cas 112653-32-4, (S)-(-)-1-(2-FURYL)ETHANOL

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Cinchona-Alkaloid-Derived NNP Ligand for Iridium-Catalyzed Asymmetric Hydrogenation of Ketones
Most ligands applied for asymmetric hydrogenation are synthesized via multistep reactions with expensive chemical reagents. Herein, a series of novel and easily accessed cinchona-alkaloid-based NNP ligands have been developed in two steps. By combining [Ir(COD)Cl]2, 39 ketones including aromatic, heteroaryl, and alkyl ketones have been hydrogenated, all affording valuable chiral alcohols with 96.0-99.9% ee. A plausible reaction mechanism was discussed by NMR, HRMS, and DFT, and an activating model involving trihydride was verified.
Zhang, Lin,Zhang, Ling,Chen, Qian,Li, Linlin,Jiang, Jian,Sun, Hao,Zhao, Chong,Yang, Yuanyong,Li, Chun
supporting information
p. 415 - 419
(2022/01/12)

Dynamic Kinetic Resolution of Alcohols by Enantioselective Silylation Enabled by Two Orthogonal Transition-Metal Catalysts
A nonenzymatic dynamic kinetic resolution of acyclic and cyclic benzylic alcohols is reported. The approach merges rapid transition-metal-catalyzed alcohol racemization and enantioselective Cu-H-catalyzed dehydrogenative Si-O coupling of alcohols and hydrosilanes. The catalytic processes are orthogonal, and the racemization catalyst does not promote any background reactions such as the racemization of the silyl ether and its unselective formation. Often-used ruthenium half-sandwich complexes are not suitable but a bifunctional ruthenium pincer complex perfectly fulfills this purpose. By this, enantioselective silylation of racemic alcohol mixtures is achieved in high yields and with good levels of enantioselection.
Oestreich, Martin,Seliger, Jan
supporting information
p. 247 - 251
(2020/10/29)

Phase Separation-Promoted Redox Deracemization of Secondary Alcohols over a Supported Dual Catalysts System
Unification of oxidation and reduction in a one-pot deracemization process has great significance in the preparation of enantioenriched organic molecules. However, the intrinsic mutual deactivation of oxidative and reductive catalysts and the extrinsic incompatible reaction conditions are unavoidable challenges in a single operation. To address these two issues, we develop a supported dual catalysts system to overcome these conflicts from incompatibility to compatibility, resulting in an efficient one-pot redox deracemization of secondary alcohols. During this transformation, the TEMPO species onto the outer surface of silica nanoparticles catalyze the oxidation of racemic alcohols to ketones, and the chiral Rh/diamine species in the nanochannels of the thermoresponsive polymer-coated hollow-shell mesoporous silica enable the asymmetric transfer hydrogenation (ATH) of ketones to chiral alcohols. To demonstrate the general feasibility, a series of orthogonal oxidation/ATH cascade reactions are compared to prove the compatible benefits in the elimination of their deactivations and the balance of the cascade directionality. As presented in this study, this redox deracemization process provides various chiral alcohols with enhanced yields and enantioselectivities relative to those from unsupported dual catalysts systems. Furthermore, the dual catalysts can be recycled continuously, making them an attractive feature in the application.
Zhao, Zhitong,Wang, Chengyi,Chen, Qipeng,Wang, Yu,Xiao, Rui,Tan, Chunxia,Liu, Guohua
p. 4055 - 4063
(2021/08/12)

Ruthenium-catalyzed hydrogenation of aromatic ketones using chiral diamine and monodentate achiral phosphine ligands
The Ru-catalyzed asymmetric hydrogenation of ketones with chiral diamine and monodentate achiral phosphine has been developed. A wide range of ketones were hydrogenated to afford the corresponding chiral secondary alcohols in good to excellent enantioselectivities (up to 98.1% ee). In addition, an appropriate mechanism for the asymmetric hydrogenation was proposed and verified by NMR spectroscopy.
Wang, Mengna,Zhang, Ling,Sun, Hao,Chen, Qian,Jiang, Jian,Li, Linlin,Zhang, Lin,Li, Li,Li, Chun
(2021/03/24)

Palladium-Catalyzed Regioselective and Diastereoselective C-Glycosylation by Allyl-Allyl Coupling
A Pd-catalyzed C-glycosylation reaction was developed by allyl-allyl coupling process using Achmatowicz rearrangement products as donors and methylcoumarins as acceptors under mild conditions. This method featured regio- and diastereoselectivities, stereo
Li, Junhao,Zheng, Nan,Duan, Xuelun,Li, Rui,Song, Wangze
supporting information
p. 846 - 850
(2020/12/13)

Arene-Immobilized Ru(II)/TsDPEN Complexes: Synthesis and Applications to the Asymmetric Transfer Hydrogenation of Ketones
The Noyori-Ikariya (arene)Ru(II)/TsDPEN precatalyst has been anchored to amorphous silica and DAVISIL through the η6-coordinated arene ligand via a straightforward synthesis and the derived systems, (arene)Ru(II)/TsDPEN@silica and (arene)Ru(II)/TsDPEN@DAVISIL, form highly efficient catalysts for the asymmetric transfer hydrogenation of a range of electron-rich and electron-poor aromatic ketones, giving good conversion and excellent ee's under mild reaction conditions. Moreover, catalyst generated in situ immediately prior to addition of substrate and hydrogen donor, by reaction of silica-supported [(arene)RuCl2]2 with (S,S)-TsDPEN, was as efficient as that generated from its preformed counterpart [(arene)Ru{(S,S)-TsDPEN}Cl]@silica. Gratifyingly, the initial TOFs (up to 1085 h?1) and ee's (96–97 %) obtained with these catalysts either rivalled or outperformed those previously reported for catalysts supported by either silica or polymer immobilized through one of the nitrogen atoms of TsDPEN. While the high ee's were also maintained during recycle studies, the conversion dropped steadily over the first three runs due to gradual leaching of the ruthenium.
Doherty, Simon,Knight, Julian G.,Alshaikh, Hind,Wilson, James,Waddell, Paul G.,Wills, Corinne,Dixon, Casey M.
supporting information
p. 226 - 235
(2020/12/31)

