- Trimethylstannylvinyl cuprates - - generation and 1, 4- conjugate addition to α,β - unsaturated ketones
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A new convenient route to the bis (trimethylstannylvinyl) cuprate reagent 6 is described. Its addition to α,β-unsaturated ketones has been compared with other mixed cuprates.
- Pereira, Oswy Z.,Chan T
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- Models for the reactive states of homocuprates: Syntheses, structures and reactivities of [Cu2Li2Mes4] and [Cu 3LiMes4]
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The synthesis and characterisation of two novel tetranuclear and thermally-stable lithium arylcuprates, [Cu2Li2Mes 4] and [Cu3LiMes4], are reported and [Cu 3LiMes4] is shown to be a highly active promoter for the 1,4-addition of organolithiums to enones. The Royal Society of Chemistry.
- Davies, Robert P.,Hornauer, Stefan,White, Andrew J. P.
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- Composes organomanganeux XXI. Reaction d'un compose organomanganeux avec une enone conjuguee: influence d'un acide de Lewis, d'un sel de fer ou d'un sel de nickel
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The reaction of organomanganese reagents with α,β-ethylenic ketones has been performed in the presence of various Lewis acids or metallic salts (Ni, Fe) in order to favour the formation of the conjugate addition product.The sole Lewis acid which gas given
- Cahiez, Gerard,Alami, Mouad
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- It's on lithium! An answer to the recent communication which asked the question: 'If the cyano ligand is not on copper, then where is it?'
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In this paper we answer the question recently posed by Lipshutz and James (see title), and we present a mechanism which explains why the cuprates prepared from CuCN have a greater product-forming ability in many reactions.
- Bertz, Steven H.,Miao, Guobin,Eriksson, Magnus
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- Counterion Enhanced Organocatalysis: A Novel Approach for the Asymmetric Transfer Hydrogenation of Enones
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We present a novel strategy for organocatalytic transfer hydrogenations relying on an ion-paired catalyst of natural l-amino acids as main source of chirality in combination with racemic, atropisomeric phosphoric acids as counteranion. The combination of a chiral cation with a structurally flexible anion resulted in a novel chiral framework for asymmetric transfer hydrogenations with enhanced selectivity through synergistic effects. The optimized catalytic system, in combination with a Hantzsch ester as hydrogen source for biomimetic transfer hydrogenation, enabled high enantioselectivity and excellent yields for a series of α,β-unsaturated cyclohexenones under mild conditions. Moreover, owing to the use of readily available and chiral pool-derived building blocks, it could be prepared in a straightforward and significantly cheaper way compared to the current state of the art.
- Scharinger, Fabian,Márk Pálv?lgyi, ádám,Zeindlhofer, Veronika,Schnürch, Michael,Schr?der, Christian,Bica-Schr?der, Katharina
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p. 3776 - 3782
(2020/06/22)
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- CuI-Catalysed Enantioselective Alkyl 1,4-Additions to (E)-Nitroalkenes and Cyclic Enones with Phosphino-Oxazoline Ligands
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Catalytic enantioselective conjugate additions of simple alkyl groups to nitroalkenes or cyclic enones that result in the formation of tertiary C–C bonds are described. For these stereoselective addition reactions, new chiral phosphino-oxazoline ligands w
- Shin, Minkyeong,Gu, Minji,Lim, Sung Soo,Kim, Min-Jae,Lee, JuHyung,Jin, HyeongGyu,Jang, Yun Hee,Jung, Byunghyuck
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p. 3122 - 3130
(2018/07/06)
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- Synthesis of the PMB ether of 5,6-epoxyisoprostane E2 through aldol reaction of the α-bromocyclopentanone
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5,6-Epoxyisoprostane E2 was synthesized via bromohydrination of the cyclopentene and aldol reaction of the α-bromocyclopentanone with the epoxyaldehyde. High regioselectivity in the bromohydrination was attained with recrystallized NBS and pyridine in aqu
- Kawashima, Hidehisa,Kobayashi, Yuichi
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p. 2598 - 2601
(2014/06/09)
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- A convenient catalytic asymmetric conjugate addition reaction to enones using alkylzirconium reagents
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Alkylzirconium reagents undergo highly enantioselective copper-catalysed 1,4-addition reaction to cyclic enones. These reactions use alkylmetal species generated in situ from alkenes and the Schwartz reagent, and do not require premade organometallic reag
- Maksymowicz, Rebecca M.,Sidera, Mireia,Roth, Philippe M. C.,Fletcher, Stephen P.
