cas 1875-88-3, 4-Chlorophenethylalcohol | Articles data

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Regiodivergent Reductive Opening of Epoxides by Catalytic Hydrogenation Promoted by a (Cyclopentadienone)iron Complex
The reductive opening of epoxides represents an attractive method for the synthesis of alcohols, but its potential application is limited by the use of stoichiometric amounts of metal hydride reducing agents (e.g., LiAlH4). For this reason, the corresponding homogeneous catalytic version with H2 is receiving increasing attention. However, investigation of this alternative has just begun, and several issues are still present, such as the use of noble metals/expensive ligands, high catalytic loading, and poor regioselectivity. Herein, we describe the use of a cheap and easy-To-handle (cyclopentadienone)iron complex (1a), previously developed by some of us, as a precatalyst for the reductive opening of epoxides with H2. While aryl epoxides smoothly reacted to afford linear alcohols, aliphatic epoxides turned out to be particularly challenging, requiring the presence of a Lewis acid cocatalyst. Remarkably, we found that it is possible to steer the regioselectivity with a careful choice of Lewis acid. A series of deuterium labeling and computational studies were run to investigate the reaction mechanism, which seems to involve more than a single pathway.
De Vries, Johannes G.,Gandini, Tommaso,Gennari, Cesare,Jiao, Haijun,Pignataro, Luca,Stadler, Bernhard M.,Tadiello, Laura,Tin, Sergey
p. 235 - 246
(2022/01/03)

Borane evolution and its application to organic synthesis using the phase-vanishing method
Although borane is a useful reagent, it is difficult to handle. In this study, borane was generated in situ from NaBH4 or nBu4NBH4 with several oxidants using a phase-vanishing (PV) method. The borane generated was directly reacted with alkenes, affording the desired alcohols in good yields after oxidation with H2O2 under basic conditions. The selective reduction of carboxylic acids with the evolved borane was examined. The organoboranes generated by the PV method successfully underwent Suzuki–Miyaura coupling. Using this PV system, reactions with borane can be carried out easily and safely in a common test tube.
Soga, Nene,Yoshiki, Tomo,Sato, Aoi,Kawamoto, Takuji,Ryu, Ilhyong,Matsubara, Hiroshi
supporting information

(2021/03/26)

Chemoselective Cleavage of Si-C(sp3) Bonds in Unactivated Tetraalkylsilanes Using Iodine Tris(trifluoroacetate)
Organosilanes are synthetically useful reagents and precursors in organic chemistry. However, the typical inertness of unactivated Si-C(sp3) bonds under conventional reaction conditions has hampered the application of simple tetraalkylsilanes in organic synthesis. Herein we report the chemoselective cleavage of Si-C(sp3) bonds of unactivated tetraalkylsilanes using iodine tris(trifluoroacetate). The reaction proceeds smoothly under mild conditions (-50 °C to room temperature) and tolerates various polar functional groups, thus enabling subsequent Tamao-Fleming oxidation to provide the corresponding alcohols. NMR experiments and density functional theory calculations on the reaction indicate that the transfer of alkyl groups from Si to the I(III) center and the formation of the Si-O bond proceed concertedly to afford an alkyl-λ3-iodane and silyl trifluoroacetate. The developed method enables the use of unactivated tetraalkylsilanes as highly stable synthetic precursors.
Matsuoka, Keitaro,Komami, Narumi,Kojima, Masahiro,Mita, Tsuyoshi,Suzuki, Kimichi,Maeda, Satoshi,Yoshino, Tatsuhiko,Matsunaga, Shigeki
supporting information
p. 103 - 108
(2021/01/13)

Erbium-Catalyzed Regioselective Isomerization-Cobalt-Catalyzed Transfer Hydrogenation Sequence for the Synthesis of Anti-Markovnikov Alcohols from Epoxides under Mild Conditions
Herein, we report an efficient isomerization-transfer hydrogenation reaction sequence based on a cobalt pincer catalyst (1 mol %), which allows the synthesis of a series of anti-Markovnikov alcohols from terminal and internal epoxides under mild reaction conditions (≤55 °C, 8 h) at low catalyst loading. The reaction proceeds by Lewis acid (3 mol % Er(OTf)3)-catalyzed epoxide isomerization and subsequent cobalt-catalyzed transfer hydrogenation using ammonia borane as the hydrogen source. The general applicability of this methodology is highlighted by the synthesis of 43 alcohols from epoxides. A variety of terminal (23 examples) and 1,2-disubstituted internal epoxides (14 examples) bearing different functional groups are converted to the desired anti-Markovnikov alcohols in excellent selectivity and yields of up to 98%. For selected examples, it is shown that the reaction can be performed on a preparative scale up to 50 mmol. Notably, the isomerization step proceeds via the most stable carbocation. Thus, the regiochemistry is controlled by stereoelectronic effects. As a result, in some cases, rearrangement of the carbon framework is observed when tri-and tetra-substituted epoxides (6 examples) are converted. A variety of functional groups are tolerated under the reaction conditions even though aldehydes and ketones are also reduced to the respective alcohols under the reaction conditions. Mechanistic studies and control experiments were used to investigate the role of the Lewis acid in the reaction. Besides acting as the catalyst for the epoxide isomerization, the Lewis acid was found to facilitate the dehydrogenation of the hydrogen donor, which enhances the rate of the transfer hydrogenation step. These experiments additionally indicate the direct transfer of hydrogen from the amine borane in the reduction step.
Liu, Xin,Longwitz, Lars,Spiegelberg, Brian,T?njes, Jan,Beweries, Torsten,Werner, Thomas
p. 13659 - 13667
(2020/11/30)

A General Method for Photocatalytic Decarboxylative Hydroxylation of Carboxylic Acids
A general and practical method for decarboxylative hydroxylation of carboxylic acids was developed through visible light-induced photocatalysis using molecular oxygen as the green oxidant. The addition of NaBH4 to in situ reduce the unstable peroxyl radical intermediate much broadened the substrate scope. Different sp3 carbon-bearing carboxylic acids were successfully employed as substrates, including phenylacetic acid-type substrates, as well as aliphatic carboxylic acids. This transformation worked smoothly on primary, secondary, and tertiary carboxylic acids.
Khan, Shah Nawaz,Zaman, Muhammad Kashif,Li, Ruining,Sun, Zhankui
p. 5019 - 5026
(2020/05/01)