Abiotic reduction of ketones with silanes catalysed by carbonic anhydrase through an enzymatic zinc hydride
Enzymatic reactions through mononuclear metal hydrides are unknown in nature, despite the prevalence of such intermediates in the reactions of synthetic transition-metal catalysts. If metalloenzymes could react through abiotic intermediates like these, then the scope of enzyme-catalysed reactions would expand. Here we show that zinc-containing carbonic anhydrase enzymes catalyse hydride transfers from silanes to ketones with high enantioselectivity. We report mechanistic data providing strong evidence that the process involves a mononuclear zinc hydride. This work shows that abiotic silanes can act as reducing equivalents in an enzyme-catalysed process and that monomeric hydrides of electropositive metals, which are typically unstable in protic environments, can be catalytic intermediates in enzymatic processes. Overall, this work bridges a gap between the types of transformation in molecular catalysis and biocatalysis. [Figure not available: see fulltext.]
Ji, Pengfei,Park, Jeeyoung,Gu, Yang,Clark, Douglas S.,Hartwig, John F.
p. 312 - 318
(2021/02/26)

Synthetic Studies toward the Berkeleyacetal Core Architecture
Berkeleyacetals are structurally complex natural products that have shown potent anti-inflammatory activity. The presence of a highly dense oxygen functionality and a polycyclic ring system presents significant synthetic challenges. Herein, we report an e
Márquez-Cadena, Miguel Adrián,Zhang, Wei,Tong, Rongbiao
supporting information
p. 9227 - 9231
(2021/11/30)

Chiral amino-pyridine-phosphine tridentate ligand, manganese complex, and preparation method and application thereof
The invention discloses a chiral amino-pyridine-phosphine tridentate ligand, a manganese complex, and a preparation method and application thereof. The chiral amino-pyridine-phosphine tridentate ligand is shown as a formula II, and the manganese complex of the chiral amino-pyridine-phosphine tridentate ligand can be used for efficiently catalyzing and hydrogenating ketone compounds to prepare chiral alcohol compounds in a high enantioselectivity mode. The chiral amino-pyridine-phosphine tridentate ligand and the manganese complex are simple in synthesis process, good in stability, high in catalytic activity and mild in reaction conditions.
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Paragraph 0597-0600; 0602

(2020/07/13)

A simple and efficient asymmetric hydrogenation of heteroaromatic ketones with iridium catalyst composed of chiral diamines and achiral phosphines
An efficient iridium catalyst composed of a simple and commercially available o-methoxytriphenylphosphine and 9-Amino (9-deoxy) epi-cinchonine was applied to the asymmetric hydrogenation of heteroaromatic ketones. A range of simple heteroaromatic ketones could be hydrogenated with good to excellent enantioselectivities and high activities. In particular, thiophene ketones and furyl ketones furnished 98.6% ee with up to 2.18 × 104(1/h) TOF. This catalytic system can be of practical value.
Li, Chun,Lu, Xunhua,Wang, Mengna,Zhang, Ling,Jiang, Jian,Yan, Shunfa,Yang, Yuanyong,Zhao, Yonglong,Zhang, Lin
(2020/09/02)

Water soluble Ru (II)–p-cymene complexes of chiral aroylthiourea ligands derived from unprotected D/L-alanine as proficient catalysts for asymmetric transfer hydrogenation of ketones
The newfangled chiral aroylthiourea ligands (L1-L6) were produced from unprotected D/L-alanine and their water soluble Ru (II) organometallic catalysts (1–6) were designed from their reaction with [RuCl2(η6-p-cymene)]2. The analytical and spectral methods were used to confirm the structure of the ligands and complexes. The solid state structure of L1, 5 and 6 was confirmed by single crystal XRD. The organometallic compounds (1–6) catalyzed the asymmetric transfer hydrogenation of aromatic, heteroaromatic and bulky ketones to yield respective enantiopure secondary alcohols with admirable conversions (up to 99%) and attractive enantiomeric excesses (ee up to 98%), in presence of formic acid and triethylamine in water medium under non-inert atmospheric conditions.
Sheeba, Mani Mary,Tamizh, Manoharan Muthu,Bhuvanesh, Nattamai S.P.,Karvembu, Ramasamy
(2019/01/04)

Manganese Catalyzed Asymmetric Transfer Hydrogenation of Ketones Using Chiral Oxamide Ligands
The asymmetric transfer hydrogenation of ketones using isopropyl alcohol (IPA) as hydrogen donor in the presence of novel manganese catalysts is explored. The selective and active systems are easily generated in situ from [MnBr(CO)5] and inexpensive C2-symmeric bisoxalamide ligands. Under the optimized reaction conditions, the Mn-derived catalyst gave higher enantioselectivity compared with the related ruthenium catalyst.
Schneek?nig, Jacob,Junge, Kathrin,Beller, Matthias
supporting information
p. 503 - 507
(2019/02/26)

Asymmetric transfer hydrogenation of ketones using Ru(0) nanoparticles modified by Chiral Thiones
The catalytic asymmetric transfer hydrogenation (ATH) of acetophenone in isopropanol by Ru(0) nanoparticles (NPs) obtained by the in-situ reduction of Ru (II) half-sandwich complexes of chiral 2-oxazolidinethiones and 2-thiozolidinethiones was examined and compared with the catalytic activity of Ru(0) NPs formed in-situ by the reduction of [Ru(p-cymene)(Cl)2]2 in presence of optically active ligands such as (S)-4-isobutylthiazolidine-2-thione, (S)-4-Isopropyl-2(?2-pyridinyl)-2-oxazoline, (8S, 9R)-(?)-cinchonidine, (S)-leucinol, (S)-phenylalaninol, and (S)-leucine. Three of the best catalytic systems were then examined for ATH of thirteen aromatic ketones with different electronic and steric properties. A maximum of 24% ee was obtained using NPs generated from the Ru (II) half-sandwich complex with (S)-4-isobutylthiazolidine-2-thione in the TH of acetophenone. The NPs were characterized by TEM and DLS measurements. Kinetic studies and poisoning experiments confirmed that the reaction is catalyzed by the chiral NPs formed in-situ. Complete characterization of the complexes, including the X-ray crystallographic characterization of two complexes, was also carried out.
Din Reshi, Noor U.,Senthurpandi, Dineshchakravarthy,Samuelson, Ashoka G.
(2019/03/21)