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supporting information
p. 2662 - 2668
(2013/10/21)
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- Chiral hetero- and carbocyclic compounds from the asymmetric hydrogenation of cyclic alkenes
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Several types of chiral hetero- and carbocyclic compounds have been synthesized by using the asymmetric hydrogenation of cyclic alkenes. N,P-Ligated iridium catalysts reduced six-membered cyclic alkenes with various substituents and heterofunctionality in good to excellent enantioselectivity, whereas the reduction of five-membered cyclic alkenes was generally less selective, giving modest enantiomeric excesses. The stereoselectivity of the hydrogenation depended more strongly on the substrate structure for the five- rather than the six-membered cyclic alkenes. The major enantiomer formed in the reduction of six-membered alkenes could be predicted from a selectivity model and isomeric alkenes had complementary enantioselectivity, giving opposite optical isomers upon hydrogenation. The utility of the reaction was demonstrated by using it as a key step in the preparation of chiral 1,3-cis-cyclohexane carboxylates. Copyright
- Verendel, J. Johan,Li, Jia-Qi,Quan, Xu,Peters, Byron,Zhou, Taigang,Gautun, Odd R.,Govender, Thavendran,Andersson, Pher G.
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supporting information; experimental part
p. 6507 - 6513
(2012/06/29)
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- Hydroxy-amide functionalized azolium salts for Cu-catalyzed asymmetric conjugate addition: Stereocontrol based on ligand structure and copper precatalyst
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A series of hydroxy-amide functionalized azolium salts have been designed and synthesized for Cu-catalyzed asymmetric conjugate addition reaction. The (CH2)2-bridged hydroxy-amide functionalized azolium ligand precursors 2, in addition to the previously reported CH2-bridged azolium salts 1, have been prepared from readily available enantiopure β-amino alcohols. The combination of a Cu species with 1 or 2 efficiently promoted the 1,4-addition reaction of cyclic enones with dialkylzincs. For example, the reaction of 2-cyclohepten-1-one (17) with Bu2Zn in the presence of catalytic amounts of Cu(OTf)2 and 1 gave (S)-3-butylcycloheptanone (20) in 99% yield and 96% ee. On the other hand, when the reaction was carried out under the influence of Cu(OTf)2 combined with 2, (R)-20 in preference to (S)-20 was obtained in 98% yield and 80% ee. In this manner, the enantioselecvity was switched by controlling the structure of chiral ligand. Additionally, the reversal of enantioselectivity was also achieved by changing the Cu precatalyst from Cu(OTf)2 to Cu(acac)2 with the same ligand. The combination of Cu(acac) 2 with CH2-bridged azolium salt 1 in the reaction of 17 with Bu2Zn led to formation of (R)-20 as a major product in 55% yield and 80% ee. This result was in contrast to the Cu(OTf)2/1 catalytic system, where the 1,4-adduct with opposite configuration was obtained. Moreover, use of the Cu(acac)2/2 catalytic system produced (S)-20, while (R)-20 was formed by the Cu(OTf)2/2 catalytic system. Thus, it was found that either varying the linker of the chiral ligands or changing the counterion of Cu species between a OTf and acac ligand initially on the metal led to dual enantioselective control in the 1,4-addition reaction.
- Shibata, Naoatsu,Yoshimura, Misato,Yamada, Haruka,Arakawa, Ryuichi,Sakaguchi, Satoshi
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experimental part
p. 4079 - 4086
(2012/06/04)
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- Ligand design for dual enantioselective control in Cu-catalyzed asymmetric conjugate addition of R2Zn to cyclic enone
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A new chiral N-heterocyclic carbene (NHC) ligand derived from a natural α-aminoester has been designed and synthesized. The coupling of N-methylbenzimidazole with an α-chloroacetamide derivative, which was prepared from chloroacetyl chloride and (S)-serin
- Yoshimura, Misato,Shibata, Naoatsu,Kawakami, Miaki,Sakaguchi, Satoshi
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experimental part
p. 3512 - 3518
(2012/06/04)
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- Catalytic enantioselective conjugate addition of Grignard reagents to cyclic enones using C1-1,1′-bisisoquinoline-based chiral ligands
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New highly constrained chiral C1-1,1′-bisisoquinoline ligands were examined in the enantioselective conjugate addition of Grignard reagents to cyclohexenone and cyclopentenone. The desired 1,4-adducts were obtained in excellent yield and moderate enantiomeric excess (up to 35%). Copyright Taylor & Francis Group, LLC.
- Qi, Gao,Judeh, Zaher M.A.
