- Asymmetric Transfer Hydrogenation of Diaryl Ketones with Ethanol Catalyzed by Chiral NCP Pincer Iridium Complexes
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The use of a chiral (NCP)Ir complex as the precatalyst allowed for the discovery of asymmetric transfer hydrogenation of diaryl ketones with ethanol as the hydrogen source and solvent. This reaction was applicable to various ortho-substituted diaryl keontes, affording benzhydrols in good yields and enantioselectivities. This protocol could be carried out in a gram scale under mild reaction conditions. The utility of the catalytic system was highlighted by the synthesis of the key precursor of (S)-neobenodine.
- Huang, Zheng,Liu, Guixia,Qian, Lu,Tang, Xixia,Wang, Yulei
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- Tunable System for Electrochemical Reduction of Ketones and Phthalimides
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Herein, we report an efficient, tunable system for electrochemical reduction of ketones and phthalimides at room temperature without the need for stoichiometric external reductants. By utilizing NaN3 as the electrolyte and graphite felt as both the cathode and the anode, we were able to selectively reduce the carbonyl groups of the substrates to alcohols, pinacols, or methylene groups by judiciously choosing the solvent and an acidic additive. The reaction conditions were compatible with a diverse array of functional groups, and phthalimides could undergo one-pot reductive cyclization to afford products with indolizidine scaffolds. Mechanistic studies showed that the reactions involved electron, proton, and hydrogen atom transfers. Importantly, an N3/HN3 cycle operated as a hydrogen atom shuttle, which was critical for reduction of the carbonyl groups to methylene groups.
- Chen, Gong,Qiao, Tianjiao,Wang, Yaxin,Zhang, Jian,Zhao, Jianyou
-
supporting information
p. 3297 - 3302
(2021/10/14)
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- Visible-Light-Driven Catalytic Deracemization of Secondary Alcohols
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Deracemization of racemic chiral compounds is an attractive approach in asymmetric synthesis, but its development has been hindered by energetic and kinetic challenges. Here we describe a catalytic deracemization method for secondary benzylic alcohols which are important synthetic intermediates and end products for many industries. Driven by visible light only, this method is based on sequential photochemical dehydrogenation followed by enantioselective thermal hydrogenation. The combination of a heterogeneous dehydrogenation photocatalyst and a chiral molecular hydrogenation catalyst is essential to ensure two distinct pathways for the forward and reverse reactions. These reactions convert a large number of racemic aryl alkyl alcohols into their enantiomerically enriched forms in good yields and enantioselectivities.
- Hu, Xile,Zhang, Zhikun
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supporting information
p. 22833 - 22838
(2021/09/09)
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- Method for synthesizing chiral secondary alcohol compound
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The invention discloses a method for synthesizing a chiral secondary alcohol compound. The method comprises the following step of: reacting a ketone compound in an aprotic organic solvent at room temperature and inert gas atmosphere under the action of a chiral cobalt catalyst and an activating agent by taking a combination of bis(pinacolato)diboron and alcohol or water as a reducing agent to obtain the chiral secondary alcohol compound. According to the method disclosed by the invention, a combination of pinacol diborate and alcohol or water which are cheap, stable and easy to obtain is taken as a reducing agent, and a ketone compound is efficiently reduced to synthesize a corresponding chiral secondary alcohol compound in an aprotic organic solvent under the action of a chiral cobalt catalyst; in a chiral cobalt catalyst adopted by the method, when a chiral ligand is PAOR, an activating agent is NaBHEt3 or NaOtBu and an adopted raw material is aromatic ketone, the yield is 80% or above, and the optical purity is 90% or above; and when the adopted raw material is alkane ketone, the yield can reach 70% or above, and the optical purity can reach 80% or above.
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-
Paragraph 0038-0043; 0099-0103
(2021/05/29)
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- Highly Enantioselective Cobalt-Catalyzed Hydroboration of Diaryl Ketones
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A highly enantioselective cobalt-catalyzed hydroboration of diaryl ketones with pinacolborane was developed using chiral imidazole iminopyridine as a ligand to access chiral benzhydrols in good to excellent yields and ee. This protocol could be carried out in a gram scale under mild reaction conditions with good functional group tolerance. Chiral biologically active 3-substituted phthalide and (S)-neobenodine could be easily constructed through asymmetric hydroboration as a key step.
- Liu, Wenbo,Guo, Jun,Xing, Shipei,Lu, Zhan
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supporting information
p. 2532 - 2536
(2020/04/02)
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- Redox-driven deracemization of secondary alcohols by sequential ether/O2-mediated oxidation and Ru-catalyzed asymmetric reduction
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The deracemization of benzylic alcohols has been achieved using a redox-driven one-pot two-step process. The racemic alcohols were oxidized by bis(methoxypropyl) ether and oxygen to give the ketone intermediates, followed by an asymmetric transfer hydrogenation with a chiral ruthenium catalyst. This compatible oxidation/reduction process gave the enantiomerically enriched alcohols with up to 95% ee values.
