cas 63163-08-6, (S)-(-)-Methylsuccinic acid dimethyl ester

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Using Data Science To Guide Aryl Bromide Substrate Scope Analysis in a Ni/Photoredox-Catalyzed Cross-Coupling with Acetals as Alcohol-Derived Radical Sources
Ni/photoredox catalysis has emerged as a powerful platform for C(sp2)–C(sp3) bond formation. While many of these methods typically employ aryl bromides as the C(sp2) coupling partner, a variety of aliphatic radical sources have been investigated. In principle, these reactions enable access to the same product scaffolds, but it can be hard to discern which method to employ because nonstandardized sets of aryl bromides are used in scope evaluation. Herein, we report a Ni/photoredox-catalyzed (deutero)methylation and alkylation of aryl halides where benzaldehyde di(alkyl) acetals serve as alcohol-derived radical sources. Reaction development, mechanistic studies, and late-stage derivatization of a biologically relevant aryl chloride, fenofibrate, are presented. Then, we describe the integration of data science techniques, including DFT featurization, dimensionality reduction, and hierarchical clustering, to delineate a diverse and succinct collection of aryl bromides that is representative of the chemical space of the substrate class. By superimposing scope examples from published Ni/photoredox methods on this same chemical space, we identify areas of sparse coverage and high versus low average yields, enabling comparisons between prior art and this new method. Additionally, we demonstrate that the systematically selected scope of aryl bromides can be used to quantify population-wide reactivity trends and reveal sources of possible functional group incompatibility with supervised machine learning.
Doyle, Abigail G.,Gandhi, Shivaani S.,Jiang, Shutian,Kariofillis, Stavros K.,Martinez Alvarado, Jesus I.,?urański, Andrzej M.
supporting information
p. 1045 - 1055
(2022/01/19)

Chiral phosphine-phosphoramidite ester ligand as well as preparation method and application thereof
The invention provides a method for preparing a phosphine-phosphoramidite ester ligand from a chiral beta-aminophosphine intermediate and an application of the phosphine-phosphoramidite ester ligand in an asymmetric reaction. Chiral N-(2-(phosphoryl)-1-phenethyl) amide is prepared from the chiral beta-aminophosphine intermediate through an asymmetric hydrogenation reaction of (Z)-(alpha-aryl-beta-phosphoryl) alkenyl amide, and then hydrolysis reduction. The preparation method comprises the following steps: dissolving newly-prepared chlorinated phosphite in toluene, adding a solution formed by dissolving the chiral phosphine-amine compound and triethylamine in toluene into an ice-water bath according to a molar ratio of the chiral phosphine-amine compound to the chlorinated phosphite to the triethylamine of 1: (1-2): (3-5), heating the reaction solution to 18-25 DEG C, stirring and reacting for 10-30 hours, filtering, and carrying out column chromatography to remove the solvent, and recrystallizing to obtain the required phosphine-phosphoramidite ligand. According to the present invention, the asymmetric hydrogenation reaction of the catalyst formed by the ligand and the metal precursor on the double bonds such as C = C, C = N, C = O and the like can achieve the enantioselectivity of 99%; the catalyst is high in activity, and TON reaches up to 10000.
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Paragraph 0054-0057; 0081-0084; 0087-0088

(2021/05/22)

Mechanistically Guided One Pot Synthesis of Phosphine-Phosphite and Its Implication in Asymmetric Hydrogenation
Although hybrid bidentate ligands are known to yield highly enantioselective products in asymmetric hydrogenation (AH), synthesis of these ligands is an arduous process. Herein, a one pot, atom-economic synthesis of a hybrid phosphine-phosphite (L1) is reported. After understanding the reactivity difference between an O-nucleophile versus C-nucleophile, one pot synthesis of Senphos (L1) was achieved (72 %). When L1 was treated with [Rh], 31P NMR revealed bidentate coordination to Rh. Senphos, in the presence of rhodium, catalyzes the AH of Methyl-2-acetamido-3-phenylacrylate and discloses an unprecedented turn over frequency of 2289, along with excellent enantio-selectivity (92 %). The generality is demonstrated by hydrogenating an array of alkenes. The AH operates under mild conditions of 1–2 bar H2 pressure, at room temperature. The practical relevance of L1 is demonstrated by scaling-up the reaction to 1 g and by synthesizing DOPA, a drug widely employed for the treatment of Parkinson's disease. Computational insights indicate that the R isomer is preferred by 3.8 kcal/mol over the S isomer.
Chikkali, Samir H.,Kumar, Pawan,Kumar, Rohit,Pandey, Swechchha,Sen, Anirban,Vanka, Kumar,Vipin Raj, K.
supporting information

(2022/01/11)

PHANE-TetraPHOS, the First D2 Symmetric Chiral Tetraphosphane. Synthesis, Metal Complexation, and Application in Homogeneous Stereoselective Hydrogenation
PHANE-TetraPHOS, a new D2 symmetric tetraphosphane based on the [2.2]paracyclophane scaffold, has been synthesized and characterized. The peculiarity of this system is the presence of four homotopic diphenylphosphane groups, exchangeable through C2 symmetry operations and consequently indistinguishable. Their spatial arrangement allows the simultaneous complexation of two metal atoms. Enantiomeric purity was attained at tetra-phosphane oxide level by fractional crystallization of the diastereomeric adducts obtained from the racemate with enantiopure dibenzoyltartaric acids. Alkaline treatment of diastereomerically pure adducts followed by exhaustive P?O groups reduction with HSiCl3 gave both PHANE-TetraPHOS antipodes in an enantiopure state. They were tested as rhodium ligands in the homogeneous enantioselective hydrogenation of some benchmark unsaturated compounds. Catalytic activity and enantiodiscrimination ability were found comparable to those exhibited by the complexes of the parent bidentate ligand PHANEPHOS, but only half a mole of precious chiral ligand was employed.
Benincori, Tiziana,Cirilli, Roberto,Pierini, Marco,Rizzo, Simona,Terraneo, Giancarlo,Vaghi, Luca
p. 2367 - 2374
(2021/06/25)

A robust and stereocomplementary panel of ene-reductase variants for gram-scale asymmetric hydrogenation
We report an engineered panel of ene-reductases (ERs) from Thermus scotoductus SA-01 (TsER) that combines control over facial selectivity in the reduction of electron deficient C[dbnd]C double bonds with thermostability (up to 70 °C), organic solvent tolerance (up to 40 % v/v) and a broad substrate scope (23 compounds, three new to literature). Substrate acceptance and facial selectivity of 3-methylcyclohexenone was rationalized by crystallisation of TsER C25D/I67T and in silico docking. The TsER variant panel shows excellent enantiomeric excess (ee) and yields during bi-phasic preparative scale synthesis, with isolated yield of up to 93 % for 2R,5S-dihydrocarvone (3.6 g). Turnover frequencies (TOF) of approximately 40 000 h?1 were achieved, which are comparable to rates in hetero- and homogeneous metal catalysed hydrogenations. Preliminary batch reactions also demonstrated the reusability of the reaction system by consecutively removing the organic phase (n-pentane) for product removal and replacing with fresh substrate. Four consecutive batches yielded ca. 27 g L?1 R-levodione from a 45 mL aqueous reaction, containing less than 17 mg (10 μM) enzyme and the reaction only stopping because of acidification. The TsER variant panel provides a robust, highly active and stereocomplementary base for further exploitation as a tool in preparative organic synthesis.
Nett, Nathalie,Duewel, Sabine,Schmermund, Luca,Benary, Gerrit E.,Ranaghan, Kara,Mulholland, Adrian,Opperman, Diederik J.,Hoebenreich, Sabrina
(2021/01/25)