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experimental part
p. 1585 - 1592
(2012/05/04)
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- Preparation and characterization of new C2- and C 1-symmetric nitrogen, oxygen, phosphorous, and sulfur derivatives and analogs of TADDOL. part i
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The chloro alcohols 4-6 derived from TADDOLs (=α,α, α′,α′-tetraaryl-1,3-dioxolan-4,5-dimethanols) are used to prepare corresponding sulfanyl alcohols, ethers, and amines (Scheme 1 and Table 1). The dithiol analog of TADDOL and derivatives thereof, 45-49,
- Pichota, Arkadius,Gramlich, Volker,Beck, Albert K.,Seebach, Dieter
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experimental part
p. 1239 - 1272
(2012/09/21)
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- A new C2-symmetric azolium compound for Cu-catalyzed asymmetric conjugate addition of R2Zn to cyclic enone
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A new chiral N-heterocyclic carbene (NHC) ligand was designed. Thus, an efficient synthetic route to C2-symmetric bis(hydroxyamide)- functionalized benzimidazolium salts from chiral β-amino alcohols was developed. The combination of Cu(OTf)sub
- Harano, Ayako,Sakaguchi, Satoshi
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experimental part
p. 61 - 67
(2011/02/16)
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- Enantioselective copper-catalyzed 1,4-addition of dialkylzincs to enones followed by trapping with allyl iodide derivatives
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Enantioselective copper-catalyzed 1,4-addition of dialkylzincs to enones proceeded in the presence of 0.1 mol% of Cu(OTf)2 and 0.25 mol% of an N,N,P-ligand containing a quinoline moiety to afford the corresponding conjugated adducts in 99%ee. The intermediate zinc enolates were trapped with substituted allyl iodides to give disubstituted ketones with high diastereoselectivity and enantioselectivity.
- Kawamura, Kenjiro,Fukuzawa, Hitomi,Hayashi, Masahiko
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experimental part
p. 640 - 647
(2011/08/06)
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- Enders SAMP-hydrazone as traceless auxiliary in the asymmetric 1,4-addition of cuprates to enones
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Conjugate additions of Gilman cyanocuprates to (5)-N-amino-2- (methoxymethyl)pyrrolidine (SAMP)-hydrazones 4, 5 derived from cyclic and acyclic α,β-unsaturated ketones were investigated. A protocol utilizing copper(II) sulfate/ammonium chloride was evolved, which allowed cleavage of SAMP (S)-1 under the hydrolysis and work-up conditions, followed by recovery of the auxiliary with ethylenediaminetetraacetic acid (EDTA). The enantioselectivity of cuprate additions was dominated for cyclic SAMP-hydrazones 4 by the cuprate alkyl substituent and the ring size, in the case of acyclic arylidene SAMP-hydrazones 5, however, by the nature of the aryl substituent. Electron-donating substituents gave poor enantiomeric excesses, whereas electron-withdrawing groups provided excellent ee values of 98-99%. The configuration of the new stereocenter was determined to be (R). Moreover, a reaction sequence was developed which integrates a tandem 1,4-addition/ methylation and traceless hydrolytic cleavage of the auxiliary (S)-1 in a one-pot reaction, resulting in enantiomerically pure methyl ketones 11-13, each of them with > 99% ee.
- Sammet, Karsten,Gastl, Christoph,Baro, Angelika,Laschat, Sabine,Fischer, Peter,Fettig, Ina
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supporting information; experimental part
p. 2281 - 2290
(2010/12/29)
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- Reversal of stereoselectivity in the Cu-catalyzed conjugate addition reaction of dialkylzinc to cyclic enone in the presence of a chiral azolium compound
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Reversal of enantioselectivity in a Cu-catalyzed asymmetric conjugate addition reaction of dialkylzinc to cyclic enone with use of the same chiral ligand was successfully achieved. The reaction of 2-cyclohexen-1-one (30) with Et2Zn catalyzed by
- Shibata, Naoatsu,Okamoto, Masaki,Yamamoto, Yuko,Sakaguchi, Satoshi
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experimental part
p. 5707 - 5715
(2010/10/21)
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- Ni(II)-catalyzed enantioselective conjugate addition of acetylenes to α,β-enones
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(Figure presented) Alkynylaluminum reagents undergo enantloselective conjugate addition to cyclic α,β-enones In the presence of chiral bisphosphine complexes of NI(II).
- Larlonov, Oleg V.,Corey
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supporting information; experimental part
p. 300 - 302
(2010/03/25)
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- Copper-catalyzed asymmetric conjugate addition with Grignard reagents and SimplePhos ligands
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Herein we report the copper-catalyzed asymmetric conjugate addition of Grignard reagents to cyclic and acyclic enones, with SimplePhos as chiral ligands. A variety of Grignard reagents can be added to a range of cyclic and acyclic enones, with moderate to good enantioselectivities (ee's up to 86%).