Control of Homocoupling Versus Reduction in Titanium(III)-Mediated Radical Opening of Styrene Oxides
We describe the use of titanocene monochloride in the implementation of an experimental procedure that enables control of the homolytic opening of styrene oxides in a chemoselectively controlled manner. This leads either to homocoupling products or to phenethyl alcohol derivatives. The process occurs via the generation of benzyl radicals, which may undergo a) recombination or b) reduction, yielding benzyl-Ti(IV) species upon subsequent addition of H2O to the corresponding hydroxylated compounds. The main goal of this work is the study of the reactivity pattern of styrene oxides towards the formation of the mentioned products, thereby adding value to this interesting building block.
González-Delgado, José A.,Arteaga, Jesús F.
p. 7864 - 7869
(2019/12/27)

Diaminodiphosphine tetradentate ligand and ruthenium complex thereof, and preparation methods and applications of ligand and complex
The invention discloses a diaminodiphosphine tetradentate ligand and a ruthenium complex thereof, and preparation methods and applications of the ligand and the complex, and provides a ruthenium complex represented by a formula I, wherein L is a diaminodiphosphine tetradentate ligand represented by a formula II, and X and Y are respectively and independently chlorine ion, bromine ion, iodine ion,hydrogen negative ion or BH4. According to the present invention, the ruthenium complex exhibits excellent catalytic activity in the catalytic hydrogenation reactions of ester compounds, has high yield and high chemical selectivity, is compatible with conjugated and non-conjugated carbon-carbon double bond, carbon-carbon triple bond, epoxy, halogen, carbonyl and other functional groups, and hasgreat application prospects.
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Paragraph 0301-0303; 0305

(2019/11/04)

Synthetic method for 2-(4-chlorophenyl)ethanol
The invention discloses a synthetic method for 2-(4-chlorophenyl)ethanol. The method comprises the following steps: using ethyl (4-chlorophenyl)acetate as a starting material, firstly, placing the ethyl (4-chlorophenyl)acetate, isopropanol and an appropriate amount of tetrahydrofuran solvent into a reactor, performing heating under stirring, adding sodium borohydride in batches at a reflux temperature, performing a reaction for 28-30 h (or extending the reaction time at room temperature), stopping the reaction, performing cooling to room temperature, performing acidification treatment (to be about neutral), allowing the acidified material to stand for layering, retaining an organic layer, performing extraction on an aqueous layer by using ethyl acetate, merging organic layers, performing washing by using a saturated salt solution, performing rotary evaporation at 40-60 DEG C to remove a solvent, and performing filtration on a crude product by using a silica gel column to obtain the higher-purity 2-(4-chlorophenyl)ethanol.
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Paragraph 0016; 0035-0058

(2019/10/01)

Photochemical Homologation for the Preparation of Aliphatic Aldehydes in Flow
Cheap and readily available aqueous formaldehyde was used as a formylating reagent in a homologation reaction with nonstabilized diazo compounds, enabled by UV photolysis of bench-stable oxadiazolines in a flow photoreactor. Various aliphatic aldehydes were synthesized along with the corresponding derivatized alcohols and benzimidazoles. No transition-metal catalyst or additive was required to affect the reaction, which proceeded at room temperature in 80 min.
Chen, Yiding,Leonardi, Marco,Dingwall, Paul,Labes, Ricardo,Pasau, Patrick,Blakemore, David C.,Ley, Steven V.
p. 15558 - 15568
(2019/01/04)

Synthesis method of p-chlorophenethyl alcohol
The invention discloses a synthesis method of p-chlorophenethyl alcohol. The synthesis method comprises the following steps of enabling paradichlorobenzene and a magnesium chip to generate a Grignardreaction in an ether solvent to generate a Grignard reagent, then enabling the Grignard reagent to generate an addition reaction with epoxy ethane, depressurizing after the reaction is completed, recovering the ether solvent, subsequently, quenching through acid water, adding a solvent, extracting, separating liquid, water scrubbing, drying and filtering an organic phase, depressurizing, recovering an extracting solvent, finally, distilling and collecting a fraction, so that the target-product p-chlorophenethyl alcohol can be obtained. According to the synthesis method, the paradichlorobenzeneis used; chlorine atoms are 1,4-orientating groups; isomeric impurities with other substitution positions are difficultly produced; a product is easily separated and purified and the synthesis methodhas advantages that the comprehensive raw-material cost is low, the safety coefficient is high, the three wastes are easily treated, steps are a few and the yield is high, and the like.
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Paragraph 0021-0032

(2018/05/15)

Regioselective hydrosilylation of epoxides catalysed by nickel(II) hydrido complexes
Bench-stable nickel fluoride complexes bearing NNN pincer ligands have been employed as precursors for the regioselective hydrosilylation of epoxides at room temperature. A nickel hydride assisted epoxide opening is followed by the cleavage of the newly formed nickel oxygen bond by σ-bond metathesis with a silane.
Wenz, Jan,Wadepohl, Hubert,Gade, Lutz H.
p. 4308 - 4311
(2017/04/21)

Visible-Light-Mediated Anti-Markovnikov Hydration of Olefins
Considering that stoichiometric borane and oxidant are required in the classical alkene anti-Markovnikov hydration process, it remains appealing to achieve the transformation in a catalytic protocol. Herein, a visible-light-mediated anti-Markovnikov addition of water to alkenes by using an organic photoredox catalyst in conjunction with a redox-active hydrogen atom donor was developed, which avoided the need for a transition-metal catalyst, stoichiometric borane, as well as oxidant. Both terminal and internal olefins are readily accommodated in this transformation to obtain corresponding primary and secondary alcohols in good yields with single regioselectivity. This procedure can be scaled up to gram scale with a 230 turnover number based on photocatalyst.
Hu, Xia,Zhang, Guoting,Bu, Faxiang,Lei, Aiwen
p. 1432 - 1437
(2017/08/09)