Generation of Functionalized Alkyl Radicals via the Direct Photoexcitation of 2,2′-(Pyridine-2,6-diyl)diphenol-Based Borates
A new type of alkylborate was developed for the purpose of generating radicals via direct photoexcitation. These borates were prepared using 2,2′-(pyridine-2,6-diyl)diphenol as a tridentate ligand together with organoboronic acids or potassium trifluoroborates. The ready availability of organoboron compounds is a significant advantage of this direct photoexcitation protocol. The excited states of these borates can also serve as strong reductants, enabling various transformations.
Miyamoto, Yusuke,Sumida, Yuto,Ohmiya, Hirohisa
supporting information
p. 5865 - 5870
(2021/07/31)

P-chirogenic diphosphazanes with axially chiral substituents and their use in rh-catalyzed asymmetric hydrogenation
A convenient synthesis of enantiopure P-chirogenic diphosphazanes incorporating bulky bisphenol and 1,1′-bi-2-naphtholderived substituents via the functionalization of a readily accessible enantiopure lithium phosphinoamide with chlorophosphoridites was developed. Since the product requires no subsequent deprotection, the protocol provides an easy, convenient synthesis of P-chirogenic ligands on the gram scale. The ligands were applied in the Rh-catalyzed asymmetric hydrogenation of benchmark substrates furnishing enantiomeric excess values up to 96%.
Moritz, Jan-Ole,Chakrabortty, Soumyadeep,Bernd H. Mu.ller,Spannenberg, Anke,Kamer, Paul C. J.
p. 14537 - 14544
(2020/12/29)

Photocatalytic Hydromethylation and Hydroalkylation of Olefins Enabled by Titanium Dioxide Mediated Decarboxylation
A versatile method for the hydromethylation and hydroalkylation of alkenes at room temperature is achieved by using the photooxidative redox capacity of the valence band of anatase titanium dioxide (TiO2). Mechanistic studies support a radical-based mechanism involving the photoexcitation of TiO2 with 390 nm light in the presence of acetic acid and other carboxylic acids to generate methyl and alkyl radicals, respectively, without the need for stoichiometric base. This protocol is accepting of a broad scope of alkene and carboxylic acids, including challenging ones that produce highly reactive primary alkyl radicals and those containing functional groups that are susceptible to nucleophilic substitution such as alkyl halides. This methodology highlights the utility of using heterogeneous semiconductor photocatalysts such as TiO2 for promoting challenging organic syntheses that rely on highly reactive intermediates.
Zhu, Qilei,Nocera, Daniel G.
supporting information
p. 17913 - 17918
(2020/12/04)

Inexpensive and rapid hydrogenation catalyst from CuSO4/CoCl2 — Chemoselective reduction of alkenes and alkynes in the presence of benzyl protecting groups
The simple reduction of a number of alkenes and alkynes was performed with a typical reaction time of 20 min using a copper-cobalt catalytic system. The reduction did not cleave benzyl protecting groups which are usually vulnerable to catalytic hydrogenation reactions. The catalyst can be prepared in situ by reduction of the inexpensive precursor salts CuSO4 and CoCl2 with NaBH4. Sodium borohydride was also used as an easily handled hydrogen source for the catalytic reductions. No pressure, heating or inert atmosphere is required and purification/catalyst removal is achieved using extraction procedures, making this approach simple and efficient.
Ficker, Mario,Svenningsen, S?ren W.,Larribeau, Thomas,Christensen, J?rn B.
supporting information
p. 1125 - 1129
(2018/02/21)

Modular 1,1′-Ferrocenediyl-cored P-Stereogenic Diphosphines: ′′JDayPhos′′ Series and its Use in Rhodium(I)-Catalyzed Hydrogenation
A novel ferrocene-based P-stereogenic diphospine ligand series dubbed JDayPhos was developed, which rhodium(I) complexes of some of its members exhibited excellent enantioselectivity (up to >99% ee) and high activity in asymmetric hydrogenation of β-unsubstituted or -substituted itaconates and α-methylene-γ-oxo-carboxylates. (Figure presented.).
Poklukar, Ga?per,Stephan, Michel,Mohar, Barbara
supporting information
p. 2566 - 2570
(2018/05/16)

STABILIZATION OF ACTIVE METAL CATALYSTS AT METAL-ORGANIC FRAMEWORK NODES FOR HIGHLY EFFICIENT ORGANIC TRANSFORMATIONS
Metal-organic framework (MOFs) compositions based on post?synthetic metalation of secondary building unit (SBU) terminal or bridging OH or OH2 groups with metal precursors or other post-synthetic manipulations are described. The MOFs provide a versatile family of recyclable and reusable single-site solid catalysts for catalyzing a variety of asymmetric organic transformations, including the regioselective boryiation and siiylation of benzyiic C—H bonds, the hydrogenation of aikenes, imines, carbonyls, nitroarenes, and heterocycles, hydroboration, hydrophosphination, and cyclization reactions. The solid catalysts can also be integrated into a flow reactor or a supercritical fluid reactor.
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Paragraph 0247; 0257; 0338

(2019/01/07)

Palladium-catalyzed selective generation of CO from formic acid for carbonylation of alkenes
A general and selective palladium-catalyzed alkoxycarbonylation of all kinds of alkenes with formic acid (HCOOH, FA) is described. Terminal, di-, tri-, and tetra-substituted including functionalized olefins are converted into linear esters with high yields and regioselectivity. Key-to-success is the use of specific palladium catalysts containing ligands with built-in base, e.g., L5. Comparison experiments demonstrate that the active catalyst system not only facilitates isomerization and carbonylation of alkenes but also promotes the selective decomposition of HCOOH to CO under mild conditions.
Sang, Rui,Kucmierczyk, Peter,Dong, Kaiwu,Franke, Robert,Neumann, Helfried,Jackstell, Ralf,Beller, Matthias
supporting information
p. 5217 - 5223
(2018/04/24)