- Palais, Laetitia,Alexakis, Alexandre
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experimental part
p. 2866 - 2870
(2010/04/05)
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- A new approach to switching of enantioselectivity in NHC-Cu-catalyzed conjugate addition of alkylzincs to cyclic enones
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Conjugate addition of Et2Zn to 2-cyclohexen-1-one catalyzed by Cu(OTf)2 combined with an azolium salt derived from (S)-leucinol produced the corresponding (S)-adduct, while the use of Cu(acac)2 in combination with the same
- Okamoto, Masaki,Yamamoto, Yuko,Sakaguchi, Satoshi
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supporting information; experimental part
p. 7363 - 7365
(2010/06/13)
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- Conjugate addition reactions of N-carbamoyl-4-pyridones with organometallic reagents
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(Chemical Equation Presented) N-Carbamoyl-4-pyridones undergo conjugate addition reactions with organocuprates and organozincates to afford 2-substituted-2,3-dihydro-4-pyridones providing a direct synthetic approach to substituted piperidines and piperido
- Dieter, R. Karl,Guo, Fenghai
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experimental part
p. 3843 - 3848
(2009/09/25)
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- Novel N,N,P-tridentate ligands for the highly enantioselective copper-catalyzed 1,4-addition of dialkylzincs to enones
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(Chemical Equation Presented) Use of 0.25 mol % of the N,N,P-tridentate ligand containing the 2-quinolyl moiety (1 and 2) and 0.1 mol % of Cu(OTf) 2 enabled the enantioselective 1,4-addition of dialkylzincs to cyclic enones to produce 1,4-adduc
- Kawamura, Kenjiro,Fukuzawa, Hitomi,Hayashi, Masahiko
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supporting information; scheme or table
p. 3509 - 3512
(2009/05/07)
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- General method for the expedient synthesis of salt-free diorganozinc reagents using zinc methoxide
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The effect of counterions has a great impact on the solubility of magnesium salts in Et2O. By reacting Zn(OMe)2 with readily available Grignard reagents, it was possible to induce the complete precipitation of magnesium salts and then obtain salt-free dio
- Cote, Alexandre,Charette, Andre B.
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p. 2771 - 2773
(2008/10/09)
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- METHODS FOR PREPARING DIORGANOZINC COMPOUNDS
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There are provided methods for preparing the diorganozmc compounds of formula R2Zn (I or Ia), where R is a defined organic radical, and the two R groups can be the same or different The starting material is the zinc compound ZnX2 (II) or R2ZnX (IIa), where X is a defined anion and R2 is a defined organic radical. The zinc reagent of type II is combined with a Grignard reagent and also, when X is Cl or Br, with an alkali metal reagent (VI) to form the diorganozinc product (I or Ia). Also provided are methods for preparing the zinc alcoholates of formula Zn(OR1)2 by reaction of ZnX2, where X = Cl or Br, with an alkali metal reagent of the formula MOR1, where M = Na or K, and where R1 is a defined organic radical.
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Page/Page column 19-20
(2009/01/20)
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- Enantioselective hydrogenation of enones with a hydroformylation catalyst
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Use of a typical rhodium precatalyst for hydroformylation results in the enantioselective hydrogenation of cyclic enones with up to 90% ee. Extensive screening of chiral ligands reveals the simple ligand Chiraphos as the best ligand, so far. The hydrogenation shows high chemoselectivity. Exclusive formation of saturated, chiral b-branched ketones is observed. It is proposed that the catalyst follows a frustrated hydroformylation pathway ("monohydride-based mechanism") and differs by that from the classical cationic Schrock-Osborn type rhodium precatalysts ("dihydride-based mechanism") for enantioselective hydrogenation. The catalyst operates under neat conditions and is easily recyclable by simply distilling off the reaction mixture and treatment with syn gas prior to hydrogenation.
- Scheuermann Nee Taylor, Caroline J.,Jaekel, Christoph
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supporting information; experimental part
p. 2708 - 2714
(2009/10/06)
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- Enantioselective conjugate addition of dialkylzinc to cyclic enones catalyzed by chiral binaphthyldiamine-copper(I) complexes
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The enantioselective conjugate addition of dialkylzinc (R2Zn) to cyclic enones was examined using chiral binaphthyldiamine-copper(I) catalysts. Under the present reaction conditions, chiral C2-symmetric [RZn(II)]2-diamine-
- Hatano, Manabu,Asai, Takafumi,Ishihara, Kazuaki
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p. 8590 - 8594
(2008/03/30)
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- Hydride reduction of alpha, beta-unsaturated carbonyl compounds using chiral organic catalysts
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Nonmetallic, chiral organic catalysts are used to catalyze the 1,4-hydride reduction of an α,β-unsaturated carbonyl compound. The α,β-unsaturated carbonyl compound may be an aldehyde or cyclic ketone, and the hydride donor may be a dihydropyridine. The reaction is enantioselective, and proceeds with a variety of hydride donors, catalysts, and substrates. The invention also provides compositions effective in carrying out the 1,4-hydride addition of α,β-unsaturated carbonyl compounds.