Biocatalytic Formal Anti-Markovnikov Hydroamination and Hydration of Aryl Alkenes
Biocatalytic anti-Markovnikov alkene hydroamination and hydration were achieved based on two concepts involving enzyme cascades: epoxidation-isomerization-amination for hydroamination and epoxidation-isomerization-reduction for hydration. An Escherichia coli strain coexpressing styrene monooxygenase (SMO), styrene oxide isomerase (SOI), ω-transaminase (CvTA), and alanine dehydrogenase (AlaDH) catalyzed the hydroamination of 12 aryl alkenes to give the corresponding valuable terminal amines in high conversion (many ≥86%) and exclusive anti-Markovnikov selectivity (>99:1). Another E. coli strain coexpressing SMO, SOI, and phenylacetaldehyde reductase (PAR) catalyzed the hydration of 12 aryl alkenes to the corresponding useful terminal alcohols in high conversion (many ≥80%) and very high anti-Markovnikov selectivity (>99:1). Importantly, SOI was discovered for stereoselective isomerization of a chiral epoxide to a chiral aldehyde, providing some insights on enzymatic epoxide rearrangement. Harnessing this stereoselective rearrangement, highly enantioselective anti-Markovnikov hydroamination and hydration were demonstrated to convert α-methylstyrene to the corresponding (S)-amine and (S)-alcohol in 84-81% conversion with 97-92% ee, respectively. The biocatalytic anti-Markovnikov hydroamination and hydration of alkenes, utilizing cheap and nontoxic chemicals (O2, NH3, and glucose) and cells, provide an environmentally friendly, highly selective, and high-yielding synthesis of terminal amines and alcohols.
Wu, Shuke,Liu, Ji,Li, Zhi
p. 5225 - 5233
(2017/08/17)

Anti-Markovnikov alkene oxidation by metal-oxo–mediated enzyme catalysis
Catalytic anti-Markovnikov oxidation of alkene feedstocks could simplify synthetic routes to many important molecules and solve a long-standing challenge in chemistry. Here we report the engineering of a cytochrome P450 enzyme by directed evolution to catalyze metal-oxo–mediated anti-Markovnikov oxidation of styrenes with high efficiency. The enzyme uses dioxygen as the terminal oxidant and achieves selectivity for anti-Markovnikov oxidation over the kinetically favored alkene epoxidation by trapping high-energy intermediates and catalyzing an oxo transfer, including an enantioselective 1,2-hydride migration. The anti-Markovnikov oxygenase can be combined with other catalysts in synthetic metabolic pathways to access a variety of challenging anti-Markovnikov functionalization reactions.
Hammer, Stephan C.,Kubik, Grzegorz,Watkins, Ella,Huang, Shan,Minges, Hannah,Arnold, Frances H.
p. 215 - 218
(2017/10/19)

Rhenium-Loaded TiO2: A Highly Versatile and Chemoselective Catalyst for the Hydrogenation of Carboxylic Acid Derivatives and the N-Methylation of Amines Using H2 and CO2
Herein, we report a heterogeneous TiO2-supported Re catalyst (Re/TiO2) that promotes various selective hydrogenation reactions, which includes the hydrogenation of esters to alcohols, the hydrogenation of amides to amines, and the N-methylation of amines, by using H2 and CO2. Initially, Re/TiO2 was evaluated in the context of the selective hydrogenation of 3-phenylpropionic acid methyl ester to afford 3-phenylpropanol (pH2 =5 MPa, =5 MPa, T=180 °C), which revealed a superior performance over other catalysts that we tested in this study. In contrast to other typical heterogeneous catalysts, hydrogenation reactions with Re/TiO2 did not produce dearomatized byproducts. DFT studies suggested that the high selectivity for the formation of alcohols in favor of the hydrogenation of aromatic rings is ascribed to the higher affinity of Re towards the COOCH3 group than to the benzene ring. Moreover, Re/TiO2 showed a wide substrate scope for the hydrogenation reaction (19 examples). Subsequently, this Re/TiO2 catalyst was applied to the hydrogenation of amides, the N-methylation of amines, and the N-alkylation of amines with carboxylic acids or esters.
Toyao, Takashi,Siddiki,Morita, Yoshitsugu,Kamachi, Takashi,Touchy, Abeda S.,Onodera, Wataru,Kon, Kenichi,Furukawa, Shinya,Ariga, Hiroko,Asakura, Kiyotaka,Yoshizawa, Kazunari,Shimizu, Ken-Ichi
supporting information
p. 14848 - 14859
(2017/10/27)

Antiproliferative activity and SARs of caffeic acid esters with mono-substituted phenylethanols moiety
A series of CAPE derivatives with mono-substituted phenylethanols moiety were synthesized and evaluated by MTT assay on growth of 4 human cancer cell lines (Hela, DU-145, MCF-7 and ECA-109). The substituent effects on the antiproliferative activity were systematically investigated for the first time. It was found that electron-donating and hydrophobic substituents at 2′-position of phenylethanol moiety could significantly enhance CAPE's antiproliferative activity. 2′-Propoxyl derivative, as a novel caffeic acid ester, exhibited exquisite potency (IC50?=?0.4?±?0.02 & 0.6?±?0.03?μM against Hela and DU-145 respectively).
Xie, Jin,Yang, Fengzhi,Zhang, Man,Lam, Celine,Qiao, Yixue,Xiao, Jia,Zhang, Dongdong,Ge, Yuxuan,Fu, Lei,Xie, Dongsheng
p. 131 - 134
(2016/12/27)

Preparation method for hemihydrate lorcaserin hydrochloride
The invention discloses a preparation method for hemihydrate lorcaserin hydrochloride. The preparation method comprises the following steps: (1) making a compound shown as a formula III react with ammonia to obtain a compound shown as a formula II; (2) under the protection of nitrogen gas, dissolving the compound shown as the formula II in an organic solvent, adding a hydrogen chloride solution of which the solvent is the organic solvent to salify, and adding water and cyclohexane to form a hemihydrate in order to obtain the compound shown as a formula I, wherein the organic solvent is isopropanol or 1,4-dioxane. In the preparation method disclosed by the invention, ammonium hydroxide substitutes for potassium carbonate in the prior art, so that unqualified ignition residues of a finial product caused by potassium chloride generated after salt removal can be avoided; an isopropoxide hydrochloride solution substitutes for the conventional hydrogen chloride gas, so that other impurities can be prevented from being introduced in a preparation process under the improper control of dosage and rate of the gas.
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Paragraph 0122; 0123

(2017/08/28)

Hydrogenation of Esters to Alcohols Catalyzed by Defined Manganese Pincer Complexes
The first manganese-catalyzed hydrogenation of esters to alcohols has been developed. The combination of Mn(CO)5Br with [HN(CH2CH2P(Et)2)2] leads to a mixture of cationic and neutral Mn PNP pincer complexes, which enable the reduction of various ester substrates, including aromatic and aliphatic esters as well as diesters and lactones. Notably, related pincer complexes with isopropyl or cyclohexyl substituents showed very low activity.
Elangovan, Saravanakumar,Garbe, Marcel,Jiao, Haijun,Spannenberg, Anke,Junge, Kathrin,Beller, Matthias
supporting information
p. 15364 - 15368
(2016/12/03)