- Yang, Bing,Cui, Peng,Chen, Yongsheng,Liu, Qixing,Zhou, Haifeng
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supporting information
(2020/10/14)
-
- Electrochemical Hydrogenation with Gaseous Ammonia
-
As a carbon-free and sustainable fuel, ammonia serves as high-energy-density hydrogen-storage material. It is important to develop new reactions able to utilize ammonia as a hydrogen source directly. Herein, we report an electrochemical hydrogenation of alkenes, alkynes, and ketones using ammonia as the hydrogen source and carbon electrodes. A variety of heterocycles and functional groups, including for example sulfide, benzyl, benzyl carbamate, and allyl carbamate were well tolerated. Fast stepwise electron transfer and proton transfer processes were proposed to account for the transformation.
- Li, Jin,He, Lingfeng,Liu, Xu,Cheng, Xu,Li, Guigen
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supporting information
p. 1759 - 1763
(2019/01/16)
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- Substituent Position-Controlled Stereoselectivity in Enzymatic Reduction of Diaryl- and Aryl(heteroaryl)methanones
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We report here the discovery of a novel ketoreductase (KRED), named KmCR2, with a broad substrate spectrum on bioreduction of sterically bulky diaryl- and aryl(heteroaryl)methanones. The position of the substituent on aromatic rings (meta versus para or ortho) was revealed to control the stereospecificity of KmCR2. The stereoselective preparation of both enantiomers of diaryl- or aryl(heteroaryl)methanols using strategically engineered substrates with a traceless directing group (bromo group) showcased the potential application of this substrate-controlled bioreduction reaction. The combined use of substrate engineering and protein engineering, was demonstrated to be a useful strategy in efficiently improving stereoselectivity or switching stereopreference of enzymatic processes. (Figure presented.).
- Li, Zhining,Wang, Zexu,Wang, Yuhan,Wu, Xiaofan,Lu, Hong,Huang, Zedu,Chen, Fener
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supporting information
p. 1859 - 1865
(2019/03/07)
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- Combined Photoredox/Enzymatic C?H Benzylic Hydroxylations
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Chemical transformations that install heteroatoms into C?H bonds are of significant interest because they streamline the construction of value-added small molecules. Direct C?H oxyfunctionalization, or the one step conversion of a C?H bond to a C?O bond, could be a highly enabling transformation due to the prevalence of the resulting enantioenriched alcohols in pharmaceuticals and natural products,. Here we report a single-flask photoredox/enzymatic process for direct C?H hydroxylation that proceeds with broad reactivity, chemoselectivity and enantioselectivity. This unified strategy advances general photoredox and enzymatic catalysis synergy and enables chemoenzymatic processes for powerful and selective oxidative transformations.
- Betori, Rick C.,May, Catherine M.,Scheidt, Karl A.
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supporting information
p. 16490 - 16494
(2019/11/03)
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- Chiral Lithium Amido Aryl Zincates: Simple and Efficient Chemo- and Enantio-Selective Aryl Transfer Reagents
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An enantioselective aryl transfer is promoted using chiral tricoordinated lithium amido aryl zincates that are easily accessible reagents and whose chiral appendage is simply recovered for reuse. The arylation reaction is run in good yields (60 % average on twenty substrates) and high enantiomeric excesses (95 % ee average). This occurs whatever the ortho, meta, or para substituent borne by the substrate and a complete chemoselectivity is observed with respect to the aldehyde function. Sensitive groups such as nitriles, esters, ketones, and enolisable substrates resist to the action of the ate reagent, warranting a large scope to this methodology.
- Chaumont-Olive, Pauline,Rouen, Mathieu,Barozzino-Consiglio, Gabriella,Ben Abdeladhim, Amel,Maddaluno, Jacques,Harrison-Marchand, Anne
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supporting information
p. 3193 - 3197
(2019/01/25)
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- 4-Methyltetrahydropyran (4-MeTHP): Application as an Organic Reaction Solvent
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4-Methyltetrahydropyran (4-MeTHP) is a hydrophobic cyclic ether with potential for industrial applications. We herein report, for the first time, a comprehensive study on the performance of 4-MeTHP as an organic reaction solvent. Its broad application to organic reactions includes radical, Grignard, Wittig, organometallic, halogen-metal exchange, reduction, oxidation, epoxidation, amidation, esterification, metathesis, and other miscellaneous organic reactions. This breadth suggests 4-MeTHP can serve as a substitute for conventional ethers and harmful halogenated solvents. However, 4-MeTHP was found incompatible with strong Lewis acids, and the C?O bond was readily cleaved by treatment with BBr3. Moreover, the radical-based degradation pathways of 4-MeTHP, THP and 2-MeTHF were elucidated on the basis of GC-MS analyses. The data reported herein is anticipated to be useful for a broad range of synthetic chemists, especially industrial process chemists, when selecting the reaction solvent with green chemistry perspectives.