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Page/Page column 25-26
(2008/06/13)
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- Organocatalytic transfer hydrogenation of cyclic enones
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The first enantioselective organocatalytic transfer hydrogenation of cyclic enones has been accomplished. The use of iminium catalysis has provided a new organocatalytic strategy for the enantioselective reduction of β,β-substituted α,β-unsaturated cycloalkenones, to generate β-stereogenic cyclic ketones. The use of imidazolidinone 4 as the asymmetric catalyst has been found to mediate the hydrogenation of a large class of enone substrates with tert-butyl Hantzsch ester serving as an inexpensive source of hydrogen. The capacity of catalyst 4 to enable enantioselective transfer hydrogenation of cycloalkenones has been extended to five-, six-, and seven-membered ring systems. The sense of asymmetric induction is in complete accord with the stereochemical model first reported in conjunction with the use of catalyst 4 for enantioselective ketone Diels-Alder reactions. Copyright
- Tuttle, Jamison B.,Ouellet, Stephane G.,MacMillan, David W. C.
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p. 12662 - 12663
(2008/02/05)
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- Novel compounds and their use in therapy
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Thiophenepyrimidinone compounds and their use in therapy, especially for use in the treatment and/or prevention of a steroid hormone dependent diseases or disorders, such as steroid hormone dependent diseases or disorders requiring inhibition of 17β-hydroxysteroid dehydrogenase enzymes.
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- Assessing the Substrate Selectivities and Enantioselectivities of Eight Novel Baeyer-Villiger Monooxygenases toward Alkyl-Substituted Cyclohexanones
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Genes encoding eight Baeyer-Villiger monooxygenases have recently been cloned from bacteria inhabiting a wastewater treatment plant. We have carried out a systematic investigation in which each newly cloned enzyme, as well as the cyclohexanone monooxygenase from Acinetobacter sp. NCIB 9871, was used to oxidize 15 different alkyl-substituted cyclohexanones. The panel of substrates included equal numbers of 2-, 3-, and 4-alkyl-substituted compounds to probe each enzyme's stereoselectivity toward a homologous series of synthetically important compounds. For all 4-alkyl-substituted cyclohexanones tested, enzymes were discovered that afforded each of the corresponding (S)-lactones in ≥98% ee. This was also true for the 2-alkyl-substituted cyclohexanones examined. The situation was more complex for 3-akyl-substituted cyclohexanones. In a few cases, single Baeyer-Villiger monooxygenases possessed both high regio- and enantioselectivities toward these compounds. More commonly, however, they showed only one type of selectivity. Nonetheless, enzymes with such properties might be useful as parts of a two-step bioprocess where an initial kinetic resolution is followed by a regioselective oxidation on the isolated, optically pure ketone.
- Kyte, Brian G.,Rouviere, Pierre,Cheng, Qiong,Stewart, Jon D.
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- GUANIDINE DERIVATIVES AND USE THEREOF AS NEUROPEPTIDE FF RECEPTOR ANTAGONISTS
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The invention relates to guanidine derivatives of formula (I) where: A = a chain of 3-c6 carbon atoms, one of which can be replaced by -N(R')- or -O- and R' = H or a substituent, where the ring skeleton only contains both double bonds of the thiazole component, the pharmaceutically-acceptable acid addition salts of basic compounds of formula (I), the pharmaceutically-acceptable salts of compounds of formula (I),, comprising acid groups, with bases, the pharmaceutically-acceptable esters of hydroxy or carboxyl group containing compounds of formula (I) and the solvates or hydrates thereof, which are partly known and partly novel and exhibit a neuropeptide FF receptor antagonist effect. The above are suitable for the treatment of pain and hyperalgesia, withdrawal symptoms in alcohol, psychotropic and nicotine dependencies, for improvement or cure of said dependencies, for regulation of insulin excretion, food intake, memory functions, blood pressure, electrolyte and energy management and for treatment of urinary incontinence. The above can be produced using generally used methods and processed to give medicaments.
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- Highly practical and enantioselective Cu-catalyzed conjugate addition of alkylzinc reagents to cyclic enones at ambient temperature
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(Matrix presented) A new ligand for Cu-catalyzed enantioselective additions of dialkylzincs to cyclic enones has been developed. In addition to providing good to excellent enantioselectivities with a range of cyclic enones and dialkylzincs, the ligand has several notworthy features: it can be readily prepared in just two steps, is an air-stable crystalline solid, and provides optimal performance at ambient temperature.
- Krauss, Isaac J.,Leighton, James L.