Chelating Bis(1,2,3-triazol-5-ylidene) Rhodium Complexes: Versatile Catalysts for Hydrosilylation Reactions
NHC-rhodium complexes (NHC=N-heterocyclic carbenes) have been widely used as efficient catalysts for hydrosilylation reactions. However, the substrates were mostly limited to reactive carbonyl compounds (aldehydes and ketones) or carbon-carbon multiple bonds. Here, we describe the application of newly-developed chelating bis(tzNHC)-rhodium complexes (tz=1,2,3-triazol-5-ylidene) for several reductive transformations. With these catalysts, the formal reductive methylation of amines using carbon dioxide, the hydrosilylation of amides and carboxylic acids, and the reductive alkylation of amines using carboxylic acids have been achieved under mild reaction conditions.
Nguyen, Thanh V. Q.,Yoo, Woo-Jin,Kobayashi, Shu
supporting information
p. 452 - 458
(2016/02/12)

Design of a novel thiophene inhibitor of 15-lipoxygenase-1 with both anti-inflammatory and neuroprotective properties
The enzyme 15-lipoxygenase-1 (15-LOX-1) plays a dual role in diseases with an inflammatory component. On one hand 15-LOX-1 plays a role in pro-inflammatory gene expression and on the other hand it has been shown to be involved in central nervous system (CNS) disorders by its ability to mediate oxidative stress and damage of mitochondrial membranes under hypoxic conditions. In order to further explore applications in the CNS, novel 15-LOX-1 inhibitors with favorable physicochemical properties need to be developed. Here, we present Substitution Oriented Screening (SOS) in combination with Multi Component Chemistry (MCR) as an effective strategy to identify a diversely substituted small heterocyclic inhibitors for 15-LOX-1, denoted ThioLox, with physicochemical properties superior to previously identified inhibitors. Ex?vivo biological evaluation in precision-cut lung slices (PCLS) showed inhibition of pro-inflammatory gene expression and in?vitro studies on neuronal HT-22?cells showed a strong protection against glutamate toxicity for this 15-LOX-1 inhibitor. This provides a novel approach to identify novel small with favorable physicochemical properties for exploring 15-LOX-1 as a drug target in inflammatory diseases and neurodegeneration.
Eleftheriadis, Nikolaos,Poelman, Hessel,Leus, Niek G.J.,Honrath, Birgit,Neochoritis, Constantinos G.,Dolga, Amalia,D?mling, Alexander,Dekker, Frank J.
p. 786 - 801
(2016/08/30)

Photocatalytic hydrogenolysis of epoxides using alcohols as reducing agents on TiO2 loaded with Pt nanoparticles
Photoexcitation (λ > 300 nm) of TiO2 loaded with Pt particles promotes selective hydrogenolysis of epoxides using alcohols as reducing agents.
Hirakawa, Hiroaki,Shiraishi, Yasuhiro,Sakamoto, Hirokatsu,Ichikawa, Satoshi,Tanaka, Shunsuke,Hirai, Takayuki
supporting information
p. 2294 - 2297
(2015/02/05)

Screening of by-products of esfenvalerate in aqueous medium using SBSE probe desorption GC-IT-MS technique
The pyrethroids, their metabolites and by-products have been recognized as toxic to environment and human health. Despite several studies about esfenvalerate toxicity and its detection in water and sediments, information about its degradation products is still scanty. In this work, esfenvalerate degradation products were obtained by chemical oxidation with hydrogen peroxide and their structure was elucidated using a procedure known as stir bar sorptive extraction (SBSE) probe desorption gas chromatography-ion trap mass spectrometry (GC-IT-MS) analysis. This procedure consists of the thermal desorption of analytes extracted from a SBSE stir bar introduced by a probe into a gas chromatograph (GC) coupled to an ion trap mass spectrometry (IT-MS) system. Based on IT-MS data, a degradation pathway of esfenvalerate is proposed with ten products of chemical oxidation of esfenvalerate that are fully identified. Among these compounds, 3-phenoxybenzoic acid and 3-phenoxybenzaldehyde were detected, reported as being environmental metabolites of some pyrethroids, with endocrine-disrupting activity.
Colombo, Renata,Ferreira, Tanare C. R.,Yariwake, Janete H.,Lanza, Marcos R. V.
p. 1831 - 1837
(2015/09/22)

Ring Expansion of Epoxides under Br?nsted Base Catalysis: Formal [3+2] Cycloaddition of β,γ-Epoxy Esters with Imines Providing 2,4,5-Trisubstituted 1,3-Oxazolidines
A novel ring-expansion reaction of epoxides under Br?nsted base catalysis was developed. The formal [3+2] cycloaddition reaction of β,γ-epoxy esters with imines proceeds in the presence of triazabicyclodecene (TBD) as a superior Br?nsted base catalyst to afford 2,4,5-trisubstituted 1,3-oxazolidines in a highly diastereoselective manner. This reaction involves the ring opening of the epoxides with the aid of the Br?nsted base catalyst to generate α,β-unsaturated esters having an alkoxide at the allylic position, which would formally serve as a synthetic equivalent of the 1,3-dipole, followed by a cycloaddition reaction with imines in a stepwise fashion. This methodology enables the facile synthesis of enantioenriched 1,3-oxazolidines from easily accessible enantioenriched epoxides.
Kondoh, Azusa,Odaira, Kenta,Terada, Masahiro
supporting information
p. 11240 - 11244
(2016/07/06)

Direct Ruthenium-Catalyzed Hydrogenation of Carboxylic Acids to Alcohols
The "green" reduction of carboxylic acids to alcohols is a challenging task in organic chemistry. Herein, we describe a general protocol for generation of alcohols by catalytic hydrogenation of carboxylic acids. Key to success is the use of a combination of Ru(acac)3, triphos and Lewis acids. The novel method showed broad substrate tolerance and a variety of aliphatic carboxylic acids including biomass-derived compounds can be smoothly reduced.
Cui, Xinjiang,Li, Yuehui,Topf, Christoph,Junge, Kathrin,Beller, Matthias
supporting information
p. 10596 - 10599
(2015/09/02)

