) -2 was prepared and copolymerized with styrene and four different crosslinkers to produce four distinct microgel-supported chiral TsDPEN derivatives as mentioned in this paper.
Abstract: An enantiomerically pure chiral monomer ( S , S ) -2 was prepared and copolymerized with styrene and four different cross-linkers to produce four distinct microgel-supported chiral TsDPEN derivatives. These chiral copolymers were allowed to form complexes with [RuCl 2 (cymene)] 2 and the resulting homogeneous catalysts were applied in asymmetric hydrogenation reactions of aromatic ketones to give enantioenriched secondary alcohols in quantitative yield. These polymeric catalysts can be easily separated from the reaction mixture and recycled several times without a significant loss in catalytic activity.
9 citations
TL;DR: In this article, a polymer-supported chiral 1,2-diamine was used for asymmetric hydrogenation of aromatic ketones to afford the corresponding secondary alcohols in quantitative yields with high enantioselectivities.
Abstract: Polymer-supported chiral 1,2-diamines were prepared by two methods including (1) chemical modification of a Merrifield-type resin with a chiral 1,2-diamine and (2) polymerization of a 1,2-diamine monomer. The polymeric complex formed by the polymer-supported 1,2-diamine and RuCl2-BINAP was used for the asymmetric hydrogenation of aromatic ketones to afford the corresponding secondary alcohols in quantitative yields with high enantioselectivities up to 99% ee in the asymmetric hydrogenation. The polymeric catalyst could be reused many times without any loss of activity or enantioselectivity.
9 citations
TL;DR: In this article, Butyloxycarbonyl (Boc) protected chiral 1,2-diamine polymers were copolymerized with achiral vinyl monomers such as styrene, methacrylates, acrylsates, methacellates, and acrylamide.
8 citations
03 Jan 2017
TL;DR: In this paper, the authors highlight the platinum nanoparticles incorporated chiral polyamide for asymmetric hydrogenation of carbonyl group and demonstrate that the catalytically active single atom nanoparticles have preferentially Pt (111) planes and exhibit excellent selectivity up to 10 cycles.
Abstract: The present study highlights platinum nanoparticles incorporated chiral polyamide for asymmetric hydrogenation of carbonyl group. Chiral polyamides are synthesized from chiral monomers, camphoric dichloride and achiral diamine monomers by interfacial condensation reaction. This chiral polyamide supports have helical structure with molecular chirality. The polyamide helices provide chiral environment to platinum nanoparticles that transfer to substrate during catalytic hydrogenation. The chemical and optical selectivity increases with dispersion of platinum nanoparticles on chiral polyamide which act like isolated single atomic catalytic centers. The distribution of nanoparticles depends on spacer used in amine monomer unit. The catalytically active single atom nanoparticles have preferentially Pt (111) planes and exhibit excellent selectivity up to 10 cycles (TOF > 5400 h−1 and > 99.9% ee) in asymmetric hydrogenation reaction of ethyl 2-oxo-4-phenylbutanoate under solvent free condition.
7 citations
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3,181 citations
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01 Jan 1999
TL;DR: Ohkuma et al. as mentioned in this paper proposed an asymmetric Dihydroxylation process for carbon-Carbon double bonds and showed that it can be used for allylation of C=O.
Abstract: 5.2. R.L. Halterman: Hydrogenation of Non-Functionalized Carbon-Carbon Double Bonds .- 6.4. T. Ohkuma, R. Noyori: Hydroboration of Carbonyl Groups .- 20.1. A. Bayer: Latest Developments in the Asymmetric Dihydroxylation Process .- 20.2. A. Bayer: Aminohydroxylation of Carbon-Carbon Double Bonds .- 24. J.-F. Paquin, M. Lautens: Allylic Substitution Reactions .- 27. A. Yanagisawa: Allylation of C=O .- 31.1. K. Tomioka: Conjugate Addition of Organometallics to Activated Olefins .- 34.2. A. Yanagisawa: Protonation of Enolates
2,497 citations
TL;DR: The newly devised [RuCl(2)(phosphane)(2)(1,2-diamine)] complexes are excellent precatalysts for homogeneous hydrogenation of simple ketones which lack any functionality capable of interacting with the metal center.
Abstract: Hydrogenation is a core technology in chemical synthesis. High rates and selectivities are attainable only by the coordination of structurally well-designed catalysts and suitable reaction conditions. The newly devised [RuCl(2)(phosphane)(2)(1,2-diamine)] complexes are excellent precatalysts for homogeneous hydrogenation of simple ketones which lack any functionality capable of interacting with the metal center. This catalyst system allows for the preferential reduction of a C=O function over a coexisting C=C linkage in a 2-propanol solution containing an alkaline base. The hydrogenation tolerates many substituents including F, Cl, Br, I, CF(3), OCH(3), OCH(2)C(6)H(5), COOCH(CH(3))(2), NO(2), NH(2), and NRCOR as well as various electron-rich and -deficient heterocycles. Furthermore, stereoselectivity is easily controlled by the electronic and steric properties (bulkiness and chirality) of the ligands as well as the reaction conditions. Diastereoselectivities observed in the catalytic hydrogenation of cyclic and acyclic ketones with the standard triphenylphosphane/ethylenediamine combination compare well with the best conventional hydride reductions. The use of appropriate chiral diphosphanes, particularly BINAP compounds, and chiral diamines results in rapid and productive asymmetric hydrogenation of a range of aromatic and heteroaromatic ketones and gives a consistently high enantioselectivity. Certain amino and alkoxy ketones can be used as substrates. Cyclic and acyclic alpha,beta-unsaturated ketones can be converted into chiral allyl alcohols of high enantiomeric purity. Hydrogenation of configurationally labile ketones allows for the dynamic kinetic discrimination of diastereomers, epimers, and enantiomers. This new method shows promise in the practical synthesis of a wide variety of chiral alcohols from achiral and chiral ketone substrates. Its versatility is manifested by the asymmetric synthesis of some biologically significant chiral compounds. The high rate and carbonyl selectivity are based on nonclassical metal-ligand bifunctional catalysis involving an 18-electron amino ruthenium hydride complex and a 16-electron amido ruthenium species.
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