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p. 3201 - 3203
(2007/10/03)
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- Copper-catalyzed enantioselective conjugate addition of dialkylzinc reagents to enones with new peptidyl phosphane ligands
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Copper catalysts based on new peptidyl phosphane ligands have been developed for enantioselective conjugate additions of dialkylzinc reagents to cyclic enones. Enantioselectivities greater than 97% ee have been observed.
- Breit, Bernhard,Laungani, Andy Ch.
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p. 3823 - 3826
(2007/10/03)
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- Chiral lithiothiophenes as non-transferable ligands in organocuprate conjugate addition reactions
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Non-transferable carbon bound homochiral ligands have been developed for the asymmetric transfer of an alkyl or an aryl group to a prochiral α,β-unsaturated enone with copper reagents. These ligands are based on thiophene and chiral amino alcohols derived from L-proline and ephedrine.
- Ogle, Craig A.,Human, Jason B.
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p. 3281 - 3283
(2007/10/03)
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- Chiral diselenide ligands for the asymmetric copper-catalyzed conjugate addition of Grignard reagents to enones
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The copper-catalyzed conjugate addition of Grignard reagents to enones in the presence of chiral diselenide oxazoline ligands has been studied and found to provide good yields and useful levels of asymmetric induction.
- Braga, Antonio L,Silva, Sandra J.N,Lüdtke, Diogo S,Drekener, Roberta L,Silveira, Claudio C,Rocha, Joao B.T,Wessjohann, Ludger A
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p. 7329 - 7331
(2007/10/03)
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- Asymmetric 1,4-reductions of and 1,4-additions to enoates and related systems
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One aspect of the present invention relates to methods for the transition-metal-catalyzed asymmetric 1,4-addition of a nucleophile, e.g., hydride, to cyclic and acyclic enoates and enones. In certain embodiments of the methods of the present invention, th
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- Preparation and reactivity of cyanocuprates containing alkylseleno and alkyltelluro groups as non-transferable ligands
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Alkylseleno and alkyltelluro groups are efficient non-transferable ligands of cyanocuprates in 1,4-addition reactions to enones.
- Zinn, Fabiano K.,Ramos, Eduardo C.,Comasseto, Jo?o V.
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p. 2415 - 2417
(2007/10/03)
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- 1,4-Addition of diorganozincs to α,β-unsaturated ketones catalyzed by a copper(I)-sulfonamide combined system
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A mixture of CuCN and N-benzylbenzenesulfonamide catalyzes the 1,4- addition of dialkylzincs or diarylzincs (Cu: Zn = 1: 200 to 1: 10000) to α,β-unsaturated ketones to give, after aqueous workup, the corresponding β-substituted ketones in nearly quantitative yields. A range of cyclic enones having s-cis or s-trans geometries as well as conformationally flexible acyclic enones are usable as substrates. The ethyl group migrates more readily than the methyl and phenyl groups. CuOTf, CuO-t-C4H9, and mesitylcopper can be used in place of CuCN. The in situ-formed alkylzinc enolate, prior to aqueous workup, further undergoes an aldol reaction with aldehydes or Pd(0)-assisted coupling with allyl acetate, resulting in regio- controlled, vicinal carbacondensation products. A catalytic cycle is proposed on the basis of a kinetic study and a structural analysis of the zinc enolate product by NMR and molecular weight measurements.
- Kitamura, Masato,Miki, Takashi,Nakano, Keiji,Noyori, Ryoji
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p. 999 - 1014
(2007/10/03)
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- Isotope effects and the mechanism of chlorotrimethylsilane-mediated addition of cuprates to enones
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Kinetic isotope effects were determined for the chlorotrimethylsilane- mediated reactions of cyclohexenone with lithium dibutylcuprate in tetrahydrofuran and with lithium butyl(tert-butylethynyl)cuprate in ether. For the reaction in tetrahydrofuran, the observation of a significant carbonyl oxygen isotope effect (16k/17k = 1.018-1.019) and small olefinic carbon isotope effects (12k/13k = 1.003-1.008) is consistent with rate- limiting silylation of an intermediate π-complex. Theoretically predicted isotope effects for model reactions support this conclusion. Rate-limiting silylation is also supported by relative reactivity studies of chlorotrimethylsilane versus chlorodimethylphenylsilane. The absence of a significant butyl-group carbon isotope effect on product formation indicates that the cuprate butyl groups are nonequivalent in the intermediate leading to the product-determining step. In diethyl ether the isotope effects revert to values similar to those found previously in reactions of cyclohexenone with lithium dibutylcuprate in the absence of chlorotrimethylsilane, consistent with no change in the overall mechanism in this solvent. A mechanistic hypothesis for the differing effects of TMSCl with changes in solvent and substrate is presented.