Highly chemoselective reduction of amides (primary, secondary, tertiary) to alcohols using SmI2/amine/H2O under mild conditions
Highly chemoselective direct reduction of primary, secondary, and tertiary amides to alcohols using SmI2/amine/H2O is reported. The reaction proceeds with C-N bond cleavage in the carbinolamine intermediate, shows excellent functional group tolerance, and delivers the alcohol products in very high yields. The expected C-O cleavage products are not formed under the reaction conditions. The observed reactivity is opposite to the electrophilicity of polar carbonyl groups resulting from the nX → πC=O (X = O, N) conjugation. Mechanistic studies suggest that coordination of Sm to the carbonyl and then to Lewis basic nitrogen in the tetrahedral intermediate facilitate electron transfer and control the selectivity of the C-N/C-O cleavage. Notably, the method provides direct access to acyl-type radicals from unactivated amides under mild electron transfer conditions.
Szostak, Michal,Spain, Malcolm,Eberhart, Andrew J.,Procter, David J.
supporting information
p. 2268 - 2271
(2014/03/21)

Mechanism of SmI2/amine/H2O-promoted chemoselective reductions of carboxylic acid derivatives (esters, acids, and amides) to alcohols
Samarium(II) iodide-water-amine reagents have emerged as some of the most powerful reagents (E° = -2.8 V) for the reduction of unactivated carboxylic acid derivatives to primary alcohols under single electron transfer conditions, a transformation that had been considered to lie outside the scope of the classic SmI2 reductant for more than 30 years. In this article, we present a detailed mechanistic investigation of the reduction of unactivated esters, carboxylic acids, and amides using SmI2-water-amine reagents, in which we compare the reactivity of three functional groups. The mechanism has been studied using the following: (i) kinetic, (ii) reactivity, (iii) radical clock, and (iv) isotopic labeling experiments. The kinetic data indicate that for the three functional groups all reaction components (SmI2, amine, water) are involved in the rate equation and that the rate of electron transfer is facilitated by base assisted deprotonation of water. Notably, the mechanistic details presented herein indicate that complexation between SmI2, water, and amines can result in a new class of structurally diverse, thermodynamically powerful reductants for efficient electron transfer to a variety of carboxylic acid derivatives. These observations will have important implications for the design and optimization of new processes involving Sm(II)-reduction of ketyl radicals. (Chemical Equation Presented).
Szostak, Michal,Spain, Malcolm,Eberhart, Andrew J.,Procter, David J.
p. 11988 - 12003
(2015/01/16)

Iron-catalysed chemo-, regio-, and stereoselective hydrosilylation of alkenes and alkynes using a bench-stable iron(II) pre-catalyst
The chemo-, regio-, and stereoselective iron-catalysed hydrosilylation of alkenes and alkynes with excellent functional group tolerance is reported (34 examples, 41-96% yield). The catalyst and reagents are commercially available and easy to handle, with the active iron catalyst being generated in situ, thus providing a simple and practical methodology for iron-catalysed hydrosilylation. The silane products can be oxidised to the anti-Markovnikov product of olefin hydration, and the one-pot iron-catalysed hydrosilylation-oxidation of olefins to give silane(di)ols directly is also reported. The iron pre-catalyst was used at loadings as low as 0.07 mol%, and displayed catalyst turnover frequencies (TOF) approaching 60,000 molh-1. Initial mechanistic studies indicate an iron(I) active catalyst.
Greenhalgh, Mark D.,Frank, Dominik J.,Thomas, Stephen P.
p. 584 - 590
(2014/05/20)

Unusually Broad Substrate Profile of Self-Sufficient Cytochrome P450 Monooxygenase CYP116B4 from Labrenzia aggregata
A new member of the CYP116B subfamily - P450LaMO - was discovered in Labrenzia aggregata by genomic data mining. It was successfully overexpressed in Escherichia coli, purified, and subsequently characterized spectroscopically, and its catalytic properties were assessed. Substrate profiling of the P450LaMO revealed that it was a versatile catalyst, exhibiting hydroxylation and epoxidation activities as well as O-dealkylation and asymmetric sulfoxidation activities. Diverse compounds, including alkylbenzenes, aromatic bicyclic molecules, and terpenoids, were shown to be hydroxylated by P450LaMO. Such diverse catalytic activities are uncommon for the bacterial P450s, and the P450LaMO -mediated stereoselective hydroxylation of inactivated C - H bonds - ubiquitous and relatively unreactive in organic molecules - is particularly unusual. The self-sufficient nature of P450LaMO, coupled with its broad substrate range, highlights it as an ideal template for directed evolution towards various applications.
Yin, Yue-Cai,Yu, Hui-Lei,Luan, Zheng-Jiao,Li, Ren-Jie,Ouyang, Peng-Fei,Liu, Jing,Xu, Jian-He
p. 2443 - 2449
(2015/03/03)

Unusually Broad Substrate Profile of Self-Sufficient Cytochrome P450 Monooxygenase CYP116B4 from Labrenzia aggregata
A new member of the CYP116B subfamily - P450LaMO - was discovered in Labrenzia aggregata by genomic data mining. It was successfully overexpressed in Escherichia coli, purified, and subsequently characterized spectroscopically, and its catalytic properties were assessed. Substrate profiling of the P450LaMO revealed that it was a versatile catalyst, exhibiting hydroxylation and epoxidation activities as well as O-dealkylation and asymmetric sulfoxidation activities. Diverse compounds, including alkylbenzenes, aromatic bicyclic molecules, and terpenoids, were shown to be hydroxylated by P450LaMO. Such diverse catalytic activities are uncommon for the bacterial P450s, and the P450LaMO -mediated stereoselective hydroxylation of inactivated C-H bonds - ubiquitous and relatively unreactive in organic molecules - is particularly unusual. The self-sufficient nature of P450LaMO, coupled with its broad substrate range, highlights it as an ideal template for directed evolution towards various applications.
Yin, Yue-Cai,Yu, Hui-Lei,Luan, Zheng-Jiao,Li, Ren-Jie,Ouyang, Peng-Fei,Liu, Jing,Xu, Jian-He
p. 2443 - 2449
(2015/08/24)