- Kobayashi, Shoji,Tamura, Tomoki,Yoshimoto, Saki,Kawakami, Takashi,Masuyama, Araki
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p. 3921 - 3937
(2019/11/11)
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- Diaryl hydroxylamines as pan or dual inhibitors of indoleamine 2,3-dioxygenase-1, indoleamine 2,3-dioxygenase-2 and tryptophan dioxygenase
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Tryptophan (Trp) catabolizing enzymes play an important and complex role in the development of cancer. Significant evidence implicates them in a range of inflammatory and immunosuppressive activities. Whereas inhibitors of indoleamine 2,3-dioxygenase-1 (IDO1) have been reported and analyzed in the clinic, fewer inhibitors have been described for tryptophan dioxygenase (TDO) and indoleamine 2,3-dioxygenase-2 (IDO2) which also have been implicated more recently in cancer, inflammation and immune control. Consequently the development of dual or pan inhibitors of these Trp catabolizing enzymes may represent a therapeutically important area of research. This is the first report to describe the development of dual and pan inhibitors of IDO1, TDO and IDO2.
- Winters, Maria,DuHadaway, James B.,Pham, Khoa N.,Lewis-Ballester, Ariel,Badir, Shorouk,Wai, Jenny,Sheikh, Eesha,Yeh, Syun-Ru,Prendergast, George C.,Muller, Alexander J.,Malachowski, William P.
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supporting information
p. 455 - 464
(2018/11/25)
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- Development of Ferrocene-Based Diamine-Phosphine-Sulfonamide Ligands for Iridium-Catalyzed Asymmetric Hydrogenation of Ketones
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A series of air-stable, easily accessible tridentate ferrocene-based diamine-phosphine sulfonamide (f-diaphos) ligands were successfully developed for iridium-catalyzed asymmetric hydrogenation of ketones. The f-diaphos ligands exhibited excellent enantioselectivity and superb reactivity in Ir-catalyzed asymmetric hydrogenation of ketones (for arylalkyl ketones, (S)-selectivity, up to 99.4% ee, and 100 000 TON; for diaryl ketones, (R)-selectivity, up to 98.2% ee, and 10 000 TON). This protocol could be easily conducted on gram scale, thereby providing a chance to various drugs.
- Ling, Fei,Nian, Sanfei,Chen, Jiachen,Luo, Wenjun,Wang, Ze,Lv, Yaping,Zhong, Weihui
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p. 10749 - 10761
(2018/09/06)
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- Chiral-at-metal iridium complex for efficient enantioselective transfer hydrogenation of ketones
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A bis-cyclometalated iridium(iii) complex with metal-centered chirality catalyzes the enantioselective transfer hydrogenation of ketones with high enantioselectivities at low catalyst loadings down to 0.002 mol%. Importantly, the rate of catalysis and enantioselectivity are markedly improved in the presence of a pyrazole co-ligand. The reaction is proposed to proceed via an iridium-hydride intermediate exploiting metal-ligand cooperativity (bifunctional catalysis).
- Tian, Cheng,Gong, Lei,Meggers, Eric
-
supporting information
p. 4207 - 4210
(2016/03/19)
-
- Aluminum Monohydride Catalyzed Selective Hydroboration of Carbonyl Compounds
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The well-defined aluminum monohydride compound [{(2,4,6-Me3-C6H2)NC(Me)}2(Me)(H)]AlH·(NMe2Et) (1) catalyzes hydroboration of a wide range of aldehydes and ketones under mild reaction conditions. Moreover, compound 1 displayed chemoselective hydroboration of aldehydes over ketones at rt.
- Jakhar, Vineet Kumar,Barman, Milan Kr.,Nembenna, Sharanappa
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p. 4710 - 4713
(2016/09/28)
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- Synthesis of new benzimidazolium salts and their application in the asymmetric arylation of aldehydes
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A series of novel chiral benzimidazolium salts, the precursor of N-heterocyclic carbene ligands, were designed and synthesized from 1,2-dibromobenzene. In situ prepared corresponding carbenes were tested in asymmetric Rh-catalyzed arylation of aromatic aldehydes, affording chiral diarylmethanols with high yields and moderate enantioselectivities.
- He, Wei-Ping,Zhou, Bi-Hui,Zhou, Ya-Li,Li, Xiang-Rong,Fan, Li-Mei,Shou, Hao-Wen,Li, Jie
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supporting information
p. 3152 - 3155
(2016/07/06)
-
- Coupling of aromatic aldehydes with aryl halides in the presence of nickel catalysts with diazabutadiene ligands
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Nickel catalysts with diazabutadiene ligands promote cross-coupling of benzaldehydes with aryl halides in the presence of zinc as reducing agent, which leads to the corresponding benzhydrols and benzophenones. The benzophenone percentage considerably increases when lithium chloride additive is used.
- Asachenko,Valaeva,Kudakina,Uborsky,Izmer,Kononovich,Voskoboynikov
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p. 456 - 463
(2017/03/08)
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- Cobalt-catalyzed asymmetric hydroboration of aryl ketones with pinacolborane
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The highly enantioselective cobalt-catalyzed hydroboration reaction of aryl ketones with HBpin was developed using iminopyridine oxazoline ligands. Halides, amines, ethers, sulfides, esters and amides are well tolerated under the mild reaction conditions, demonstrating its synthetic advantage. Substituted diaryl ketones could also be hydroborated with high enantioselectivity.