METHOD FOR THE PRODUCTION OF METHYLSUCCINIC ACID AND THE ANHYDRIDE THEREOF FROM CITRIC ACID
A process for the preparation of methylsuccinic acid in any form, including its salts, its mono- and diester derivatives and the anhydride thereof, which comprises reacting citric acid or a derivative thereof in decarboxylation conditions, said process comprising (i) reacting citric acid or mono- and diester derivatives thereof in a non- aqueous solvent, specifically excluding alcohols, on a metallic catalyst at a temperature between 50 to 400°C and under a partial hydrogen pressure from 0.1 to 50 bar or (ii) reacting citric acid or any salt thereof or mono-, di- and triester derivatives thereof on a metallic catalyst in solvents comprising at least 5% water, at a temperature of from 50 to 400°C under a hydrogen partial pressure from 0.1 to 400 bar
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Page/Page column 16

(2018/04/21)

METHOD FOR REDUCTION OF ORGANIC MOLECULES
A method for the reduction organic molecules comprising a Ruthenium-Triphosphine complex with aromatic ligands at the phosphors which are ortho or meta substituted.
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Paragraph 0050; 0052; 0053; 0054; 0055

(2018/02/06)

Development of efficient palladium catalysts for alkoxycarbonylation of alkenes
Herein, we report a general and efficient Pd-catalysed alkoxycarbonylation of sterically hindered and demanding olefins including a variety of tri-, tetra-substituted and 1,1-disubstituted alkenes. In the presence of 1,3-bis(tert-butyl(pyridin-2-yl)phosphanyl)propane L3 or 1,4-bis(tert-butyl(pyridin-2-yl)phosphanyl)butane L4 the desired esters are obtained in good yields and selectivities. Similar transformation is obtained using tertiary ether as showcased in the carbonylation of MTBE to the corresponding linear ester in high yield and selectivity.
Liu, Jiawang,Dong, Kaiwu,Franke, Robert,Neumann, Helfried,Jackstell, Ralf,Beller, Matthias
supporting information
p. 12238 - 12241
(2018/11/21)

PROCESS FOR DOUBLE CARBONYLATION OF ALLYL ALCOHOLS TO CORRESPONDING DIESTERS
The invention relates to a process for doubly carbonylating allyl alcohols to the corresponding diesters, wherein a linear or branched allyl alcohol is reacted with a linear or branched alkanol (alcohol) with supply of CO and in the presence of a catalytic system composed of a palladium complex and at least one organic phosphorus ligand and in the presence of a hydrogen halide selected from HCl, HBr and HI.
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Paragraph 0064; 0065; 0066

(2017/07/14)

PROCESS FOR DOUBLE CARBONYLATION OF ALLYL ETHERS TO CORRESPONDING DIESTERS
The invention relates to a process for doubly carbonylating allyl ethers to the corresponding diesters, wherein a linear or branched allyl ether is reacted with a linear or branched alkanol (alcohol) with supply of CO and in the presence of a catalytic system composed of a palladium complex and at least one organic phosphorus ligand and in the presence of a hydrogen halide selected from HCl, HBr and HI.
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Paragraph 0095; 0096

(2017/07/14)

Rhodium-catalyzed hydroformylation in γ-valerolactone as a biomass-derived solvent
Rhodium-catalyzed hydroformylation of styrene, α-methylstyrene, dimethyl itaconate, and (R)-limonene was performed in gamma-valerolactone (GVL) as a proposed biomass-based environmentally benign solvent for hydroformylation referring to toluene as a generally used conventional solvent. Both achiral (triphenylphosphine, 1,3-bis(diphenylphoshino)propane) and enantiopure bidentate phosphine ligands ((S,S)-BDPP, (R)-BINAP, (R)-QUINAP, (R,R)-DIOP, (Rc),(Sp)-JOSIPHOS, (S)-SEGPHOS, (S)-(DM)-SEGPHOS) were investigated in in situ generated Rh-diphosphine catalyst systems. In general, the catalysts' activity in GVL was lower than in toluene; however, remarkable chemo- (>99%) and regioselectivities (>95%) were achieved in GVL under identical conditions. The BDPP-modified Rh-catalyst was recycled for three consecutive cycles; however a decrease in its activity was detected.
Pongrácz, Péter,Bartal, Brigitta,Kollár, László,Mika, László T.
p. 140 - 145
(2017/09/12)

α-Phosphanyl amino acids: Diphenylphosphanyl glycines with a chiral N-substituent
The first α-phosphanyl amino acetic acids (phosphanyl glycines) with a chiral N-substituent 1a–g have been synthesized by one-pot three-component condensation of diphenylphosphane and enantiomerically pure primary amines of the type (L)- or (R)-R1R2CHNH2with glyoxylic acid monohydrate in diethyl ether at room temperature. Crystals of the N-(1S)-phenylethyl derivative 1d·MeOH, grown from methanol, contained only the (1S,αS)-diastereoisomer. In [d8]THF or CD3OD solution, however, two diastereoisomers were always observed for 1a–g, usually in a diastereoisomeric ratio in the range 67:33% to 80:20%. This, together with the general sensitivity of the phosphanylglycines to hydrolysis, H-D exchange at the acidic α-CH and facile air oxidation in CD3OD solution and decarboxylation on heating in aprotic solvents are serious shortcomings and militate against the use as ligands, e.g. in Rh- or Ir-catalyzed asymmetric hydrogenations. Nickel catalysts, generated in situ with Ni(COD)2in THF and/or 1-hexene, proved however more stable and allowed selective oligomerization of ethylene at 100?°C, probably by formation of a stabilizing [Formula presented])O?hybrid ligand in the catalyst backbone. Complexes and catalysts of this type might thus offer chances for use of this facile available asymmetric ligands.
Lach, Joanna,Peulecke, Normen,Jones, Peter G.,Dix, Ina,Heinicke, Joachim W.
supporting information
p. 795 - 802
(2016/08/17)

Enantioselective hydrogenation of olefins enhanced by metal-organic framework additives
The use of nonprotic solvents (e.g., dichloromethane, toluene) increases the enantioselectivity of the asymmetric hydrogenation of olefins with chiral [Rh(Me-BPE)(cod)]OTf [Me-BPE=1,2-bis(2,5-dimethylphospholano)ethane; cod=1,5-cyclooctadiene; OTf=triflate]. Readily available achiral metal-organic frameworks (MOFs) as additives yielded substantially enhanced reactivity. In toluene (but not dichloromethane), the MOFs adsorbed the homogeneous catalyst, which directly reduced rhodium contamination in the products of the reaction. The in situ formed heterogeneous catalyst was reused without loss in selectivity. Cat in a cage: The enantioselectivity of the asymmetric hydrogenation of olefins with a RhI catalyst is increased by using nonprotic solvents. The reactivity is enhanced by readily available achiral metal-organic frameworks (MOFs) as additives. MOFs adsorb the catalyst in toluene, which reduces metal contamination of the hydrogenation products. The in situ formed heterogeneous catalyst can be reused. Me-BPE=1,2-bis(2,5-dimethylphospholano)ethane; cod=1,5-cyclooctadiene; OTf=triflate.
Vilhanov, Beta,Ranocchiari, Marco,Van Bokhoven, Jeroen A.
p. 308 - 312
(2016/02/05)