On the role of pre- and post-electron-transfer steps in the SmI 2/Amine/H2O-mediated reduction of esters: New mechanistic insights and kinetic studies
The mechanism of the SmI2-mediated reduction of unactivated esters has been studied using a combination of kinetic, radical clocks and reactivity experiments. The kinetic data indicate that all reaction components (SmI2, amine, H2O) are involved in the rate equation and that electron transfer is facilitated by Bronsted base assisted deprotonation of water in the transition state. The use of validated cyclopropyl-containing radical clocks demonstrates that the reaction occurs via fast, reversible first electron transfer, and that the electron transfer from simple Sm(II) complexes to aliphatic esters is rapid. Notably, the mechanistic details presented herein indicate that complexation between SmI2, H2O and amines affords a new class of structurally diverse, thermodynamically powerful reductants for efficient electron transfer to carboxylic acid derivatives as an attractive alternative to the classical hydride-mediated reductions and as a source of acyl-radical equivalents for C-C bond forming processes. Electron donors: The mechanism of the SmI 2-mediated reduction of unactivated esters has been studied by using a combination of kinetic, radical clock, and reactivity experiments. Notably, the mechanistic details presented herein indicate that complexation between SmI2, H2O, and amines gives a new class of structurally diverse, thermodynamically powerful reductants for efficient electron transfer to carboxylic acid derivatives as an attractive alternative to the classical hydride-mediated reductions and as a source of acyl-radical equivalents for C-C bond-forming processes (see scheme).
Szostak, Michal,Spain, Malcolm,Procter, David J.
supporting information
p. 4222 - 4226
(2014/05/06)

A Phosphine-Catalyzed Novel Asymmetric [3+2] Cycloaddition of C,N-Cyclic Azomethine Imines with δ-Substituted Allenoates
Catalytic asymmetric [3+2] cycloadditions of C,N-cyclic azomethine imines with δ-substituted allenoates have been developed in the presence of (S)-Me-f-KetalPhos, affording functionalized tetrahydroquinoline frameworks in good yields with high diastereo- and good enantioselectivities under mild condition. The substrate scope has been also examined. This is the first time that δ-substituted allenoates have been applied as a δ,γ-C-C bond participated C 2 synthon in asymmetric synthesis. Another round: Catalytic asymmetric [3+2] cycloaddition of C,N-cyclic azomethine imines with δ-substituted allenoates have been developed in the presence of (S)-Me-f-KetalPhos, affording functionalized tetrahydroquinoline frameworks in good yields with high diastereo- and good enantioselectivities under mild conditions. This is the first example applying δ-substituted allenoates as C 2 synthons in asymmetric δ,γ-C-C bond formation.
Wang, De,Lei, Yu,Wei, Yin,Shi, Min
supporting information
p. 15325 - 15329
(2016/02/18)

Iron-catalyzed reduction of carboxylic esters to alcohols
A novel catalytic system formed from Fe(stearate)2/NH 2CH2CH2NH2 and polymethylhydrosiloxane was directly developed for the hydrosilylation of carboxylic acid esters to alcohols. The catalytic method exhibits broad substrate scope, including 20 aliphatic, aromatic, and heterocyclic esters. The corresponding alcohols are obtained in moderate to very good yields. The first iron-catalyzed hydrosilylation of carboxylic acid esters to alcohols is described. A catalytic system formed by Fe(stearate)2/NH 2CH2CH2NH2 and polymethylhydrosiloxane (PMHS) is used for this transformation, which has a broad substrate scope, including 20 aliphatic, aromatic, and heterocyclic esters. The corresponding alcohols are obtained in moderate to very good yields. Copyright
Junge, Kathrin,Wendt, Bianca,Zhou, Shaolin,Beller, Matthias
p. 2061 - 2065
(2013/05/09)

CATALYTIC ANTI-MARKOVNIKOV OXIDATION AND HYDRATION OF OLEFINS
The disclosure provides a dual-catalysis system for direct conversion of olefins to alcohols. The cooperative catalytic system contains one oxidizing catalyst and one transfer-hydrogenation catalyst. A wide variety of olefins, including aromatic and aliphatic olefins, can be used as the reactant. The transformation proceeds with anti-Markovnikov selectivity, and in some aspects provides primary alcohols as major products. The disclosure further provides a system for oxidation of olefins with anti-Markovnikov selectivity.
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(2012/07/14)

Enantioselective hydrosilylation of aromatic alkenes catalyzed by chiral bis(oxazolinyl)phenyl-rhodium acetate complexes
Highly efficient and enantioselective hydrosilylation of aromatic alkenes catalyzed by the chiral rhodium acetate complexes with the bis(oxazolinyl)phenyl ligands has been reported that afforded chiral silane derivatives with up to 99% ee. Georg Thieme Ve
Naito, Tatsuo,Yoneda, Takuma,Ito, Jun-Ichi,Nishiyama, Hisao
p. 2957 - 2960
(2013/02/22)

Regioselective synthesis of substituted naphthalenes and phenanthrenes by FeCl3-promoted annulation of aryl and naphthyl acetaldehydes with alkynes
The FeCl3-promoted annulation reaction of aryl acetaldehydes with alkynes has been established, which provides a new and versatile straightforward procedure for the regioselective synthesis of mono-, di-, and polysubstituted naphthalenes under mild conditions. Interestingly, the present catalytic system not only differentiates between internal and terminal alkynes but also shows unprecedented complete Me3SiOH elimination selectivity for silyl alkyne substrates. Furthermore, the synthesis of a series of substituted phenanthrenes via reactions of nathphyl acetaldehydes with internal alkynes is also achieved for the first time in good yields with excellent regioselectivity.
Bu, Xiuli,Hong, Longcheng,Liu, Ruiting,Hong, Jianquan,Zhang, Zhengxing,Zhou, Xigeng
experimental part
p. 7960 - 7965
(2012/09/21)

Primary alcohols from terminal olefins: Formal anti-Markovnikov hydration via triple relay catalysis
Alcohol synthesis is critical to the chemical and pharmaceutical industries. The addition of water across olefins to form primary alcohols (anti-Markovnikov olefin hydration) would be a broadly useful reaction but has largely proven elusive; an indirect hydroboration/oxidation sequence requiring stoichiometric borane and oxidant is currently the most practical methodology. Here, we report a more direct approach with the use of a triple relay catalysis system that couples palladium-catalyzed oxidation, acid-catalyzed hydrolysis, and ruthenium-catalyzed reduction cycles. Aryl-substituted terminal olefins are converted to primary alcohols by net reaction with water in good yield and excellent regioselectivity.
Dong, Guangbin,Teo, Peili,Wickens, Zachary K.,Grubbs, Robert H.
scheme or table
p. 1609 - 1612
(2012/02/01)