- Guo, Jun,Chen, Jianhui,Lu, Zhan
-
supporting information
p. 5725 - 5727
(2015/03/30)
-
- Enantioselective addition of ArTi(OiPr)3 to aldehydes catalyzed by a titanium complex of an N-sulfonylated amino alcohol
-
Asymmetric additions of ArTi(OiPr)3 to aldehydes catalyzed by a titanium catalyst of N-sulfonylated amino alcohols were reported, and results showed that the chiral N-sulfonylated amino alcohol with two stereogenic centers could catalyze the asymmetric addition of ArTi(OiPr)3 to aldehydes to afford desired secondary alcohols in good yields with good to excellent enantioselectivities of up to 95% ee.
- Chang, Shih-Ju,Zhou, Shuangliu,Gau, Han-Mou
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p. 9368 - 9373
(2015/02/19)
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- Elemental step thermodynamics of various analogues of indazolium alkaloids to obtaining hydride in acetonitrile
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A series of analogues of indazolium alkaloids were designed and synthesized. The thermodynamic driving forces of the 6 elemental steps for the analogues of indazolium alkaloids to obtain hydride in acetonitrile were determined using an isothermal titration calorimeter (ITC) and electrochemical methods, respectively. The effects of molecular structure and substituents on the thermodynamic driving forces of the 6 steps were examined. Meanwhile, the oxidation mechanism of NADH coenzyme by indazolium alkaloids was examined using the chemical mimic method. The result shows that the oxidation of NADH coenzyme by indazolium alkaloids in vivo takes place by one-step concerted hydride transfer mechanism.
- Lei, Nan-Ping,Fu, Yan-Hua,Zhu, Xiao-Qing
-
supporting information
p. 11472 - 11485
(2015/12/04)
-
- Direct trifluoromethylthiolation of alcohols under mild reaction conditions: Conversion of R-OH into R-SCF3
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A direct process for the trifluoromethylthiolation of allylic and benzylic alcohols under mild conditions has been developed. A wide range of free alcohols underwent nucleophilic substitution in the presence of stable CuSCF3 and BF3·Et2O to give the corresponding products in good to excellent yields.
- Nikolaienko, Pavlo,Pluta, Roman,Rueping, Magnus
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supporting information
p. 9867 - 9870
(2014/08/18)
-
- AlIII-calix[4]arene catalysts for asymmetric Meerwein-Ponndorf-Verley reduction
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Chiral AlIII-calixarene complexes were investigated as catalysts for the asymmetric Meerwein-Ponndorf-Verley (MPV) reduction reaction when using chiral and achiral secondary alcohols as reductants. The most enantioselective catalyst consisted o
- Nandi, Partha,Solovyov, Andrew,Okrut, Alexander,Katz, Alexander
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p. 2492 - 2495
(2014/08/18)
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- Direct electrosynthesis of ketones from benzylic methylenes by electrooxidative C-H activation
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Electrify your chemistry! Direct electrosynthesis of ketones from benzylic methylenes in an undivided cell was realized in moderate to good yields (see scheme). In this electrosynthesis, electrons instead of conventional oxidants and catalysts are employed to make the reaction environmentally benign. Moreover, the reaction intermediate radical was detected by ESR spectroscopy and the reaction mechanism was clarified.
- Meng, Li,Su, Jihu,Zha, Zhenggen,Zhang, Li,Zhang, Zhenlei,Wang, Zhiyong
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supporting information
p. 5542 - 5545
(2013/05/23)
-
- CHIRAL CALIXARENES
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In various embodiments, this invention provides a modular approach to build chiral calixarene phosphite and phosphate ligands that appends the chirality of readily available chiral diols (e.g., BINOL, VANOL, VAPOL etc) via corresponding chlorophosphite or
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Page/Page column 26
(2012/09/22)
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- Preparation and catalytic performances of a molecularly imprinted RU-complex catalyst with an NH2 binding site on a SiO2 surface
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A catalyst surface with an active metal site, a shape-selective reaction space, and an NH2 binding site for o-fluorobenzophenone was designed and prepared by the molecular imprinting of a supported metal complex on a SiO2 surface. A ligand of a SiO2-supported Ru complex that has a similar shape to the product of o-fluorobenzophenone hydrogenation was used as a template. An NH2 binding site for o-fluorobenzophenone was spatially arranged on the wall of a molecularly imprinted cavity with a similar shape to the template. The structures of the SiO2-supported and molecularly imprinted Ru catalysts were characterized in a step-by-step manner by means of solid-state magic angle spinning (MAS) NMR, XPS, UV/Vis, N 2 adsorption, XRF, and Ru K-edge EXAFS. The molecularly imprinted Ru catalyst exhibited excellent shape selectivity for the transfer hydrogenation of benzophenone derivatives. It was found that the NH2 binding site on the wall of the molecularly imprinted cavity enhanced the adsorption of o-fluorobenzophenone, of which the reduction product was imprinted, whereas there was no positive effect in the case of o-methylbenzophenone, which cannot interact with the NH2 binding site through hydrogen bonding. Tailoring a pocket: A molecularly imprinted Ru-complex catalyst with an NH 2 binding site for o-fluorobenzophenone has been successfully designed and prepared on a SiO2 surface for shape-selective transfer hydrogenation (see scheme). Copyright