Correlation between the Selectivity and the Structure of an Asymmetric Catalyst Built on a Chirally Amplified Supramolecular Helical Scaffold
For the first time, supramolecular helical rods composed of an achiral metal complex and a complementary enantiopure monomer provided a good level of enantioinduction in asymmetric catalysis. Mixtures containing an achiral ligand monomer (BTAPPh2, 2 mol %) and an enantiopure ligand-free comonomer (ester BTA, 2.5 mol %), both possessing a complementary benzene-1,3,5-tricarboxamide (BTA) central unit, were investigated in combination with [Rh(cod)2]BArF (1 mol %) in the asymmetric hydrogenation of dimethyl itaconate. Notably, efficient chirality transfer occurs within the hydrogen-bonded coassemblies formed by BTA Ile and the intrinsically achiral catalytic rhodium catalyst, providing the hydrogenation product with up to 85% ee. The effect of the relative content of BTA Ile as compared to the ligand was investigated. The amount of chiral comonomer can be decreased down to one-fourth of that of the ligand without deteriorating the enantioselectivity of the reaction, while the enantioselectivity decreases for mixtures containing high amounts of BTA Ile. The nonlinear relationship between the amount of chiral comonomer and the enantioselectivity indicates that chirality amplification effects are at work in this catalytic system. Also, right-handed helical rods are formed upon co-assembly of the achiral rhodium complex of BTAPPh2 and the enantiopure comonomer BTA Ile as confirmed by various spectroscopic and scattering techniques. Remarkably, the major enantiomer and the selectivity of the catalytic reaction are related to the handedness and the net helicity of the coassemblies, respectively. Further development of this class of catalysts built on chirally amplified helical scaffolds should contribute to the design of asymmetric catalysts operating with low amounts of chiral entities.
Desmarchelier, Alaric,Caumes, Xavier,Raynal, Matthieu,Vidal-Ferran, Anton,Van Leeuwen, Piet W. N. M.,Bouteiller, Laurent
supporting information
p. 4908 - 4916
(2016/05/10)

Single-Site Cobalt Catalysts at New Zr8(μ2-O)8(μ2-OH)4 Metal-Organic Framework Nodes for Highly Active Hydrogenation of Alkenes, Imines, Carbonyls, and Heterocycles
We report here the synthesis of robust and porous metal-organic frameworks (MOFs), M-MTBC (M = Zr or Hf), constructed from the tetrahedral linker methane-tetrakis(p-biphenylcarboxylate) (MTBC) and two types of secondary building units (SBUs): cubic M8(μ2-O)8(μ2-OH)4 and octahedral M6(μ3-O)4(μ3-OH)4. While the M6-SBU is isostructural with the 12-connected octahedral SBUs of UiO-type MOFs, the M8-SBU is composed of eight MIV ions in a cubic fashion linked by eight μ2-oxo and four μ2-OH groups. The metalation of Zr-MTBC SBUs with CoCl2, followed by treatment with NaBEt3H, afforded highly active and reusable solid Zr-MTBC-CoH catalysts for the hydrogenation of alkenes, imines, carbonyls, and heterocycles. Zr-MTBC-CoH was impressively tolerant of a range of functional groups and displayed high activity in the hydrogenation of tri- and tetra-substituted alkenes with TON > 8000 for the hydrogenation of 2,3-dimethyl-2-butene. Our structural and spectroscopic studies show that site isolation of and open environments around the cobalt-hydride catalytic species at Zr8-SBUs are responsible for high catalytic activity in the hydrogenation of a wide range of challenging substrates. MOFs thus provide a novel platform for discovering and studying new single-site base-metal solid catalysts with enormous potential for sustainable chemical synthesis.
Ji, Pengfei,Manna, Kuntal,Lin, Zekai,Urban, Ania,Greene, Francis X.,Lan, Guangxu,Lin, Wenbin
supporting information
p. 12234 - 12242
(2016/09/28)

A comparison of MOP-phosphonite ligands and their applications in Rh(i)- and Pd(II)-catalysed asymmetric transformations
Six chiral MOP-phosphonites have been synthesised and compared via experimental and computational methods in an effort to quantify their differing structural and electronic profiles. They were found to be electron-poor ligands in comparison to their arylphosphine analogues and have a larger trans influence in square planar Pt(ii) complexes. Four [Rh(LP)(η2:η2-cod)Cl] complexes were synthesised and characterised by NMR, HRMS and X-ray crystallography. Two [Rh(LP)2]BF4 complexes were prepared where one ligand acts as a chelating P,C-π-donor; detailed NMR studies demonstrated a hemilabile η6-coordination mode, which in one case was confirmed by X-ray crystallography. Rh(i) complexes were used as catalysts in asymmetric hydrogenation and hydroformylation reactions and in the addition of phenyl boronic acid to an isatin. Pd(ii) complexes were successfully employed in asymmetric Suzuki-Miyaura cross-coupling reactions yielding binaphthyl products. Two [Pd(LP)2Cl2] complexes were synthesised and characterised by X-ray crystallography, both adopting cis orientations, with one of the complexes crystallising as two pseudo-polymorphs.
Fleming, James T.,Wills, Corinne,Waddell, Paul G.,Harrington, Ross W.,Higham, Lee J.
supporting information
p. 15660 - 15670
(2016/10/13)

Bis-N-heterocyclic Carbene Aminopincer Ligands Enable High Activity in Ru-Catalyzed Ester Hydrogenation
Bis-N-heterocyclic carbene (NHC) aminopincer ligands were successfully applied for the first time in the catalytic hydrogenation of esters. We have isolated and characterized a well-defined catalyst precursor as a dimeric [Ru2(L)2Cl3]PF6 complex and studied its reactivity and catalytic performance. Remarkable initial activities up to 283 000 h-1 were achieved in the hydrogenation of ethyl hexanoate at only 12.5 ppm Ru loading. A wide range of aliphatic and aromatic esters can be converted with this catalyst to corresponding alcohols in near quantitative yields. The described synthetic protocol makes use of air-stable reagents available in multigram quantities, rendering the bis-NHC ligands an attractive alternative to the conventional phosphine-based systems.
Filonenko, Georgy A.,Aguila, Mae Joanne B.,Schulpen, Erik N.,Van Putten, Robbert,Wiecko, Jelena,Müller, Christian,Lefort, Laurent,Hensen, Emiel J. M.,Pidko, Evgeny A.
supporting information
p. 7620 - 7623
(2015/07/02)

Assisted Tandem Catalysis: Metathesis Followed by Asymmetric Hydrogenation from a Single Ruthenium Source
Here we report the first example of a tandem metathesis-asymmetric hydrogenation protocol where the prochiral olefin generated by metathesis is hydrogenated with high enantioselectivity by an in situ formed chiral ruthenium catalyst. We show that either the ruthenium metathesis catalysts or the ruthenium species formed during the metathesis reaction can be converted into an efficient asymmetric hydrogenation catalyst upon addition of a chiral ligand and an alcohol. The performance in asymmetric hydrogenation appears to be very dependent on the solvent, the chiral ligand, and the prochiral substrate.
Renom-Carrasco, Marc,Gajewski, Piotr,Pignataro, Luca,Devries, Johannes G.,Piarulli, Umberto,Gennari, Cesare,Lefort, Laurent
p. 2223 - 2228
(2015/07/27)