The preparation of 3-substituted-1,5-dibromo-pentanes as precursors to heteracyclohexanes
The methodology to prepare 3-substituted 1,5-dibromopentanes I and their immediate precursors, which include 3-substituted 1,5-pentanediols VII or 4-substituted tetrahydropyrans VIII, is surveyed. Such dibromides I are important intermediates in the preparation of liquid crystalline derivatives containing 6-membered heterocyclic rings. Four dibromides 1a-1d containing simple alkyl and more complex fragments at the 3-position were prepared. 3-Propyl- and 3-pentyl-pentane-1,5-diol (2a,b) were prepared starting from either glutaconate or malonate diesters, while tetrahydropyrans 3c and 3d were obtained from tetrahydro-4H-pyran-4-one. The advantages and disadvantages of each route are discussed. Dibromides 1c and 1d were used to prepare sulfonium zwitterions 11c and 11d.
Ringstrand, Bryan,Oltmanns, Martin,Batt, Jeffrey A.,Jankowiak, Aleksandra,Denicola, Richard P.,Kaszynski, Piotr
supporting information; experimental part
p. 386 - 393
(2011/06/23)

One-pot system for reduction of epoxides using NaBH4, PdCl 2 catalyst, and moist alumina
Reduction of epoxides with sodium borohydride, a catalytic amount of palladium(II) chloride, and chromatographic neutral alumina preloaded with a small amount of water (moist alumina) in hexane gave alcohols in good to excellent yields and good selectivity of the desired products under mild conditions. The reaction system was operationally simple and environmentally friendly. The alumina can be recovered simply and reused a number of times without any treatment and with good activity.
Yakabe, Shigetaka
experimental part
p. 1339 - 1344
(2010/06/21)

Rhodium-catalysed hydroboration employing new Quinazolinap ligands; An investigation into electronic effects
As part of an ongoing effort to improve the efficiency and substrate scope of our Quinazolinap ligand series in the rhodium-catalysed asymmetric hydroboration of vinyl arenes, 2-(p-trifluoromethylphenyl)-Quinazolinap and 2-(p-methoxyphenyl)-Quinazolinap have been synthesised and resolved in good yield. These, along with the previously reported 2-(2-pyridyl)-Quinazolinap and 2-(2-pyrazinyl)-Quinazolinap, form part of an electronic series of Quinazolinap ligands synthesised in order to explore electronic effects in this ligand class. The application of this series of ligands to the rhodium-catalysed asymmetric hydroboration of a range of vinylarenes is described. Good conversions and regioselectivities as well as excellent enantioselectivities up to 97% were obtained. 2-(p-Methoxyphenyl)-Quinazolinap demonstrated consistently high enantioselectivities in the hydroboration of sterically demanding vinylarenes.
Maxwell, Aoife C.,Flanagan, Susan P.,Goddard, Richard,Guiry, Patrick J.
experimental part
p. 1458 - 1473
(2010/11/03)

Rh(I)-catalyzed asymmetric hydrosilylation and hydroboration/oxidation reactions using berens ligand
The Berens ligand 2 was used in a number of Rh(I)-catalyzed asymmetric hydrosilylations of acetophenones under standard conditions, affording the corresponding 1-arylalcohols in ees up to 65%. Some novel Rh catalysts were generated in situ from the neutral precatalyst [Rh(μ-Cl)(COD)]2 and screened in the catalytic asymmetric hydroboration/oxidation of styrenes, gave enantioselectivities of up to 62%. Copyright Taylor & Francis Group, LLC.
Marques, Carolina S.,Burke, Anthony J.
experimental part
p. 4207 - 4214
(2009/04/06)

Electronically varied quinazolinaps for asymmetric catalysis
The synthesis and resolution of electronically varied axially chiral Quinazolinaps is reported. These ligands bear different aryl groups on the donor phosphorus atom and were synthesised as part of our investigations into electronic effects within this ligand class. A diastereomerically pure palladacycle of one ligand was characterised by X-ray crystallography. The application of these Quinazolinaps to the rhodium-catalysed hydroboration of vinylarenes resulted in enantioselectivities of up to 92%. Their application to the palladium-catalysed allylic alkylation of 1,3-diphenylprop-2-enyl acetate resulted in conversions of up to 99% and enantioselectivities of up to 94%. The Royal Society of Chemistry 2008.
Maxwell, Aoife C.,Franc, Celine,Pouchain, Laurent,Mueller-Bunz, Helge,Guiry, Patrick J.
supporting information; experimental part
p. 3848 - 3853
(2009/02/05)

The active role of NHC ligands in platinum-mediated tandem hydroboration-cross coupling reactions
Stable N-heterocyclic platinum-carbene complexes are the first example of platinum-mediated regioselective H-B addition to vinylarenes and alkynes, allowing consecutive cross coupling reactions with the same catalytic system. The Royal Society of Chemistry.
Lillo, Vanesa,Mata, Jose A.,Segarra, Anna M.,Peris, Eduardo,Fernandez, Elena
p. 2184 - 2186
(2008/02/08)

Structure-guided optimization of small molecules inhibiting human immunodeficiency virus 1 Tat association with the human coactivator p300/CREB binding protein-associated factor
Human immunodeficiency virus 1 (HIV-1) trans-activator Tat recruits the human transcriptional coactivator PCAF (p300/CREB binding protein-associated factor) to facilitate transcription of the integrated HIV-1 provirus. We report here structure-based lead optimization of small-molecule inhibitors that block selectively Tat and PCAF association in cells. Our lead optimization was guided by grand-canonical ensemble simulation of the receptor/lead complex that leads to definition of chemical modifications with improved lead affinity through displacing weakly bound water molecules at the ligand-receptor interface.
Pan, Chongfeng,Mezei, Mihaly,Mujtaba, Shiraz,Muller, Michaela,Zeng, Lei,Li, Jiaming,Wang, Zhiyong,Zhou, Ming-Ming
p. 2285 - 2288
(2008/02/02)