- Frantz, Doug E.,Singleton, Daniel A.
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p. 3288 - 3295
(2007/10/03)
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- Enantioselective conjugate addition of organometallic reagents to cycloalkenones by the aid of chiral lactam-phosphine ligand
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The chiral lactam-phosphine ligand and copper salt mediated asymmetric conjugate addition reaction of butylmagnesium chloride and diethylzinc with cycloalkenones. Among phosphines examined, 5-((diphenylphosphino)methyl)-3,3- dimethylpyrrolidin-2-one (1) g
- Tomioka, Kiyoshi,Nakagawa, Yuichi
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- New copper chemistry, part 29: Re-evaluation of organocuprate reactivity: Logarithmic reactivity profiles for iodo- versus cyano-Gilman reagents in the reactions of organocuprates with 2-cyclohexenone and iodocyclohexane
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Iodo-Gilman reagents Me2-CuLi·LiI, Bu2CuLi·LiI, and BuThCu-Li·LiI and cyano-Gilman reagents (nee "higher order cyanocuprates" Me2Cu-Li·LiCN, Bu2CuLi·LiCN, and BuTh-CuLi·LiCN react with 2-cyclohexenone at various rates, which depend upon the R groups (Me, Bu, Th=thienyl), Li salt (LiI vs. LiCN), solvent (ether vs. THF), and amount of trimethylsilyl chloride (TMSCl) additive. The effect of the Li salt (CuI vs. CuCN precursor) is less than that of solvent or TMSCl. The butylcuprate-iodocyclohexane reaction has also been examined as a function of Li salt, solvent, and TMSCl additive, and similar effects are observed. The reactivity matrix R with elements ri,j is a convenient way to store and present a large amount of relative reactivity data. Entry ri,j is the ratio of the rate with reagent i to the rate with reagent j, which we approximate by using yields measured after a short time (4 s). The logarithmic reactivity profile (LRP) provides an efficient means for determining yields under conditions where such comparisons are valid. The results of a large number of 4-point LRPs and related reactions are tabulated and analyzed to provide a clearer picture of organocuprate reactivity.
- Bertz, Steven H.,Chopra, Anu,Eriksson, Magnus,Ogle, Craig A.,Seagle, Paul
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p. 2680 - 2691
(2007/10/03)
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- A new convenient procedure to prepare organomanganese reagents from organic halides and activated manganese
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A new method to obtain activated manganese metal, especially attractive for large scale preparative organic chemistry, is described. The key point is the use of 2-phenylpyridine as electron carrier to reduce manganese chloride by lithium. The active manganese thus obtained was used to prepare various organomanganese reagents from organic halides. The reactivity of these reagents has been studied (acylation, 1,2- or 1,4-addition, alkylation and alkenylation).
- Cahiez, Gerard,Martin, Arnaud,Delacroix, Thomas
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p. 6407 - 6410
(2007/10/03)
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- Neopentyl and neophyl groups: New nontransferable groups for organocopper and organozinc chemistry
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Neopentyl and Neophyl groups have been found to be excellent nontransferable groups for organozinc and organocopper chemistry. We have shown that mixed diorganozincs of the type FG-R-Zn(CH2CMe2R) can be used advantageously for the enantioselective addition to aldehydes. These mixed copper or zinc reagents are also found to be very efficient in the Michael addition to various activated alkenes.
- Lutz, Christian,Jones, Philip,Knochel, Paul
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p. 312 - 316
(2007/10/03)
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- C(1)-substituted menthol derivatives: Self-removing chiral auxiliaries for asymmetric conjugate additions to cycloalkenones
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C(1)-substituted (-)-menthone derivatives 3 were prepared by the stereoselective addition of the alkenyllithium reagents 9 to menthone (8) and subsequent acid catalyzed hydrolysis of the dioxolane protecting groups. Conjugate addition of cuprate reagents
- Funk, Raymond L.,Yang, Ge
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p. 1073 - 1074
(2007/10/03)
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- Catalytic enantioselective conjugate addition of Grignard reagents to cyclic α,β-unsaturated carbonyl compounds
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A catalytic asymmetric conjugate addition reaction of organocopper reagents, generated from copper salt, a chiral phosphine, and Grignard reagent, with cyclohexenone is highly dependent on the counter anion of copper species, solvents, Grignard reagents,
- Kanai, Motomu,Nakagawa, Yuichi,Tomioka, Kiyoshi
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p. 3843 - 3854
(2007/10/03)
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- An asymmetric conjugate addition reaction of lithium organocopper reagent controlled by a chiral amidophosphine
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Examination of the behaviors of the chiral amidophosphines 1-14 in the asymmetric conjugate addition reaction of lithium organocopper with chalcone and cycloalkenone revealed that the reaction efficiency is governed by many factors including copper salt, solvent, molecular ratio of copper and organolithium, and the structure of the substrate. The reaction with cycloalkenone gave the adduct in up to 94% ee under the stoichiometric conditions.