Lutidine-Based Chiral Pincer Manganese Catalysts for Enantioselective Hydrogenation of Ketones
A series of MnI complexes containing lutidine-based chiral pincer ligands with modular and tunable structures has been developed. The complex shows unprecedentedly high activities (up to 9800 TON; TON=turnover number), broad substrate scope (81 examples), good functional-group tolerance, and excellent enantioselectivities (85–98 % ee) in the hydrogenation of various ketones. These aspects are rare in earth-abundant metal catalyzed hydrogenations. The utility of the protocol have been demonstrated in the asymmetric synthesis of a variety of key intermediates for chiral drugs. Preliminary mechanistic investigations indicate that an outer-sphere mode of substrate–catalyst interactions probably dominates the catalysis.
Zhang, Linli,Tang, Yitian,Han, Zhaobin,Ding, Kuiling
supporting information
p. 4973 - 4977
(2019/03/17)

Asymmetric Magnesium-Catalyzed Hydroboration by Metal-Ligand Cooperative Catalysis
Asymmetric catalysis with readily available, cheap, and non-toxic alkaline earth metal catalysts represents a sustainable alternative to conventional synthesis methodologies. In this context, we describe the development of a first MgII-catalyzed enantioselective hydroboration providing the products with excellent yields and enantioselectivities. NMR spectroscopy studies and DFT calculations provide insights into the reaction mechanism and the origin of the enantioselectivity which can be explained by a metal-ligand cooperative catalysis pathway involving a non-innocent ligand.
Falconnet, Alban,Magre, Marc,Maity, Bholanath,Cavallo, Luigi,Rueping, Magnus
supporting information
p. 17567 - 17571
(2019/11/13)

Manganese complex and preparation method and application thereof
The invention discloses a manganese complex taking (RC,SP)-N-5,6,7,8-tetrahydroquinoline-1-(2-diphenylphosphino)ferrocene ethyl amine as a ligand, a preparation method and application of the manganesecomplex in catalyst ketone compound asymmetric hydrogen transfer reduction preparing chiral alcohol. The manganese complex is a cheap metal chiral catalyst, the cost is low, the thermal stability isgood, and the preparation method of the manganese complex has the advantages of mild condition, short period, simple operation condition and the like. The catalyst is used for reducing the chiral alcohol for ketone hydrogen transfer, has higher catalytic activity, and a method for preparing the chiral alcohol is simple, less in environment pollution, and high in yield.
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Paragraph 0063-0066; 0069-0079

(2020/01/03)

Lipase-Induced Oxidative Furan Rearrangements
Lipase B from Candida antarctica catalyzes the oxidative ring expansion of furfuryl alcohols using aqueous hydrogen peroxide to yield functionalized pyranones under mild conditions. The method further allows for the preparation of corresponding piperidinone derivatives by enzymatic rearrangement of N-protected furfurylamines.
Blume, Fabian,Sprengart, Petra,Deska, Jan
p. 1293 - 1296
(2018/01/27)

Iridium and Rhodium Complexes Containing Enantiopure Primary Amine-Tethered N-Heterocyclic Carbenes: Synthesis, Characterization, Reactivity, and Catalytic Asymmetric Hydrogenation of Ketones
The imidazolium salt [(S,S)-tBuNC3H3NCHPhCHPhNH2]PF6, (S,S)-11·HPF6 is a precursor to the enantiopure "Kaibene" ligand, tBu-Kaibene, (S,S)-11 featuring a tert-butyl group on the N-heterocyclic carbene (NHC) ring-nitrogen atoms. It has been prepared in high yield and purity by refluxing a chiral cyclic sulfamidate with 1-tert-butylimidazole. Similarly (S,S)-12·HPF6 with a mesityl group at the imidazolium ring-nitrogen atom has been prepared in the same fashion and serves as a source of Mes-Kaibene, (S,S)-12. These bidentate Kaibene ligands feature an NHC and a primary amine separated by a chiral linker. Salts (S,S)-11·HPF6 or (S,S)-12·HPF6 react with base and AgI or CuI to give a total of four M(Kaibene)2I compounds (M = Ag or Cu). At 22 °C, the amine-functionalized imidazolium cations undergo oxidative addition to iridium(I) in [IrCl(cod)]2 (cod = 1,5-cyclooctadiene) to generate iridium(III) hydride R-Kaibene compounds [IrHCl(cod)((S,S)-11)](PF6) (17) and [IrHCl(cod)((S,S)-12)](PF6) (18), respectively, each as a mixture of six configurational isomers. In contrast, the salt (S,S)-11·HPF6 reacts with [Ir(OtBu)(cod)]2 to produce a bimetallic iridium compound with (S,S)-11 as the bridging ligand. This compound contains interesting NH···Cl and NH···Ir noncovalent intramolecular interactions. Salt (S,S)-12·HPF6 reacts with silver oxide to yield [Ag2((S,S)-12)2](PF6)2 (20). Reagent 20 serves as an efficient transmetalation reagent to deliver to each rhodium in [RhCl(cod)]2 1 equiv of (S,S)-12 as a bidentate ligand to give [Rh(cod)((S,S)-12)](PF6). In the reaction between [IrCl(cod)]2 and 20, (S,S)-12 ends up coordinated in an iridium(III) hydride complex (22) as a tridentate ligand via the NHC, NH2, and a cyclometalated phenyl group. The two iridium hydride compounds, 18 and 22, are catalysts for the hydrogenation of a range of ketones (turnover number up to 499, turnover frequency up to 249 h-1, with er (enantiomeric ratio) up to 35:65 R:S).
Wan, Kai Y.,Roelfes, Florian,Lough, Alan J.,Hahn, F. Ekkehardt,Morris, Robert H.
supporting information
p. 491 - 504
(2018/02/17)