Design and synthesis of phenethyl benzo[1,4]oxazine-3-ones as potent inhibitors of PI3Kinaseγ
The Type 1 PI3Kinases comprise a family of enzymes, which primarily phosphorylate PIP2 to give the second messenger PIP3, a key player in many intracellular signaling processes [Science, 2002, 296, 1655; Trends Pharmacol. Sci. 2003, 24, 366]. Of the four type 1 PI3Ks, the γ-isoform, which is expressed almost exclusively in leukocytes [Curr. Biol., 1997, 7, R470], is of particular interest with respect to its role in inflammatory diseases such as rheumatoid arthritis (RA) and chronic obstructive pulmonary disease (COPD) [Mol. Med. Today, 2000, 6, 347]. Investigation of a series of 4,6-disubstituted-4H-benzo[1,4]oxazin-3-ones has led to the identification of single-digit nanomolar inhibitors of PI3Kγ, several of which had good cell based activity and were shown to be active in vivo in an aspectic peritonitis model of inflammatory cell migration.
Lanni Jr., Thomas B.,Greene, Keri L.,Kolz, Christine N.,Para, Kimberly S.,Visnick, Melean,Mobley, James L.,Dudley, David T.,Baginski, Theodore J.,Liimatta, Marya B.
p. 756 - 760
(2007/10/03)

TADDOL-derived phosphites and phosphoramidites for efficient rhodium-catalyzed asymmetric hydroboration
Two simple TADDOL-derived monodentate ligands, the (1R,2S)-2- phenylcyclohexanol-derived phosphite and the N,N-(phenylbenzyl)-phosphoramidite, give comparably high levels of enantioselectivity (90-96% ee) in the rhodium-catalyzed hydroborations of substituted styrenes bearing either electron-donating or electron-withdrawing substituents. Rhodium(I) chloride and tetrafluoroborate catalyst precursors give comparable results. Pinacolborane is superior to catecholborane in these reactions.
Moteki, Shin A.,Wu, Di,Chandra, Kusum L.,Sahadeva Reddy,Takacs, James M.
p. 3097 - 3100
(2007/10/03)

Synthesis, biochemical evaluation and rationalisation of the inhibitory activity of a range of 4-substituted phenyl alkyl imidazole-based inhibitors of the enzyme complex 17α-hydroxylase/17,20-lyase (P45017α)
We report the preliminary results of the synthesis, biochemical evaluation and rationalisation of the inhibitory activity of a number of phenyl alkyl imidazole-based compounds as inhibitors of the two components of 17α-hydroxylase/17,20-lyase (P45017α), that is, 17α-hydroxylase (17α-OHase) and 17,20-lyase (lyase). The results show that N-3-(4-bromophenyl) propyl imidazole (12) (IC50 = 2.95 μM against 17α-OHase and IC50 = 0.33 μM against lyase) is the most potent compound within the current study, in comparison to ketoconazole (KTZ) (IC50 = 3.76 μM against 17α-OHase and IC50 = 1.66 μM against lyase). Modelling of these compounds suggests that the length of the alkyl chain enhances the interaction between the inhibitor and the area of the active site corresponding to the C(3) area of the steroid backbone, thereby increasing potency.
Patel, Chirag H.,Dhanani, Sachin,Owen, Caroline P.,Ahmed, Sabbir
p. 4752 - 4756
(2007/10/03)

Regio- and enantiocontrol in the room-temperature hydroboration of vinyl arenes with pinacol borane
The catalyzed hydroboration of vinyl arenes was carried out using pinacol borane instead of catechol borane, as the former reagent and the product boronates are significantly easier to handle. By careful choice of catalyst, either the branched or the linear product can be obtained in greater than 96% selectivity. Interestingly, common ligands such as BINAP and Josiphos give opposite asymmetric induction with pinacol borane as compared with catechol borane, while P,N-ligands such as Quinap gave the same sense of induction. The hydroboration of 6-methoxynaphthalene proceeded with the greatest regio- (95:5) and enantioselectivity (94:6) of all vinyl arenes examined. The hydroboration product was then employed in a concise synthesis of the nonsteroidal antiinflammatory agent, Naproxen. Copyright
Crudden, Cathleen M.,Hleba, Yonek B.,Chen, Austin C.
p. 9200 - 9201
(2007/10/03)

Preparation and resolution of a modular class of axially chiral quinazoline-containing ligands and their application in asymmetric rhodium-catalyzed olefin hydroboration
The preparation and resolution of a series of axially chiral quinazoline-containing ligands is described in which the key steps are the metal-catalyzed naphthyl-phosphorus bond formation, the naphthalene-quinazoline Suzuki coupling, and the preparation of the Suzuki electrophilic components from the corresponding imidate and anthranilic acid. Diastereomeric palladacycles derived from the racemic phosphinamines and (+)-di-μ-chlorobis[(R)- dimethyl(1-(1-naphthyl)ethyl)-aminato-C2,N]dipalladium(II) were separated by fractional crystallization. The configuration of the resulting diastereomers was determined by X-ray crystallographic analysis. Displacement of the resolving agent by reaction with 1,2-bis(diphenylphosphino)ethane afforded enantiopure ligand in each case. Their rhodium complexes were prepared and applied in the enantioselective hydroboration of a range of vinylarenes. The quinazolinap catalysts were found to be extremely active, giving excellent conversions, good to complete regioselectivities, and the highest enantioselectivities obtained to date for several members of the vinylarene class, including cis-β-methylstyrene (97%), cis-stilbene (99%), and indene (99.5%).
Connolly, David J.,Lacey, Patrick M.,McCarthy, Mary,Saunders, Cormac P.,Carroll, Anne-Marie,Goddard, Richard,Guiry, Patrick J.
p. 6572 - 6589
(2007/10/03)

Asymmetric hydrosilylation of alkenes with alkoxyhydrosilanes catalyzed by chiral bis(oxazolinyl)phenyl-rhodium complex
Asymmetric addition of alkoxyhydrosilanes to styrene derivatives was examined with chiral bis(oxazolinyl)phenyl-rhodium complex to give moderate ratios (up to 77:23) of α- and β-adducts and high enantioselectivity (up to 95% for the α-adduct).
Tsuchiya, Yasunori,Uchimura, Hirofumi,Kobayashi, Kazuki,Nishiyama, Hisao
p. 2099 - 2102
(2007/10/03)

Readily available biaryl P,N ligands for asymmetric catalysis
A short and modular synthesis of novel P,N ligands (pinap; see scheme; X = O or NH) is presented. A covalently bound chiral group allows the separation of the atropisomeric diastereomers, thus avoiding resolution involving chiral Pd-amine complexes. The utility of the ligands is demonstrated for three reactions catalyzed by different transition metals; in each case products are obtained with high enantiomeric excess (up to 99% ee).
Knoepfel, Thomas F.,Aschwanden, Patrick,Ichikawa, Takashi,Watanabe, Takumi,Carreira, Erick M.
p. 5971 - 5973
(2007/10/03)