- Yang, Yong,Weng, Zhihuan,Muratsugu, Satoshi,Ishiguro, Nozomu,Ohkoshi, Shin-Ichi,Tada, Mizuki
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experimental part
p. 1142 - 1153
(2012/03/26)
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- CuII-catalyzed asymmetric hydrosilylation of diaryl- and aryl heteroaryl ketones: Application in the enantioselective synthesis of orphenadrine and neobenodine
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With certain amounts of sodium tert-butoxide and tert-butanol as additives, catalytic amounts of an inexpensive and easy-to-handle copper source Cu(OAc)2·H2O, a commercially available and air-stable non-racemic dipyridylphosphine ligand, as well as the stoichiometric desirable hydride donor polymethylhydrosiloxane (PMHS), formed a versatile in situ catalyst system for the enantioselective reduction of a broad spectrum of prochiral diaryl and aryl heteroarylketones in air, in high yields and with good to excellent enantioselectivities (up to 96 %). In particular, the practical viability of this process was evinced by its successful applications in the asymmetric synthesis of optically enriched potent antihistaminic drugs orphenadrine and neobenodine. Copyright
- Sui, Yao-Zong,Zhang, Xi-Chang,Wu, Jun-Wen,Li, Shijun,Zhou, Ji-Ning,Li, Min,Fang, Wenjun,Chan, Albert S. C.,Wu, Jing
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supporting information; experimental part
p. 7486 - 7492
(2012/07/27)
-
- METHOD FOR SYNTHESIS OF SECONDARY ALCOHOLS
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A method for synthesis of secondary alcohols is provided for pharmaceutical secondary alcohol by addition of organoboronic acids with aldehydes in presence of the cobalt ion and bidentate ligands as the catalyst. In addition, an enantioselective synthesis method for secondary alcohols is also herein provided in the present invention. The present invention has advantages in using less expensive cobalt ion and commercially available chiral ligands as the catalyst, wide scope of organoboronic acids and aldehydes compatible with this catalytic reaction and achieving excellent yields and/or enantiomeric excess.
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Page/Page column 2
(2012/06/16)
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- MPV reduction using AlIII-calix[4]arene Lewis acid catalysts: Molecular-level insight into effect of ketone binding
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Catalytic Meerwein-Ponndorf-Verley (MPV) reduction using Al III-calix[4]arene complexes is investigated as a model system that requires the bringing together of two different chemical species, ketone and alkoxide, within a six-membered transition state. Two-point versus one-point ketone binding is demonstrated to be the most salient feature that controls MPV catalysis rate. A 7.7-fold increase in rate is observed when comparing reactants consisting of a bidentate Cl-containing ketone and sterically and electronically similar but looser-binding ketones, which are substituted with H and F. The one-point and two-point nature of ketone binding for the various ketones investigated is independently assessed using a combination of structural data derived from single-crystal X-ray diffraction and DFT-based molecular modeling. Using MPV catalysis with inherently chiral calix[4]arenes, the effect of multiple point reactant binding on enantioselectivity is elucidated. A higher denticity of ketone binding appears to increase the sensitivity of the interplay between chiral active site structure and MPV reduction enantioselectivity.
- Nandi, Partha,Matvieiev, Yuriy I.,Boyko, Vyacheslav I.,Durkin, Kathleen A.,Kalchenko, Vitaly I.,Katz, Alexander
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experimental part
p. 42 - 49
(2011/12/13)
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- Preparation of surface molecularly imprinted Ru-complex catalysts for asymmetric transfer hydrogenation in water media
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Molecularly imprinted Ru-complex catalysts acting in water were prepared on a SiO2 surface by molecular imprinting of a SiO2- supported Ru-complex using organic polymers as surface matrix overlayers. (R)-1-(o-fluorophenyl)ethanol, which is one of the hydrogenated products of o-fluoroacetophenone, was imprinted on the supported Ru-complex as a template, and an active Ru-complex with a shape-selective reaction space (molecularly imprinted cavity) was prepared inside the wall of the hydrophobic organic polymer matrix overlayers. Structures of the SiO2-supported and molecularly imprinted Ru catalysts were characterized by means of solid-state NMR, XPS, XRF, ICP, UV/vis, XAFS, TGA, and SEM. The molecularly imprinted Ru catalysts exhibited fine shape selectivity and enantioselectivity for the asymmetric transfer hydrogenation of o-fluoroacetophenone and its derivatives.
- Weng, Zhihuan,Muratsugu, Satoshi,Ishiguro, Nozomu,Ohkoshi, Shin-Ichi,Tada, Mizuki
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experimental part
p. 2338 - 2347
(2011/05/04)
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- Structural influence of chiral tertiary aminonaphthol ligands on the asymmetric phenyl transfer to aromatic aldehydes
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A series of chiral tertiary aminonaphthol ligands were prepared from 2-naphthol, (S)-1-phenylethylamine, and aldehydes with diverse substituted groups. The results of asymmetric phenyl transfer to aromatic aldehydes catalyzed by these chiral ligands indicated that enantioselectivities were greatly influenced by the electronic and steric effects of the ligands. Copyright
- Wei, Hui,Yin, Lu,Luo, Haibin,Li, Xingshu,Chan, Albert S. C.