CHIRAL METAL COMPLEX COMPOUNDS
The invention comprises novel chiral metal complex compounds of the formula (I) wherein M, PR2, R3 and R4 are outlined in the description, its stereoisomers, in the form as a neutral complex or a complex cation with a suitable counter ion. The chiral metal complex compounds can be used in asymmetric reactions, particularly in asymmetric reductions of ketones, imines or oximes.
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Page/Page column 18; 19; 20

(2018/11/10)

Piano-stool Ru(II)-benzene complexes bearing D/L-alanine derived chiral aroylthiourea ligands for asymmetric transfer hydrogenation of ketones in water
Abstract: The new water soluble chiral Ru(II)-benzene complexes of the type [RuCl 2(η6-C 6H 6) L] were obtained from the reactions between [RuCl2(η6-C6H6)]2 and the chiral aroylthiourea ligands (L) derived from unprotected D/L-alanine and characterized. The solid-state structure of representative complexes was confirmed by single crystal X-ray diffraction technique. The Ru(II)-benzene complexes catalyzed the asymmetric transfer hydrogenation (ATH) of aromatic ketones to their enantiopure secondary alcohols. The reactions were carried out in the presence of formic acid–triethylamine mixture in water, and the product alcohols were obtained with excellent conversions (up to 99%) and enantiomeric excesses (up to 99%). The scope of the catalytic system was extended to various aromatic ketones. The catalytic activity of the present water-soluble Ru-benzene complexes toward enantioselective reduction of ketones was considerably higher than that of p-cymene analogues in water. Graphical Abstract: The water-soluble chiral Ru(II)-benzene complexes were produced from the reactions between [RuCl2(η6-C6H6)]2 and the chiral aroylthiourea ligands derived from unprotected D/L-alanine. The catalytic activity of the Ru(II)-benzene complexes toward enantioselective reduction of ketones was found to be good in water medium.[Figure not available: see fulltext.].
Sheeba, Mani Mary,Bhuvanesh, Nattamai S P,Karvembu, Ramasamy
(2018/12/04)

Development of Ferrocene-Based Diamine-Phosphine-Sulfonamide Ligands for Iridium-Catalyzed Asymmetric Hydrogenation of Ketones
A series of air-stable, easily accessible tridentate ferrocene-based diamine-phosphine sulfonamide (f-diaphos) ligands were successfully developed for iridium-catalyzed asymmetric hydrogenation of ketones. The f-diaphos ligands exhibited excellent enantioselectivity and superb reactivity in Ir-catalyzed asymmetric hydrogenation of ketones (for arylalkyl ketones, (S)-selectivity, up to 99.4% ee, and 100 000 TON; for diaryl ketones, (R)-selectivity, up to 98.2% ee, and 10 000 TON). This protocol could be easily conducted on gram scale, thereby providing a chance to various drugs.
Ling, Fei,Nian, Sanfei,Chen, Jiachen,Luo, Wenjun,Wang, Ze,Lv, Yaping,Zhong, Weihui
p. 10749 - 10761
(2018/09/06)

The open d-shell enforces the active space in 3d metal catalysis: Highly enantioselective chromium(ii) pincer catalysed hydrosilylation of ketones
Bis(oxazolinyldimethylmethyl)pyrrol (PdmBox) stereodirecting ligands provided the key to the chromium(ii)-catalysed highly enantioselective hydrosilylation of ketones. A rare square planar, chiral chromium(ii) alkyl complex was found to serve as a potent precatalyst for the reduction of a broad range of aryl alkyl and dialkyl ketone derivatives. The stereoelectronic preference of the open d4 shell of chromium(ii) firmly locks the molecular catalyst in a square planar geometry giving rise to two blocked quadrants of the coordination sphere. This earth-abundant base metal catalytic platform produces the corresponding chiral alcohols in excellent isolated yields with up to 98 %ee under mild reaction conditions (-40 °C to rt) and at low catalyst loadings (as low as 0.5 mol%).
Schiwek, Christian H.,Vasilenko, Vladislav,Wadepohl, Hubert,Gade, Lutz H.
supporting information
p. 9139 - 9142
(2018/08/24)

Enantioconvergent Biocatalytic Redox Isomerization
Alcohol dehydrogenases can act as powerful catalysts in the preparation of optically pure γ-hydroxy-δ-lactones by means of an enantioconvergent dynamic redox isomerization of readily available Achmatowicz-type pyranones. Imitating the traditionally metal-
Liu, Yu-Chang,Merten, Christian,Deska, Jan
supporting information
p. 12151 - 12156
(2018/09/11)

Tridentate nitrogen phosphine ligand and complex and application thereof in asymmetric catalytic hydrogenation of ketone
The invention belongs to the field of organic and medicine synthetic chemistry, and discloses a tridentate nitrogen phosphine ligand. The tridentate nitrogen phosphine ligand has a structure shown ina formula I which is shown in the attached figure, wherein R1 is toluene sulfonyl or 2,4,6-triisopropylbenzenesulfonyl, and R2 is aryl or substituted aryl. The invention also discloses a complex of the tridentate nitrogen phosphine ligand; the complex is prepared by mixing the tridentate nitrogen phosphine ligand and a transition metal complex; the complex is used for asymmetric catalytic hydrogenation of ketone. The tridentate nitrogen phosphine ligand has the advantages that 1, the synthesizing is easy, and the chiral ligand can be prepared by only two to three reaction steps; 2, the ligandis stable, the series of ligand is not sensitive to water and oxygen, and the convenience in storage and use is realized; 3, the catalyzing effect is good, and the catalyst can be used for realizing 100% of conversion and 99% of stereo selectivity on most of suitable primers; 4, the atom economy is high, and the activity of the catalysis system is higher; for most of suitable primers, the conversion number reaches more than 10000, and the maximum conversion number reaches 200000.
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Paragraph 0119; 0120; 0121; 0122

(2018/04/03)