New Route to Stabilize Ruthenium Nanoparticles with Non-Isolable Chiral N-Heterocyclic Carbenes
Ru nanoparticles (RuNPs) stabilized by non-isolable chiral N-heterocyclic carbenes (NHCs), namely SIDPhNp ((4S,5S)-1,3-di(naphthalen-1-yl)-4,5-diphenylimidazolidine) and SIPhOH ((S)-3-((1S,2R)-2-hydroxy-1,2-diphenylethyl)-1-((R)-2-hydroxy-1,2-diphenylethyl)-4,5-dihydro-3H-imidazoline), have been synthesized through a new procedure that does not require isolation of the free carbenes. The obtained RuNPs have been characterized by state-of-the-art techniques and their surface chemistry has been investigated by FTIR and solid-state MAS NMR upon the coordination of CO, which indicated the presence of free and reactive Ru sites. Their catalytic activity has been tested in various hydrogenation reactions involving competition between different sites, whereby interesting differences in selectivity were observed, but no enantioselectivity.
Martnez-Prieto, Luis Miguel,Ferry, Anglique,Lara, Patricia,Richter, Christian,Philippot, Karine,Glorius, Frank,Chaudret, Bruno
p. 17495 - 17502
(2016/01/25)

A recyclable CO surrogate in regioselective alkoxycarbonylation of alkenes: Indirect use of carbon dioxide
Herein, we report a Pd-catalysed alkoxycarbonylation of alkenes based on the use of a recyclable CO2 reduction product, the crystalline and air-stable N-formylsaccharin, as a CO surrogate. The carbonylation proceeds under ambient conditions in an exceptionally complementary regioselective fashion yielding the desired branched products from styrene derivatives and valuable linear esters from alkyl-substituted alkenes.
Gehrtz,Hirschbeck,Fleischer
supporting information
p. 12574 - 12577
(2015/08/06)

Regioselective Pd-Catalyzed Methoxycarbonylation of Alkenes Using both Paraformaldehyde and Methanol as CO Surrogates
In recent years, considerable effort has focused on the development of novel carbonylative transformations using CO surrogates. Consequently, toxic CO gas can be replaced by more convenient inorganic or organic carbonyl compounds. Herein, the first regioselective methoxycarbonylation of alkenes with paraformaldehyde and methanol as CO substitutes is reported. This new procedure is applicable to a series of alkenes in the presence of a palladium catalyst under relatively mild conditions and is highly atom efficient.
Liu, Qiang,Yuan, Kedong,Arockiam, Percia-Beatrice,Franke, Robert,Doucet, Henri,Jackstell, Ralf,Beller, Matthias
supporting information
p. 4493 - 4497
(2015/04/14)

Salicylaldimine-based metal - Organic framework enabling highly active olefin hydrogenation with iron and cobalt catalysts
A robust and porous Zr metal - organic framework, sal-MOF, of UiO topology was synthesized using a salicylaldimine (sal)-derived dicarboxylate bridging ligand. Postsynthetic metalation of sal-MOF with iron(II) or cobalt(II) chloride followed by treatment with NaBEt3H in THF resulted in Fe- and Co-functionalized MOFs (sal-M-MOF, M = Fe, Co) which are highly active solid catalysts for alkene hydrogenation. Impressively, sal-Fe-MOF displayed very high turnover numbers of up to 145000 and was recycled and reused more than 15 times. This work highlights the unique opportunity of developing MOF-based earth-abundant catalysts for sustainable chemical synthesis.
Manna, Kuntal,Zhang, Teng,Carboni, Micha?l,Abney, Carter W.,Lin, Wenbin
supporting information
p. 13182 - 13185
(2015/03/30)

Enzymatic hydrogenation of diverse activated alkenes. Identification of two Bacillus old yellow enzymes with broad substrate profiles
By whole cell transformation, 32 out of 71 strains showed OYEs activity toward maleimide in the first round screening. Among them, a Bacillus strain was identified to be active toward a selection of substrates with different electron-withdrawing groups. Two OYE homologous genes, bac-oye1 and bac-oye2 were cloned from this strain and overexpressed in Escherichia coli BL21(DE3). The recombinant enzyme Bac-OYE2 showed a broader pH range (6.0-10.5), while Bac-OYE1 was so sensitive to pH that it lost most of the enzyme activity below pH 6.0 or above pH 9.0. The reaction temperature exerted similar effects on the activities of both enzymes, but the stability of Bac-OYE2 was more sensitive to the temperature than Bac-OYE1. In addition to α,β-unsaturated aldehydes, ketones, nitroalkenes, and the double activated carboxylic acids, esters, nitriles and cyclic imides, Bac-OYE1 and Bac-OYE2 also exhibited activities toward the "borderline" substrates such as unsaturated lactones, mono carboxylic esters, showing their broader substrate scopes. These enzymes also had excellent enantioselectivity as evidenced by the reductions of several α,β-unsaturated cyclic ketones, α-substituted α,β-unsaturated carboxylic esters and 2-methyl maleimide. For example, methyl 2-acetamidoacrylate was reduced by Bac-OYE1 with >99% conversion and >99% ee.
Zhang, Hailing,Gao, Xiuzhen,Ren, Jie,Feng, Jinhui,Zhang, Tongcun,Wu, Qiaqing,Zhu, Dunming
p. 118 - 125
(2014/05/20)

New chiral diphosphoramidite rhodium(I) complexes for asymmetric hydrogenation
Chiral 1,5-cyclooctadiene rhodium(I) cationic complexes with C 2-symmetric chelate diphosphoramidite ligands containing (R,R)-1,2-diaminocyclohexane as the backbone and two atropoisomeric biaryl units were easily synthesized and fully characterized by multinuclear one- and two-dimensional NMR spectroscopy and elemental analysis. These complexes were used as catalysts in the asymmetric hydrogenation of dimethyl itaconate, methyl 2-acetamidoacrylate and (Z)-methyl-2-acetamido-3-phenylacrylate. The rhodium complexes derived from diphosphoramidite ligands that contain two (R) or (S) BINOL (2,2-dihydroxy-1,1-binaphthyl) units proved to be efficient catalysts, giving complete conversion and very good enantioselectivity (up to 88% ee). An uncommon positive H2 pressure effect on the enantioselectivity was observed in the hydrogenation of dimethyl itaconate catalyzed by Rh-complex with diphosphoramidite ligand that contains two (S)-binaphthol moieties. Copyright
Drommi, Dario,Micalizzi, Giuseppe,Arena, Carmela Grazia
p. 614 - 619
(2014/08/05)