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experimental part
p. 222 - 227
(2012/03/27)
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- Cobalt-catalyzed addition reaction of organoboronic acids with aldehydes: Highly enantioselective synthesis of diarylmethanols
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Predicted outcomes: The addition reaction of organoboronic acids with aldehydes in the presence of K2CO3 catalyzed by CoI 2/ACHTUNGRE(R,R)-BDPP gives chiral secondary alcohols in excellent yields with 90-99 % enantiomeric excess (see scheme; (R,R)-BDPP = (2R,4R)-(+)-2,4-bis(diphenyl-phosphino)pentane). This method provides an alternative to prepare an R and S enantiomeric pair by using the same chiral ligand and allows the stereochemical outcome of the reaction to be predicted.
- Karthikeyan, Jaganathan,Jeganmohan, Masilamani,Cheng, Chien-Hong
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supporting information; experimental part
p. 8989 - 8992
(2010/10/02)
-
- Continuous flow enantioselective arylation of aldehydes with ArZnEt using triarylboroxins as the ultimate source of aryl groups
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A continuous flow system for the synthesis of enantioenriched diarylmethanols from aldehydes is described. The system uses an amino alcohol-functionalized polystyrene resin as the catalyst, and the arylating agent is conveniently prepared by transmetallation of triarylboroxins with diethylzinc.
- Rolland, Julien,Cambeiro, Xacobe C.,Rodriguez-Escrich, Carles,Pericas, Miquel A.
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experimental part
(2010/04/22)
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- FeCl3-catalyzed 1,2-addition reactions of aryl aldehydes with arylboronic acids
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(Chemical Equation Presented) A novel protocol for the 1,2-addition reactions of electron-deficient aryl aldehydes with arylboronic acids using an inexpensive and environmentally benign iron catalyst is reported. In the presence of FeCl3 and 2-
- Zou, Tao,Pi, Sha-Sha,Li, Jin-Heng
-
supporting information; experimental part
p. 453 - 456
(2009/07/11)
-
- Method for Asymmetric Hydrosilylation of Ketones
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Method of asymmetrically hydrosilylating substrates using catalysts having a ligand of the compound of the formula (I) wherein R is optionally substituted alkyl, cycloalkyl, aryl or heteroaryl;R′ is hydrogen, optionally substituted lower alkyl; andR″ is hydrogen, halogen, optionally substituted alkyl, hydroxy, amino (e.g., primary, secondary or tertiary), alkenyl; or an enantiomer thereof; or an enantiomeric mixture thereof with a transition metal. Particularly suitable reactions include the asymmetric hydrosilylation of ketones.
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Page/Page column 6
(2008/12/04)
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- Generation and suppression of 3-/4-functionalized benzynes using zinc ate base (TMP-Zn-ate): New approaches to multisubstituted benzenes
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We present full details of our new methods for preparing functionalized benzynes with lithium di-alkyl(2,2,6,6-tetramethylpiperidino)zincate (R 2Zn(TMP)Li) through deprotonative zincation as a key reaction. In this system, by choosing appropriate ligands for the zincate, either regioselective zincation of functionalized haloaromatics or the generation of substituted benzynes can be controlled in good yields with excellent chemoselectivity, using the same substrate. Zincation with tBu 2Zn(TMP)Li followed by electrophilic trapping or zincation with Me2Zn(TMP)Li followed by nucleophilic or diene trapping is shown to be a powerful tool for the chemoselective preparation of 1,2,3-/1,2,4- trisubstituted benzene derivatives. These methods offer far greater generality than previous methods for the synthesis of multifunctionalized benzenes. Computational/theoretical studies of the reaction mechanism of this unique benzyne formation indicated that preferential coordination of the dialkylzinc moiety of zincate to halogen is the reason for the reduced activation energy of the elimination, that is, for the formation of the benzyne. The role of the ligands on Zn in accelerating/decelerating the elimination is also discussed.
- Uchiyama, Masanobu,Kobayashi, Yuri,Furuyama, Taniyuki,Nakamura, Shinji,Kajihara, Yumiko,Miyoshi, Tomoko,Sakamoto, Takao,Kondo, Yoshinori,Morokuma, Keiji
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p. 472 - 480
(2008/10/09)
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- Practical implications of boron-to-zinc transmetalation for the catalytic asymmetric arylation of aldehydes
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(Chemical Equation Presented) Faster than believed: Transmetalation from aryl boronic acids and triaryl boroxines to diethylzinc takes place within minutes following a two-step, low-energy pathway (see picture), according to density functional calculations and reaction microcalorimetry measurements. The experimental conditions for a practical, atom-economical, and highly enantioselective catalytic arylation of a variety of aldehydes have been developed from these data.
- Jimeno, Ciril,Sayalero, Sonia,Fjermestad, Torstein,Colet, Gisela,Maseras, Feliu,Pericas, Miquel A.