Scope and Mechanism on Iridium-f-Amphamide Catalyzed Asymmetric Hydrogenation of Ketones
A series of novel and easily accessed ferrocene-based amino-phosphine-sulfonamide (f-Amphamide) ligands have been developed and applied in Ir-catalyzed asymmetric hydrogenation of aryl ketones, affording the corresponding chiral secondary alcohols with excellent results (up to >99% conversion, >99% ee and TON up to 200 000). DFT calculations suggest an activating model involving an alkali cation Li+.
Liang, Zhiqin,Yang, Tilong,Gu, Guoxian,Dang, Li,Zhang, Xumu
p. 851 - 856
(2018/07/31)

Chloroperoxidase-Catalyzed Achmatowicz Rearrangements
Chloroperoxidase from Caldariomyces fumago catalyzes the selective oxidation of furfuryl alcohols in an Achmatowicz-type ring expansion. In combination with glucose oxidase as oxygen-activating biocatalyst, a purely enzymatic, aerobic protocol for the synthesis of 6-hydroxypyranone building blocks is obtained. Thanks to an only modest stereochemical bias of the oxygenating heme protein, optically active alcohols of either configuration are converted without a significant mismatch opening up opportunities for enantioselective multienzymatic cascades. Balancing the oxidase-driven aerobic activation, extended enzyme half-lives and productive conversion of poorly soluble and slowly reacting substrates can be achieved with high yields of the six-membered O-heterocycles.
Thiel, Daniel,Blume, Fabian,J?ger, Christina,Deska, Jan
p. 2717 - 2725
(2018/05/14)

Asymmetric hydrogenation of pro-chiral ketones catalyzed by chiral Ru(II)-benzene organometallic compounds containing amino acid based aroylthiourea ligands
A series of Ru(II)-benzene organometallic compounds (1–6) constructed from [RuCl2(η6-benzene)]2and chiral aroylthiourea ligands (L1-L6) obtained from D/L-phenylalanine, was fully characterized. The chiral complexes along with 2-propanol and NaOH effected the asymmetric hydrogenation of aromatic ketones at 82?°C within 8–10?h. The reduction reactions proceeded with excellent conversions and enantiomeric excesses (up to 99%).
Sheeba, M. Mary,Tamizh, M. Muthu,Farrugia,Karvembu
p. 45 - 49
(2017/01/16)

Manganese(I)-Catalyzed Enantioselective Hydrogenation of Ketones Using a Defined Chiral PNP Pincer Ligand
A new chiral manganese PNP pincer complex is described. The asymmetric hydrogenation of several prochiral ketones with molecular hydrogen in the presence of this complex proceeds under mild conditions (30–40 °C, 4 h, 30 bar H2). Besides high catalytic activity for aromatic substrates, aliphatic ketones are hydrogenated with remarkable selectivity (e.r. up to 92:8). DFT calculations support an outer sphere hydrogenation mechanism as well as the experimentally determined stereochemistry.
Garbe, Marcel,Junge, Kathrin,Walker, Svenja,Wei, Zhihong,Jiao, Haijun,Spannenberg, Anke,Bachmann, Stephan,Scalone, Michelangelo,Beller, Matthias
supporting information
p. 11237 - 11241
(2017/09/02)

NHTs Effect on the Enantioselectivity of Ru(II) Complex Catalysts Bearing a Chiral Bis(NHTs)-Substituted Imidazolyl-Oxazolinyl-Pyridine Ligand for Asymmetric Transfer Hydrogenation of Ketones
Pincer-type ruthenium(II)-NNN complex catalysts bearing a chiral bis(NHTs)-substituted imidazolyl-oxazolinyl-pyridine ligand were synthesized and structurally characterized by NMR, IR, elemental analysis, and X-ray single-crystal crystallographic determinations. The two NHTs groups substituted on the imidazolyl moiety of the chiral NNN ligand exhibited a remarkable effect on the enantioselectivity of the Ru(II)-NNN complexes for the asymmetric transfer hydrogenation (ATH) of ketones. The Ru(II)-NNN complex bearing a chiral (NHTs)2-substituted imidazolyl-(isopropyl)oxazolinyl-pyridine ligand exhibited excellent catalytic activity, reaching an enantioselectivity up to 99.9% ee for the target alcohol products.
Chai, Huining,Liu, Tingting,Yu, Zhengkun
p. 4136 - 4144
(2017/11/21)

Enantioselective reduction of aryl and hetero aryl methyl ketones using plant cell suspension cultures of Vigna radiata
Vigna radiata was investigated as whole cell catalyst for the bioreduction of aryl and heteroaryl prochiral ketones into optically active alcohols. The study indicates selective bioreduction of different substituted aryl and heteroaryl ketones (1a–12a) to their respective (S)–chiral alcohols (1b–12b) in good to high enantioselectivity (77.7–97.5%) with very good yields (73–82%). The results obtained confirm that the keto reductase has broad substrate specificity and selectivity in catalyzing both six and five-membered heteroaryl methyl ketones. The current methodology substantiates a promising and alternative green approach for the synthesis of secondary chiral alcohols of biological importance in a mild, cheap and environmentally benign process.
Santhanam, Srinath,Patil, Swati,Shanmugam, Ramu,Dronamraju V.L, Sarada,Balasundaram, Usha,Baburaj, Baskar
p. 223 - 229
(2017/06/09)

Total Synthesis of (?)-Angiopterlactone B
An enantioselective total synthesis of (?)-angiopterlactone B has been accomplished in four steps. The synthesis features a proposed biomimetic domino ring-contraction/oxa-Michael/Michael dimerization sequence, forming three new bonds, two new rings, and
Thomson, Marie I.,Nichol, Gary S.,Lawrence, Andrew L.
supporting information
p. 2199 - 2201
(2017/05/12)