PROCESS FOR PREPARING ESTERS FROM FORMATES AND OLEFINICALLY UNSATURATED COMPOUNDS
The invention provides a process for preparing esters from formates and olefinically unsaturated compounds with catalysts based on palladium compounds. In addition, the invention discloses a polyphasic reaction mixture and nonyl methyl ester mixtures prepared by the process according to the invention.
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Paragraph 0060; 0069

(2014/10/29)

RUTHENIUM-BASED COMPLEX CATALYSTS
The present invention provides novel Ruthenium-based transition metal complex catalysts comprising specific ligands, their preparation and their use in hydrogenation processes. Such complex catalysts are inexpensive, thermally robust, and olefin selective.
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Page/Page column 53; 54; 64

(2013/03/26)

Enantioselective hydrogenation of functionalized olefins catalyzed by Rh-chiral bidentatephosphite complexes
A novel catalytic system for the hydrogenation of dimethyl itaconate has been developed by using rhodium-diphosphite complexes. These chiral diphosphite ligands were derived from glucopyranoside, d-mannitol derivatives, and binaphthyl or H8-binaphthyl phosphochloridites. The ligands based on the methyl 3,6-anhydro-α-d-glucopyranoside backbone and (R)- and (S)-binaphthol and/or (R)- and (S)-2,2′-dihydroxy-5,5′,6,6′,7, 7′,8,8′-octahydro-1,1′-binaphthol gave almost complete conversion of the dimethyl itaconate and both enantiomers of dimethyl 2-methylsuccinate with excellent enantioselectivities. The stereochemically matched combination of methyl 3,6-anhydro-α-d-glucopyranoside and H 8-(S)-binaphthyl in ligand 2,4-bis{[(S)-1,1′-H 8-binaphthyl-2,2′-diyl]-phosphite} methyl 3,6-anhydro-α- d-glucopyranoside was essential to afford dimethyl 2-methylsuccinate with up to 98% ee. The sense of the enantioselectivity of products was predominantly determined by the configuration of the biaryl moieties of the ligands. An initial screening of [Rh(cod)2]BF4 with these ligands in the hydrogenation of (E)-2-(3-butoxy-4-methoxybenzylidene)-3-methylbutanoic acid was carried out. Good enantioselectivity (75% ee) and low yield for (R)-2-(3-butoxy-4-methoxybenzyl)-3-methylbutanoic acid were obtained.
Zhao, Qing-Lu,Miao, Xiao,Wang, Lai-Lai
p. 104 - 107
(2013/04/10)

Ruthenium carbene-diether ligand complexes: Catalysts for hydrogenation of Olefins
A series of carbene-diether ligands were prepared and the corresponding Ag salts used to prepare the complexes RuHCl(PPh3)2(Im(OR) 2) (Im(OR)2 = C3H2(NCH 2CH2OR)2; R = Me (4a), t-Bu (4b), tert-hexyl (4c), Ph (4d), 2,6-i-Pr2C6H3 (4e)). In an analogous fashion the species RuHCl(PPh3)2(Y 2Im(OMe)2) (Y2Im(OMe)2 = Y 2C3(NCH2CH2OMe)2; Y 2 = C6H4 (4f), Y = Cl (4g), Me (4h)) were also synthesized. Similarly RuHCl(CO)(PPh3)2(Im(OMe) 2) (5) was prepared and readily converted to RuHCl(CO)(SIMes)(Im(OMe) 2) (6) via treatment with SIMes. The reaction of 4a with SIMes afforded RuHCl(SIMes)(Im(OMe)2)(PPh3) (7), which reacts subsequently with Na[BPh4] to give [RuH(Im(OMe)2)(SIMes)] [(η6-Ph)BPh3] (8). In a series of tests, the species 4a-h, 5, 6, and 8 were shown to catalyze the hydrogenations of 1-hexene, cyclohexene, and dimethyl itaconate. From the activity of 4a-h it is clear that the capability of the carbene-ether substituents to coordinate to the metal as well as electron-donating substituents on the carbene fragment enhances catalytic activity. Other variations such as in 5, 6, and 8 resulted in terminal-olefin-selective hydrogenation catalysts, although the zwitterionic species 8 showed significantly enhanced activity.
Wang, Tongen,Pranckevicius, Conor,Lund, Clinton L.,Sgro, Michael J.,Stephan, Douglas W.
p. 2168 - 2177
(2013/05/21)

New enantiopure P,P-bidentate bis(diamidophosphite) ligands. Application in asymmetric rhodium-catalyzed hydrogenation
Two series of new enantiopure bidentate bis(diamidophosphite) ligands with diazaphospholidine and diazaphosphepine heterocyclic backbones were prepared. The ligands have a highly modular structure, which is well suited to the synthesis of a small library of compounds. Preparation was accomplished by the successive addition of enantiomerically pure substituted diamines (N,N′-dibenzylcyclohexane-1,2-diamine (1), N,N′-dimethylcyclohexane- 1,2-diamine (2), and N,N′-dimethyl-1,1′-binaphthyl-2,2′- diamine (3)) and enantiomerically pure diols (butanediol (a), cyclohexanediol (b), di-O-isopropylidenethreitol (c), and binaphthol (d)) to phosphorus trichloride. The corresponding bis(diamidophosphite) selenides were prepared, and the 1JPSe values were calculated in order to evaluate the σ-donor ability of the new ligands. The cationic Rh(I) complexes [Rh(COD)(P,P)]BF4 were synthesized with 8 of the 12 new bis(diamidophosphite) ligands. The complexes were used as catalytic precursors for the asymmetric hydrogenation of benchmark substrates, namely methyl α-acetamidoacrylate (4), methyl (Z)-α-acetamidocinnamate (5), and dimethyl itaconate (6). The influence of the nature of both the terminal and bridging fragments of the bis(diamidophosphite) ligands on the asymmetric induction is discussed. Most proved to be effective catalysts for the process, attaining total conversion and excellent enantioselectivity (>99% ee) with the complex containing the (R;Ral,Ral;R)-3c ligand in the hydrogenation of the three substrates. The best performing catalytic precursor [Rh(COD)((R;Ral,Ral;R)-3c)]BF4 was tested in the hydrogenation of selected cyclic enamides (7-9) and β-acetamidoacrylate (10).
Bravo, Maritza J.,Ceder, Rosa M.,Muller, Guillermo,Rocamora, Merce
p. 2632 - 2642
(2013/06/27)

Ligand self-sorting and nonlinear effects in dinuclear asymmetric hydrogenation: Complexity in catalysis
Self-sorting species: Nonlinear effects are observed in asymmetric hydrogenation reactions if self-sorted dinuclear complexes are generated. The nature of the substrate also influences this effect, because it affects the solubility of racemic self-sorted homochiral dinuclear complexes (see scheme). Copyright
Terrade, Frederic G.,Lutz, Martin,Reek, Joost N. H.
supporting information
p. 10458 - 10462
(2013/08/23)