- Kanai, Motomu,Nakagawa, Yuichi,Tomioka, Kiyoshi
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p. 3831 - 3842
(2007/10/03)
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- Conjugate Michael additions with mixed diorganozincs
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Functionalised mixed alkyl(trimethylsilylmethyl)zinc reagents add efficiently to a wide variety of Michael acceptors in high yield and with exclusive 1,4-regioselectivity, without the need for transition metal catalysis. The trimethylsilylmethyl group behaves as a non-transferable group, and in no cases was transfer of this group observed.
- Jones, Philip,Kishan Reddy,Knochel, Paul
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p. 1471 - 1490
(2007/10/03)
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- An external chiral amidophosphine ligand for asymmetric conjugate addition of organocopper
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Two types of external, chiral amidophosphine ligands, 1-5, were prepared. Examination of their behavior in an asymmetric conjugate addition reaction of organocuprate revealed the possibility for steric tuning to realize high selectivity.
- Nakagawa, Yuichi,Kanai, Motomu,Nagaoka, Yasuo,Tomioka, Kiyoshi
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p. 10295 - 10307
(2007/10/03)
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- Synthesis and alkylation of cyclic α-sulfonimidoyl carbanions: Non- transferable chiral carbanionic ligands in copper-mediated enantioselective conjugate addition
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The cyclic sulfoximines 4a and 4b have been prepared from (+)-(S)-S- methyl-S-phenylsulfoximine (1). Deprotonation of 4a and 4b and alkylation of lithiosulfoximines Li-4a and Li-4b gave α-alkyl substituted sulfoximines 5a (89% de), 5b (90% de), 6a (≤98% de), 6b (≤98% de), 7b (≤98% de) and 8b (≤98% de). The configuration of 6b was determined by X-ray structure analysis. Consecutive treatment of 5b, 6b and 8b with BuLi and CF3CO2H gave epimers epi-5b (64% de), epi-6b (89% de) and epi-8b (81% de). α,α -Dialkyl substituted sulfoximines 9 (≤98% de) and epi-9 (≤98% de) were obtained by alkylation of Li-5b and Li-6b. Conjugate addition of cuprates 11-14, containing the acyclic sulfonimidoyl carbanions Ia-c, to cyclohex-2-en-1-one gave ketones 15 and 16 in good yields but with low asymmetric induction (8- 49% ee). However, conjugate addition of cuprates 19b, 20b, 21b and 22b, derived from the cyclic lithiosulfoximines Li-7b and Li-8b, to cyclopent-2- en-1-one, cyclohex-2-en-1-one and cyclohept-2-en-1-one gave ketones 15a-c, 23b and 24b with good to high asymmetric inductions (77-99% ee) in good yields. The bicyclic ketone 27 (79% ee) was prepared from cyclohex-2-en-1- one via 24b in three steps.
- Bo?hammer, Stephan,Gais, Hans-Joachim
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p. 919 - 927
(2007/10/03)
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- Novel tridentate diamino organomanganese(II) complexes as homogeneous catalysts in manganese(II)/copper(I) catalyzed carbon-carbon bond forming reactions
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The new, paramagnetic arylmanganese(II) complex Li[MnCl2(NCN)] (2, NCN [C6H3(CH2NMe2)2-2,6] -) has been obtained in high yield from the reaction of MnCl2 and [Li(NCN)]2 in a 2:1 molar ratio. In THF solution, 2 is likely an ionic species [Li(THF)n] [MnCl2(NCN)] (molecular weight determination and conductivity measurements), while magnetic measurements indicate that a high spin d5 manganese(II) center is present. Subsequent reaction of 2 with RLi afforded [MnR(NCN)] (R=Me (3a), n-Bu (3b)). Complex 2, using CuCl as a co-catalyst, is an effective catalyst system for cross-coupling of Grignard reagents with alkyl bromides and the 1,4-addition of organomagnesium halides to α,β-unsaturated ketones. No further additives or co-solvents are necessary. For both reactions a dramatic decrease in reaction times is observed when compared to standard manganese/copper systems. Alkyl bromides with unsaturated or heteroatom functionalities can be cross-coupled. Also, excellent reactivity towards normally unreactive β,β-disubstituted ketones has been observed in the 1,4-addition reaction.
- Donkervoort, Johannes G.,Vicario, Jose L.,Jastrzebski, Johann T.B.H.,Gossage, Robert A.,Cahiez, Gerard,Van Koten, Gerard
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