Unsymmetrical Iron P-NH-P′ Catalysts for the Asymmetric Pressure Hydrogenation of Aryl Ketones
The reductive amination of α-dialkylphosphine acetaldehydes with enantiopure β-aminophosphines is a new, versatile route to unsymmetrical tridentate (pincer) ligands P-NH-P′. Four new ligands PR2CH2CH2NHCHR′CHR′′PPh2 (R=iPr, Cy, R′=Ph, CH(CH3)2, R′′=Ph, H) prepared in this way are used to make the iron(II) complexes mer-FeCl2(CO)(P-NH-P′) and mer-FeCl(H)(CO)(P-NH-P′). The hydride complex with the rigid ligand with R′=R′′=Ph is an efficient and highly enantioselective homogeneous asymmetric pressure hydrogenation (APH) catalyst. Prochiral aryl ketones are reduced under mild conditions (THF, 0.1 mol % catalyst, 1 mol % KOtBu, 5–10 bar, 50 °C) to the (S)-alcohols, usually in enantiomeric excess (ee) greater than 90 %. DFT calculations provided transition-state structures for the enantiodetermining hydride-transfer step.
Smith, Samantha A. M.,Lagaditis, Paraskevi O.,Lüpke, Anne,Lough, Alan J.,Morris, Robert H.
p. 7212 - 7216
(2017/05/31)

Use of the Trost Ligand in the Ruthenium-Catalyzed Asymmetric Hydrogenation of Ketones
The Trost ligand, (1S,2S)-1,2-diaminocyclohexane-N,N′-bis(2′-diphenylphosphinobenzoyl) (L), is reported for the first time as a ligand for the asymmetric hydrogenation (AH) of ketones. Ligand (S,S)-L was screened in the presence of several metal salts and was found to form active catalysts if combined with ruthenium sources in the presence of hydrogen and a base. Reaction optimization was performed by screening different Ru sources, solvents, and bases. Under the optimized conditions, the complex formed by the combination of (S,S)-L with RuCl3(H2O)x in the presence of Na2CO3 was able to promote the AH of several ketones at room temperature in good yields with up to 96 % ee. The reaction kinetics measured under the optimized conditions revealed the presence of a long induction period, during which the initially formed Ru species was transformed into the catalytically active complex by reaction with hydrogen. Remarkably, a ketone that is a precursor of the antiemetic drug aprepitant was hydrogenated in excellent yield with a good ee value.
Cettolin, Mattia,Puylaert, Pim,Pignataro, Luca,Hinze, Sandra,Gennari, Cesare,de Vries, Johannes G.
p. 3125 - 3130
(2017/08/29)

Mechanism-Based Enantiodivergence in Manganese Reduction Catalysis: A Chiral Pincer Complex for the Highly Enantioselective Hydroboration of Ketones
A manganese alkyl complex containing a chiral bis(oxazolinyl-methylidene)isoindoline pincer ligand is a precatalyst for a catalytic system of unprecedented activity and selectivity in the enantioselective hydroboration of ketones, thus producing preparatively useful chiral alcohols in excellent yields with up to greater than 99 % ee. It is applicable for both aryl alkyl and dialkyl ketone reduction under mild reaction conditions (TOF >450 h?1 at ?40 °C). The earth-abundant base-metal catalyst operates at very low catalyst loadings (as low as 0.1 mol %) and with a high level of functional-group tolerance. There is evidence for the existence of two distinct mechanistic pathways for manganese-catalyzed hydride transfer and their role for enantiocontrol in the selectivity-determining step is presented.
Vasilenko, Vladislav,Blasius, Clemens K.,Wadepohl, Hubert,Gade, Lutz H.
supporting information
p. 8393 - 8397
(2017/07/11)

Catalytic Asymmetric Addition of Organolithium Reagents to Aldehydes
Herein we report an efficient catalytic system for the titanium-promoted enantioselective addition of organolithium reagents to aldehydes, based on chiral Ar-BINMOL ligands. Unprecedented yields and enantioselectivities are achieved in the alkylation reactions of aliphatic aldehydes. Remarkably, methyllithium can be added to a wide variety of aromatic and aliphatic aldehydes, providing versatile chiral methyl carbinol units in a simple one-pot procedure under mild conditions and in very short reaction times.
Veguillas, Marcos,Solà, Ricard,Shaw, Luke,Maciá, Beatriz
p. 1788 - 1794
(2016/04/05)

Chiral N-heterocyclic carbene iridium catalyst for the enantioselective hydrosilane reduction of ketones
Enantioselective reduction of ketones with (EtO)2MeSiH catalyzed by an in-situ generated N-heterocyclic carbene (NHC) Ir complex at room temperature has been developed. A series of benzimidazolium salts were synthesized and screened in the asymmetric hydrosilylation reaction. As a result, propiophenone was efficiently reduced by the combined catalytic system of [IrCl(cod)]2 and NHC-Ag complex derived from N-(1-naphthalenylmethyl)-substituted benzimidazolium salt L12, affording the corresponding alcohol in 92% yield and with 92% ee. Moreover, the evaluation of an Ir catalyst precursor showed that cationic [Ir(cod)2]BF4 complex could be used. Furthermore, the introduction of a chiral hydroxyamide side arm into the benzimidazolium salt was critical for the successful design of the NHC ligand.
Manabe, Yoshiki,Shinohara, Kanako,Nakamura, Hanako,Teramoto, Hiro,Sakaguchi, Satoshi
p. 138 - 145
(2016/06/15)

Ru(II)-p-cymene complexes containing esters of chiral D/L-phenylalanine derived aroylthiourea ligands for enantioselective reduction of pro-chiral ketones
A series of new chiral aroylthiourea ligands was derived from unprotected d/l-phenylalanine: (R)/(S)-2-(3-benzoylthioureido)-3-phenylpropanoic acid (L1/L2), (R)/(S)-2-(3-(thiophene-2-carbonyl)thioureido)-3-phenylpropanoic acid (L3/L4) and (R)/(S)-2-(3-(furan-2-carbonyl)thioureido)-3-phenylpropanoic acid (L5/L6). Chiral Ru(ii) complexes (1-6) were obtained from the reactions between the chiral ligands (L1-L6) and [RuCl2(p-cymene)2]2 through in situ catalytic esterification of the ligand in the presence of methanol solvent. The ligands and complexes were characterized by analytical and spectral (1H NMR, 13C NMR, Mass, FT-IR, electronic) techniques. The molecular structure of the ligand L1 showed the presence of an unprotected acid group and that of the representative complexes confirmed the conversion of acid to ester. The X-ray structure of two of the complexes (3 and 6) revealed the sulfur only monodentate coordination of the aroylthiourea ligands. All the chiral complexes turned out to be efficient catalysts for the enantioselective reduction of aromatic pro-chiral ketones in the presence of 2-propanol and NaOH to produce chiral alcohols in excellent conversions (up to 99%) and enantiomeric excesses (up to 99%) within 10-12 h.
Sheeba, Mani Mary,Tamizh, Manoharan Muthu,Babu, Sundaram Ganesh,Bhuvanesh, Nattamai S. P.,Karvembu, Ramasamy
p. 68494 - 68503
(2016/08/02)