A fully integrated continuous-flow system for asymmetric catalysis: Enantioselective hydrogenation with supported ionic liquid phase catalysts using supercritical CO2 as the mobile phase
A continuous-flow process based on a chiral transition-metal complex in a supported ionic liquid phase (SILP) with supercritical carbon dioxide (scCO 2) as the mobile phase is presented for asymmetric catalytic transformations of low-volatility organic substrates at mild reaction temperatures. Enantioselectivity of >99 % ee and quantitative conversion were achieved in the hydrogenation of dimethylitaconate for up to 30 h, reaching turnover numbers beyond 100 000 for the chiral QUINAPHOS-rhodium complex. By using an automated high-pressure continuous-flow setup, the product was isolated in analytically pure form without the use of any organic co-solvent and with no detectable catalyst leaching. Phase-behaviour studies and high-pressure NMR spectroscopy assisted the localisation of optimum process parameters by quantification of substrate partitioning between the IL and scCO2. Fundamental insight into the molecular interactions of the metal complex, ionic liquid and the surface of the support in working SILP catalyst materials was gained by means of systematic variations, spectroscopic studies and labelling experiments. In concert, the obtained results provided a rationale for avoiding progressive long-term deactivation. The optimised system reached stable selectivities and productivities that correspond to 0.7 kg L-1 h -1 space-time yield and at least 100 kg product per gram of rhodium, thus making such processes attractive for larger-scale application. Copyright
Hintermair, Ulrich,Francio, Giancarlo,Leitner, Walter
p. 4538 - 4547
(2013/05/08)

Carbanion-accelerated claisen rearrangements: Asymmetric induction with chiral phosphorus-stabilized anions
The carbanion-accelerated Claisen rearrangement has been extended to include phosphorus carbanion-stabilizing groups. The appropriately substituted allyl vinyl ethers are synthesized by the nucleophilic addition of allyl oxides to phosphorus-substituted allenes, which are obtained in one step from simple starting materials. The phosphorus-stabilized, carbanion-accelerated Claisen rearrangements proceed rapidly at room temperature in high yield, and the rearrangements are highly site- and stereoselective. The first examples of asymmetric induction in the Claisen rearrangement with chiral, phosphorus, anion-stabilizing groups are described. The observed asymmetric induction is highly dependent on the structure of the auxiliary and the metal counterion involved. Both internal and relative diastereoselectivity are high. A model for the observed sense of internal diastereoselectivity is proposed that is founded in the current understanding of the structure of phosphorus-stabilized anions.
Denmark, Scott E.,Marlin, John E.,Rajendra
p. 66 - 82
(2013/04/23)

A single enantiomer (99 %) directly from continuous-flow asymmetric hydrogenation
Chemistry in a shower: Dibutyl itaconate is hydrogenated in a solventless reaction to dibutyl (S)-(-)-methylsuccinate at ambient temperature and 5 bar. The product is recovered directly from a flow system. Copyright
Duque, Ruben,Pogorzelec, Peter J.,Cole-Hamilton, David J.
supporting information
p. 9805 - 9807
(2013/09/23)

Asymmetric hydrogenation using rhodium complexes generated from mixtures of monodentate neutral and anionic phosphorus ligands
A series of monodentate neutral and anionic phosphorus ligands was synthesized and evaluated in the asymmetric rhodium-catalyzed hydrogenation of functionalized olefins by using either catalysts containing identical ligands or catalysts generated from mixtures of two different ligands. We expected that the combination of an anionic ligand with a neutral ligand would favor the formation of hetero over homo bis-ligand complexes due to charge repulsion. NMR spectroscopic studies confirmed that charge effects can indeed shift the equilibrium toward the hetero bis-ligand complexes. In several cases, the combination of a neutral phosphane with an anionic phosphane, one chiral and the other achiral, furnished significantly higher enantioselectivities than analogous mixtures of two neutral ligands. The best results were obtained with a mixture of an anionic phosphoramidite and a neutral phosphoric acid diester. It is supposed that in this case a hydrogen bond between the two ligands additionally stabilizes the hetero ligand combination. Charge effects and hydrogen bonding favor the formation of rhodium hetero bis-ligand complexes from mixtures of neutral and anionic monodentate phosphorus ligands. The combination of a neutral phosphoric acid diester as a hydrogen donor and an anionic phosphoramidite as a hydrogen acceptor gives very high enantioselectivities in Rh-catalyzed hydrogenation reactions, thus exceeding the ee values of the corresponding homo bis-ligand complexes (see scheme). Copyright
Frank, Dominik J.,Franzke, Axel,Pfaltz, Andreas
p. 2405 - 2415
(2013/03/28)

A unique palladium catalyst for efficient and selective alkoxycarbonylation of olefins with formates
Forget about CO! Carbonylations are among the most important homogeneously catalyzed reactions in the chemical industry, but typically require carbon monoxide. Instead, straightforward and efficient alkoxycarbonylations of olefins can proceed with alkyl formates in the presence of a specific palladium catalyst. Aromatic, terminal aliphatic, and internal olefins are carbonylated to give industrially important linear esters at low catalyst loadings. Copyright
Fleischer, Ivana,Jennerjahn, Reiko,Cozzula, Daniela,Jackstell, Ralf,Franke, Robert,Beller, Matthias
p. 417 - 420
(2013/04/24)

Magnetic nanoparticles entrapped in siliceous mesocellular foam: A new catalyst support
γ-Fe2O3 nanoparticles were formed inside the cage-like pores of mesocellular foam (MCF). These magnetic nanoparticles showed a uniform size distribution that could be easily controlled by the MCF pore size, as well as by the hydrocarbon chain length used for MCF surface modification. Throughout the entrapment process, the pore structure and surface area of the MCF remained intact. The resulting magnetic MCF facilitated the immobilization of biocatalysts, homogeneous catalysts, and nanoclusters. Moreover, the MCF allowed for facile catalyst recovery by using a simple magnet. The supported catalysts exhibited excellent catalytic efficiencies that were comparable to their homogeneous counterparts. Copyright
Lee, Su Seong,Riduan, Siti Nurhanna,Erathodiyil, Nandanan,Lim, Jaehong,Cheong, Jian Liang,Cha, Junhoe,Han, Yu,Ying, Jackie Y.
experimental part
p. 7394 - 7403
(2012/07/27)

A cis-bis-mixed-carbene ruthenium hydride complex: An olefin-selective hydrogenation catalyst
The N-heterocyclic carbene C3H2N2(CH 2CH2OMe)2 (1; IOMe) reacts with RuHCl(PPh 3)3 to give RuClH(IOMe)(PPh3)2 (2), which reacts further with SIMes to give the cis-bis-mixed-carbene complex RuClH(IOMe)(SIMes)(PPh3) (3). This species has been shown to be a highly effective hydrogenation catalyst that tolerates the presence of a wide range of functional and donor groups.
Lund, Clinton L.,Sgro, Michael J.,Cariou, Renan,Stephan, Douglas W.
scheme or table
p. 802 - 805
(2012/04/17)