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p. 1098 - 1101
(2008/09/20)
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- Palladium-catalyzed 1,2-addition of potassium aryl- and alkenyltrifluoroborates to aldehydes using thioether-imidazolinium carbene ligands
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(Chemical Equation Presented) Palladium-catalyzed 1,2-addition of potassium aryl- and alkenyltrifluoroborates to aldehydes using thioether- imidazolinium carbene ligands proceeded readily under aqueous conditions. This process tolerated a diverse range of potassium trifluoroborate salts and aldehydes, giving a variety of carbinol derivatives with good to excellent yields.
- Kuriyama, Masami,Shimazawa, Rumiko,Enomoto, Terumichi,Shirai, Ryuichi
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p. 6939 - 6942
(2008/12/22)
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- Chloroform is not solvent but activator for cobalt complex catalyst of enantioselective borohydride reduction
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For the enantioselective borohydride reduction of carbonyl compounds catalyzed by the optically active ketoiminatocobalt complexes, chloroform has been employed as a unique solvent for achieving a high enantioselectivity, whereas it was found that a catal
- Kokura, Ai,Tanaka, Saiko,Teraoka, Haruna,Shibahrara, Atsushi,Ikeno, Taketo,Nagata, Takushi,Yamada, Tohru
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- Nickel-catalyzed 1,2-addition of arylboroxines to aromatic aldehydes
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Development of Ni-Et-Duphos-catalyzed 1,2-addition of arylboroxines to aromatic aldehydes is described. The dramatic effect of boron reagent and phosphine ligand is observed. This method with a phosphine ligand allows asymmetric arylation of aromatic aldehydes (up to 78% ee).
- Arao, Takafumi,Kondo, Kazuhiro,Aoyama, Toyohiko
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p. 4115 - 4117
(2008/02/03)
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- Catalytic enantioselective borohydride reduction of Ortho-fluorinated benzophenones
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In the presence of the optically active ketoiminatocobalt(II) complexes, the enantioselective borohydride reduction of benzophenones was successfully completed. The fluorine atom on the ortho position of the benzophenone and aryl ketones proved effective for obtaining high enantioselectivities. The combined use of modified lithium borohydride afforded the corresponding benzhydrols and arylcarbinols in high yield and high enantioselectivity (88-96% ee).
- Kokura, Ai,Tanaka, Saiko,Ikeno, Taketo,Yamada, Tohru
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p. 3025 - 3027
(2007/10/03)
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- Highly enantioselective phenyl transfer to aryl aldehydes catalyzed by easily accessible chiral tertiary aminonaphthol
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(Chemical Equation Presented) A new chiral tertiary aminonaphthol ligand 3b served as a highly efficient ligand for the asymmetric catalytic phenyl transfer to aromatic aldehydes and a variety of chiral diarylmethanols was prepared in high ee values (ee up to 99%) and chemical yields. The straightforward syntheses of both 3b and its enantiomer provide an excellent opportunity for large-scale applications.
- Ji, Jian-Xin,Wu, Jing,Au-Yeung, Terry T.-L.,Yip, Chiu-Wing,Haynes, Richard K.,Chan, Albert S. C.
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p. 1093 - 1095
(2007/10/03)
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- Polystyrene-supported amino alcohol ligands for the heterogeneous asymmetric addition of phenyl zinc reagents to aldehydes
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A family of polystyrene-supported amino alcohols, characterized by a high catalytic activity in alkyl transfer from zinc to formyl groups has been successfully tested in the enantioselective addition of phenyl zinc reagents to aldehydes to afford chiral diarylmethanols. Enantioselectivities higher than 90% (mean ee 90.5%; eight examples) are recorded with aromatic aldehydes in what represents the first successful use of heterogeneous, polymeric reagents for enantiocontrol in the phenylation of aldehydes.
- Castellnou, David,Fontes, Montserrat,Jimeno, Ciril,Font, Daniel,Solà, Lluís,Verdaguer, Xavier,Pericàs, Miquel A.
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p. 12111 - 12120
(2007/10/03)
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- CHIRAL TERTIARY AMINOALKYLNAPHTHOLS
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The invention relates to the compounds of formula: (I) which are as defined in the specification. Their use as chiral ligands in catalytic aryl transfer reactions to aromatic aldehydes is also described.
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Page/Page column 13; 16-17
(2008/06/13)
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- NITROGENOUS CYCLIC KETONE DERIVATIVE, PROCESS FOR PRODUCING THE SAME, AND USE
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A novel compound represented by the formula (I): wherein rings A and B each represents an optionally substituted aromatic ring, or rings A and B may be bonded to each other through linking between bonds or substituents thereof to form a ring; ring C represents a nitrogenous saturated heterocycle optionally having one or more substituents besides the oxo (provided that 2,3-dioxopyrrolidine ring is excluded); R1 represents hydrogen, an optionally substituted hydrocarbon group, or an optionally substituted heterocyclic group; and-------- indicates a single bond or a double bond. It has high antagonistic activity against a tachykinin receptor, especially an SP receptor.