Aqueous biphasic iron-catalyzed asymmetric transfer hydrogenation of aromatic ketones
For the first time, an iron(ii) catalyst is used in the biphasic asymmetric transfer hydrogenation (ATH) of ketones to enantioenriched alcohols employing water and potassium formate as the proton and hydride source, respectively. The precatalyst [FeCl(CO)(P-NH-N-P)]BF4 (P-NH-N-P = (S,S)-PPh2CH2CH2NHCHPhCHPhNCHCH2PPh2) in the organic phase with the substrate is activated by base to produce a system that rivals the best ruthenium biphasic ATH catalysts in activity but not enantioselectivity. Biorenewable 2-methyltetrahydrofuran as a cosolvent and biodegradable TWEEN80 as a surfactant were added to the reaction mixture to greatly decrease the mass-transfer limitations caused by the biphasic reaction mixture. The enantioselectivity of the reduction was as high as 76% depending on the substitution pattern of the arylketone employed. NMR studies verified the formation of an iron hydride [FeH(CO)(PPh2CH2CH2NHCHPhCHPhNCHCHPPh2)] intermediate as was observed in our 2-propanol-based ATH studies.
Demmans,Ko,Morris
p. 88580 - 88587
(2016/09/28)

Synthesis of aminomethyl quinazoline based ruthenium (II) complex and its application in asymmetric transfer hydrogenation under mild conditions
The new chiral aminomethyl quinazoline (amq) type ligand derived from L-phenylalanine was synthesized and coordinated with [RuCl2(PPh3)dppb] to obtain ruthenium(II) complex. This catalyst displayed considerable reactivity (up to 97% ee and 99% conversion) in the asymmetric transfer hydrogenation of ketones using 2-propanol as a hydrogen source in the presence of NaOiPr.
Agac, Ahmet,Karakaya, Idris,Sahin, Irfan,Emir, Sedat,Karabuga, Semistan,Ulukanli, Sabri
p. 189 - 193
(2016/07/25)

Chiral ferrocenyl tridentate ligands and its preparation method for catalytic asymmetric hydrogenation and the application of the catalyst in the reaction
The invention discloses a ferrocene tridentate ligand which has planar chirality and carbon chirality and is shown in a structure general formula (I). In the formula (I), R1 is aryl or C1-C6 alkyl, R2 is C1-C6 alkyl, n is equal to 1-4, or R2 does not exist. The ferrocene tridentate ligand is synthesized by adopting the steps of carrying out coupling and acetic anhydride esterifying with R12PCl after lithiating by sec-butyl lithium by using chiral Ugi's amine as a raw material, and finally generating nucleophilic substitution with aminomethyl pyridine or substituted aminomethyl pyridine. The chiral ferrocene tridentate ligand disclosed by the invention has high catalysis activity; and an Ir complex catalyst has excellent three-dimensional selectivity and high catalysis activity when being used in asymmetric hydrogenation of prochiral ketone.
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Paragraph 0049; 0050; 0051; 0052; 0053

(2017/01/26)

IRON(II) CATALYSTS CONTAINING TRIDENTATE PNP LIGANDS, THEIR SYNTHESIS, AND USE THEREOF
The application describes catalytic materials for hydrogenation or asymmetric hydrogenation. In particular, the application describes iron(ll) complexes containing tridentate diphosphine PNP ligands useful for catalytic hydrogenation.
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Paragraph 0263

(2016/11/28)

Stereoselective reduction of aromatic ketones by a new ketoreductase from Pichia glucozyma
A new NADPH-dependent benzil reductase (KRED1-Pglu) was identified from the genome of the non-conventional yeast Pichia glucozyma CBS 5766 and overexpressed in E. coli. The new protein was characterised and reaction parameters were optimised for the enantioselective reduction of benzil to (S)-benzoin. A thorough study of the substrate range of KRED1-Pglu was conducted; in contrast to most other known ketoreductases, KRED1-Pglu prefers space-demanding substrates, which are often converted with high stereoselectivity. A molecular modelling study was carried out for understanding the structural determinants involved in the stereorecognition experimentally observed and unpredictable on the basis of steric properties of the substrates. As a result, a new useful catalyst was identified, enabling the enantioselective preparation of different aromatic alcohols and hydroxyketones.
Contente, Martina Letizia,Serra, Immacolata,Brambilla, Marta,Eberini, Ivano,Gianazza, Elisabetta,De Vitis, Valerio,Molinari, Francesco,Zambelli, Paolo,Romano, Diego
p. 193 - 201
(2016/01/09)

Seawater-Based Biocatalytic Strategy: Stereoselective Reductions of Ketones with Marine Yeasts
The large consumption of freshwater in fermentations and bio-transformations is a matter of concern for the sustainability of many bio-processes. The use of seawater to perform bio-processes is a sustainable alternative. In this work, we used marine yeasts from deep-sub-seafloor sediments grown in seawater as bio-catalysts to perform the stereoselective reduction of different ketones, and the bio-transformations were accomplished in seawater as well. Strains of Meyerozyma guilliermondii and Rhodotorula mucilaginosa were able to reduce different aromatic ketones with high molar conversions and moderate-to-high enantioselectivity with no significant differences between bio-catalysis performed in seawater and freshwater. Finally, the selected marine yeasts were used for the reduction of key intermediates in seawater for the synthesis of molecules of pharmaceutical interest (desogestrel, norgestrel, gestodene, pramipexole).
Serra, Immacolata,Guidi, Benedetta,Burgaud, Gaetan,Contente, Martina L.,Ferraboschi, Patrizia,Pinto, Andrea,Compagno, Concetta,Molinari, Francesco,Romano, Diego
p. 3254 - 3260
(2016/10/24)