ORGANOPHOSPHORUS COMPOUNDS BASED ON TETRAPHENOL (TP)-SUBSTITUTED STRUCTURES
The invention relates to the synthesis of tetraphenol-substituted structures, in particular meta-substituted xylenes. Said tetraphenol-type structures are reacted to obtain organic phosphorus compounds, in particular organophosphites. The invention further relates to the production of catalytically active compositions which contain transition metals in addition to the aforementioned organic phosphorus compounds. According to another subject matter of the invention, said catalytically active compositions are used in chemical reactions with small molecules, e.g. HCN, CO, hydrogen, and amines.
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(2012/08/08)

Nicotinamide-dependent Ene reductases as alternative biocatalysts for the reduction of activated alkenes
Four NAD(P)H-dependent non-flavin ene reductases have been investigated for their ability to reduce activated C=C bonds in an asymmetric fashion by using 20 structurally diverse substrates. In comparison with flavin-dependent Old Yellow Enzyme homologues, a higher degree of electronic activation was required, because the best activities were obtained with enals and nitroalkenes rather than enones and carboxylic esters. Although FaEO from Fragaria x ananassa (strawberry) and its homologue SlEO from Solanum lycopersicum (tomato) exhibited a narrow substrate spectrum, progesterone 5β-reductase (At5β-StR) from Arabidopsis thaliana (thale cress) and leukotriene B4 12-hydroxydehydrogenase (LTB4DH/PGR) from Rattus norvegicus (rat) appear to be promising candidates, in particular for the asymmetric bioreduction of open-chain enals, nitroalkenes and α,β-unsaturated γ-butyrolactones. Competing nitro reduction and non-enzymatic Weitz-Scheffer epoxidation were largely suppressed. Electronically activated alkenes have been stereoselectively reduced by using a single-enzyme-cofactor system employing nicotinamide-dependent non-flavin ene reductases. Copyright
Durchschein, Katharina,Wallner, Silvia,MacHeroux, Peter,Schwab, Wilfried,Winkler, Thorsten,Kreis, Wolfgang,Faber, Kurt
p. 4963 - 4968
(2013/01/14)

A three-enzyme system involving an ene-reductase for generating valuable chiral building blocks
The use of ene-reductase (ERED) enzymes for the asymmetric reduction of olefins offers a green, renewable alternative to metal-catalysed asymmetric reduction. We report herein the first example of an ERED-catalysed enantiospecific reduction carried out at large scale using a carbonyl reductase (CRED) enzyme in the cofactor recycle. This reaction has been paired with a hydrolase-mediated regioselective ester hydrolysis to generate a valuable chiral building block using a straightforward one-pot process. Copyright
Mangan, David,Miskelly, Iain,Moody, Thomas S.
p. 2185 - 2190,6
(2020/09/02)

The non-metathetic role of Grubbs' carbene complexes: From hydrogen-free reduction of α,β-unsaturated alkenes to solid-supported sequential cross-metathesis/reduction
An efficient and high-yielding "hydrogen-free" reduction of α,β-unsaturated alkenes was carried out employing Grubbs' catalyst in a non-metathetic role and Et3SiH. Conditions were optimized under microwave irradiation. Application to the solid-phase organic synthesis allows a facile construction of sp3-sp3 carbon bonds through a sequential cross metathesis/olefin reduction.
Poeylaut-Palena, Andres A.,Testero, Sebastian A.,Mata, Ernesto G.
supporting information; experimental part
p. 1565 - 1567
(2011/03/20)

Rhenium in homogeneous catalysis: [ReBrH(NO)(labile ligand)(large-bite- angle diphosphine)] complexes as highly active catalysts in olefin hydrogenations
The reaction of [ReBr2(MeCN)(NO)(P∪P)] (P∪P = 1,1′-bisdiphenylphosphinoferrocene (dppfc) (1a), 1,1′- bisdiisopropylphosphinopherrocene (diprpfc) (1b), 2,2′- bis(diphenylphosphino)diphenyl ether (dpephos) (1c), 10,11-dihydro-4,5- bis(diphenylphosphino)dibenzo[b,f]oxepine (homoxantphos) (1d) and 4,6-bis(diphenylphosphino)-10,10-dimethylphenoxasilin (Sixantphos) (1e)) led in the presence of HSiEt3 and ethylene to formation of the ethylene hydride complexes [ReBrH(η2-C2H4)(NO) (P∪P)] (3a,b,d), the MeCN ethyl complex [ReBr(Et)(MeCN)(NO)(dpephos)] (5c) and two ortho-metalated stereoisomers of [ReBr(η2-C 2H4)(NO)( η3-o-C6H 4-Sixantphos)] 8e(up) and 8e(down). The complexes 3a,b,d, and 5c and the isomers of 8e showed high catalytic activity (TOFs ranging from 22 to 4870 h-1, TONs up to 24000) in the hydrogenation of monosubstituted olefins. For 8e(down) and 8e(up) a remarkable functional group tolerance and catalyst stability were noticed. Kinetic experiments revealed kobs to be first order in c(cat) and c(H2) and zeroth order in c(olefin). Mechanistic studies and DFT calculations suggest the catalysis to proceed along an Osborn-type catalytic cycle with olefin before H2 addition. The unsaturated key intermediates [ReBrH(NO)(P∪P)] (2a-e) could be intercepted with MeCN as [ReBrH(MeCN)(NO)(P∪P)] (10a-d) complexes or isolated as dimeric μ2-(H)2 complexes [{ReBr(μ2-H)(NO) (P∪P)}2] (9b and 9e). Variation of the bidentate ligand demonstrated a crucial influence of the (large)-bite-angle on the catalytic performance and reactivity of 3a,b,d, 5c, and 8e.
Dudle, Balz,Rajesh, Kunjanpillai,Blacque, Olivier,Berke, Heinz
scheme or table
p. 8168 - 8178
(2011/07/08)

Novel α-pinene-derived mono- and bisphosphinite ligands: Synthesis and application in catalytic hydrogenation
Novel mono- and bisphosphinite (-)-pinane-based ligands have been synthesized from (-)-α-pinene. Mixed with [(COD)2Rh] +[BF4]-, these ligands displayed moderate up to high catalytic activity in hydrogenation of dimethyl itaconate with dihydrogen. It has been observed that the structure of the ligand, the reaction temperature and solvent are important to define productivity of the phosphinite-based Rh-catalysts. Bisphosphinite ligands in hydrogenation reactions suffered from an Arbuzov rearrangement, leading to fast deactivation of the hydrogenation catalyst. In contrast, monophosphinite-derived Rh-catalysts showed increased productivity as well as thermal stability. An almost quantitative conversion of dimethyl itaconate has been achieved at elevated temperatures in toluene. Alternatively, hydrogenation of dimethyl itaconate with monophosphinite ligands has been carried out in MeOH at room temperature or 40 °C and has led to a nearly quantitative conversion.
Hobu?, Dennis,Hasenj?ger, Jens,Driessen-H?lscher, Birgit,Baro, Angelika,Axenov, Kirill V.,Laschat, Sabine,Frey, Wolfgang
experimental part
p. 94 - 103
(2011/09/15)