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- 2-Piperidino-1,1,2-triphenylethanol: A Highly Effective Catalyst for the Enantioselective Arylation of Aldehydes
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Here we report the use of 2-piperidino-1,2,2-triphenylethanol (5) as an outstanding catalyst for the ligand-catalyzed arylation of aldehydes. The use of 5 and a 2/1 mixture of Et2Zn/Ph2Zn provided the corresponding chiral diarylcarbinols with enantiomeric excess of up to 99% ee. The effect of temperature on the reaction enantioselectivity was studied and the inversion temperature (Tinv) was determined to be 10 °C for reaction with p-tolylaldehyde. Most remarkably, lowering the amount of catalyst (5) to 0.5 mol % still afforded excellent levels of enantiocontrol (93.7% ee). Kinetics of the catalyzed and uncatalyzed arylation of aldehydes was studied by means of in situ FT-IR. The background uncatalyzed addition rates to p-tolylaldehyde when using pure Ph2Zn and Et2Zn/Ph 2-Zn (2/1) suggest that in the latter case a mixed zinc species forms (EtPhZn) minimizing the undesired nonselective addition. Formation of EtPhZn was modeled at the DFT calculation level. A four-center TS (TS-V) corresponding to the Et/Ph scrambling was localized along with two dimers (D-IV and D-VI). The model supports the hypothesis that Et/Ph exchange is a kinetically facile process. Gas evolution experiments during the formation of the active catalyst showed that the formation of an active site with a ONZn-Et (10) moiety is kinetically favored over ONZn-Ph (11). Finally, the phenyl transfer to benzaldehyde was modeled at the PM3(tm) level through anti and syn 5/4/4 tricyclic TS structures for both 10 and 11. The model could correctly predict the sense and selectivity of the overall process and predicted that 11 should be more selective than 10.
- Fontes, Montserrat,Verdaguer, Xavier,Sola, Lluis,Pericas, Miquel A.,Riera, Antoni
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p. 2532 - 2543
(2007/10/03)
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- BENZENE DERIVATIVES,PROCESS FOR PREPARING THE SAME AND USE THEREOF
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Novel benzene derivatives represented by the formula (I) : wherein R1, R4 and R6 each independently represents a hydrogen atom, a halogen atom or a hydrocarbon group, R2 represents a hydrocarbon group or a heterocyclic group, R3 represents a hydrocarbon group, NR7'R7 or OR8 (wherein R7' represents a hydrogen atom or a hydrocarbon group, R7 represents a non-aromatic group, or R7' and R7 may form a ring with the adjacent nitrogen atom, and R8 represents a hydrocarbon group or a heterocyclic group), R5 represents a hydrocarbon group or a heterocyclic group (except for a quinolyl group), R5' represents a hydrogen atom, or a hydrocarbon group, or R5 and R5' may form a ring with the adjacent nitrogen atom, and R5" represents a hydrogen atom or a hydrocarbon group, which have vanilloid receptor agonist activity and are useful as a drug such as an analgesic and an agent for preventing and/or treating urinary frequency and/or urinary incontinence.
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- Chiral [RuCl2(dipyridylphosphane)(1,2-diamine)] catalysts: Applications in asymmetric hydrogenation of a wide range of simple ketones
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The dipyridylphosphane/diamine - Ru complex combined with tBuOK in 2-propanol acts as a very effective catalyst system for the enantioselective hydrogenation of a diverse range of simple ketones including heteroaromatic ketones, substituted benzophenones, alkenyl ketones, and cyclopropyl ketones. The combination of desirable features, such as quantitative chemical yields within hours, broad substrate scope, excellent enantioselectivities (up to 99%), and high substrate-to-catalyst ratios, among others, makes the present catalyst system of high practical interest.
- Wu, Jing,Ji, Jian-Xin,Guo, Rongwei,Yeung, Chi-Hung,Chan, Albert S. C.
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p. 2963 - 2968
(2007/10/03)
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- Generation of functionalized asymmetric benzynes with TMP-zincates. Effects of ligands on selectivity and reactivity of zincates
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We have developed new methods for preparing functionalized benzynes through deprotonative zincation as a key reaction using R2Zn(TMP)Li, and we also describes dramatic ligand effects on the benzyne formation. Deprotonative zincation of various meta-substituted bromobenzenes with Me2Zn(TMP)Li proved effective for the one-pot generation of various 3-functionalized benzynes, particularly those electrophilic substituents such as ester, amide, and cyano. On the other hand, zincation with tBu2Zn(TMP)Li, followed by electrophilic trapping (with I2) proved a powerful tool for the preparation of 1,2,3-trisubstituted aromatic compounds.8 The resultant 1,2,3-trisubstituted benzenes are available as precursors for generation of 3-substituted benzynes by halogen-zinc exchange reactions with Me3ZnLi. These methods offer far greater generality than previous methods for the synthesis of functionalized asymmetric benzynes, and should be of value in new syntheses of various natural products and functional materials. In addition, these results underline the utility of spectator ligands on the central metal of ate complexes as a tunable functionality in the development of new ate complex-promoted reactions. Copyright
- Uchiyama, Masanobu,Miyoshi, Tomoko,Kajihara, Yumiko,Sakamoto, Takao,Otani, Yuko,Ohwada, Tomohiko,Kondo, Yoshinori
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p. 8514 - 8515
(2007/10/03)
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