De novo asymmetric synthesis and biological analysis of the daumone pheromones in Caenorhabditis elegans and in the soybean cyst nematode Heterodera glycines
The de novo asymmetric total syntheses of daumone 1, daumone 3 along with 5 new analogs are described. The key steps of our approach are: the diastereoselective palladium catalyzed glycosylation reaction; the Noyori reduction of 2-acetylfuran and an ynone
Guo, Haibing,La Clair, James J.,Masler, Edward P.,O'Doherty, George A.,Xing, Yalan
supporting information
p. 2280 - 2286
(2016/04/19)

Chemoenzymatic Total Synthesis of (+)- & (?)-cis-Osmundalactone
Both optical antipodes of the cis-isomers of osmundalactone, a hydroxypyranone natural product and core structure of the angiopterlactones, have been synthesized from acetylfuran in only three steps through a redox cascade utilizing oxidoreductases and tr
Blume, Fabian,Liu, Yu-Chang,Thiel, Daniel,Deska, Jan
p. 280 - 284
(2016/12/16)

Transfer hydrogenation reactions catalyzed by chiral half-sandwich Ruthenium complexes derived from Proline
Chiral ruthenium half-sandwich complexes were prepared using a chelating diamine made from proline with a phenyl, ethyl, or benzyl group, instead of hydrogen on one of the coordinating arms. Three of these complexes were obtained as single diastereoisomers and their configuration identified by X-ray crystallography. The complexes are recyclable catalysts for the reduction of ketones to chiral alcohols in water. A ruthenium hydride species is identified as the active species by NMR spectroscopy and isotopic labelling experiments. Maximum enantio-selectivity was attained when a phenyl group was directly attached to the primary amine on the diamine ligand derived from proline. [Figure not available: see fulltext.]
Pandia Kumar, Arun Kumar,Samuelson, Ashoka G
p. 1405 - 1415
(2016/09/19)

Tuning lipase-catalysed kinetic resolution of 2-substituted thiophenes and furans: A scalable chemoenzymatic route to masked γ-bis-oxo-alcohols
The demand for greener and applicable approaches aiming at the synthesis of optically active compounds as single enantiomers has seen a significant growth worldwide. Since most of the chemically synthesized compounds are produced as racemates their kinetic resolution has been of great interest. For this purpose a number of chemo-enzymatic approaches were proposed. One of such approaches, the use of isolated lipases, is a well-established alternative. Herein we report the kinetic resolutions of 2-Substituted five-membered heteroaromatic rings. By optimizing the reaction conditions it was possible to produce (2-hydroxy)-2-substituted furans and thiophenes in high enantiomeric ratio (E > 200). Thus, racemic mixtures of compounds with slight structural differences were resolved. The current chemo-enzymatic strategy has been applied to a scalable approach leading to the formation of the enantiopure (S)-2i a well-known building block used for the synthesis of bioactive natural compounds.
Ferreira, Dartagnan S.P.,Ferreira, Jeiely G.,Filho, Everaldo F.S.,Princival, Jefferson L.
p. 37 - 45
(2016/02/18)

Mechanochemical Enzymatic Kinetic Resolution of Secondary Alcohols under Ball-Milling Conditions
Mechanosynthesis is a valuable technique, offering attractive alternatives for the preparation of organic, inorganic, and organometallic products. Surprisingly, mechanochemical enzymatic transformations have only scarcely been studied until now. Here, we demonstrate the use of lipase B from Candida antarctica (CALB) in acylative kinetic resolutions of secondary alcohols in mixer and planetary mills. Despite the mechanical stress caused by the high-speed ball milling, the biocatalyst proved highly effective, stable, and, in part, recyclable under the applied mechanochemical conditions. Best milling practice: The compatibility of lipase B from Candida antarctica (CALB) in acylative kinetic resolutions of secondary alcohols in mixer and planetary mills has been explored. Despite the mechanical stress caused by the high-speed ball milling, the biocatalyst was found to be very effective, stable, and, in part, recyclable under the applied mechanochemical conditions.
Hernández, José G.,Frings, Marcus,Bolm, Carsten
p. 1769 - 1772
(2016/06/01)

Enantioselective addition of organozinc reagents to carbonyl compounds catalyzed by a camphor derived chiral γ-amino thiol ligand
In this article, the design and synthesis of the chiral camphor derived γ-amino thiol ligand 17 and its application in catalytic enantioselective carbon-carbon forming reactions through the addition of organozinc reagents to carbonyl compounds is described. The catalytic activity and enantioselectivity of ligand 17 is demonstrated in the enantioselective addition of various organozinc reagents to aldehydes and ketoesters, offering the corresponding alcohols in high yields and enantioselectivities. The role of the mercapto group in the highly enantioselective 1,2-addition reaction of organozincs to aldehyde is also discussed.
Wu, Hsyueh-Liang,Wu, Ping-Yu,Cheng, Ying-Ni,Uang, Biing-Jiun
p. 2656 - 2665
(2016/05/10)

Asymmetric reduction of ketones by biocatalysis using clementine mandarin (Citrus reticulata) fruit grown in annaba or by ruthenium catalysis for access to both enantiomers
Biocatalytic reduction of prochiral ketones using freshly ripened clementine mandarin (Citrus reticulata) in aqueous medium is reported. High enantioselectivities were observed, especially for the bioreduction of indanone 3, tetralone 4, and thiochromanone 5 with respectively 95%, 99%, and 86% enantiomeric excess (ee). Enantioselective bio- and metalcatalyzed reactions were compared. Chiral ruthenium catalysts afforded good asymmetric inductions (>75% ee) in most cases, enantiomeric excesses depending on the nature of substrate and ligand. N-aminoindanol prolinamide L3 was revealed as the best ligand for most ketones. Interestingly, for several substrates both enantiomers could be obtained using either Citrus reticulata or ruthenium complex.
Bennamane, Manhel,Zeror, Saoussen,Aribi-Zouioueche, Louisa
p. 205 - 210
(2015/03/18)