- Reaction of zirconacycles with 3-iodopropenoates and 3-iodocycloenones in the presence of CuCl: A new pathway for the formation of cyclopentadienes and spirocyclic compounds
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Formation of cyclic compounds from zirconacycles has been performed by a combination of Michael addition and coupling with an alkenyl iodide moiety in the presence of a stoichiometric amount of CuCl. The reaction of 3- iodopropenoates with various zircona
- Xi, Chanjuan,Kotora, Martin,Nakajima, Kiyohiko,Takahashi, Tamotsu
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Read Online
- Total Synthesis of (-)-Xylogranatopyridine B via a Palladium-Catalyzed Oxidative Stannylation of Enones
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We report a total synthesis of the pyridine-containing limonoid alkaloid (-)-xylogranatopyridine B in 11 steps from commercially available dihydrocarvone. The central pyridine ring was assembled by a late-stage fragment coupling approach employing a modified Liebeskind pyridine synthesis. One fragment was prepared by an allyl-palladium catalyzed oxidative enone β-stannylation, in which the key bimetallic β-stannyl palladium enolate intermediate undergoes a β-hydride elimination. This methodology also allowed introduction of alkyl and silyl groups to the β-position of enones.
- Schuppe, Alexander W.,Huang, David,Chen, Yifeng,Newhouse, Timothy R.
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supporting information
p. 2062 - 2066
(2018/02/19)
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- Chemo-Enzymatic Oxidative Rearrangement of Tertiary Allylic Alcohols: Synthetic Application and Integration into a Cascade Process
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A chemo-enzymatic catalytic system, comprised of Bobbitt's salt and laccase from Trametes versicolor, allowed the [1,3]-oxidative rearrangement of endocyclic allylic tertiary alcohols into the corresponding enones under an Oxygen atmosphere in aqueous media. The yields were in most cases quantitative, especially for the cyclopent-2-en-1-ol or the cyclohex-2-en-1-ol substrates without an electron withdrawing group (EWG) on the side chain. Transpositions of macrocyclic alkenols or tertiary alcohols bearing an EWG on the side chain were instead carried out in acetonitrile by using an immobilized laccase preparation. Dehydro-Jasmone, dehydro-Hedione, dehydro-Muscone and other fragrance precursors were directly prepared with this procedure, while a synthetic route was developed to easily transform a cyclopentenone derivative into trans-Magnolione and dehydro-Magnolione. The rearrangement of exocyclic allylic alcohols was tested as well, and a dynamic kinetic resolution was observed: α,β-unsaturated ketones with (E)-configuration and a high diastereomeric excess were synthesized. Finally, the 2,2,6,6-tetramethyl-1-piperidinium tetrafluoroborate (TEMPO+BF4?)/laccase catalysed oxidative rearrangement was combined with the ene-reductase/alcohol dehydrogenase cascade process in a one-pot three-step synthesis of cis or trans 3-methylcyclohexan-1-ol, in both cases with a high optical purity. (Figure presented.).
- Brenna, Elisabetta,Crotti, Michele,De Pieri, Matteo,Gatti, Francesco G.,Manenti, Gabriele,Monti, Daniela
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p. 3677 - 3686
(2018/06/04)
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- Preparation of o-Fluorophenols from Nonaromatic Precursors: Mechanistic Considerations for Adaptation to Fluorine-18 Radiolabeling
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The preparation of fluorine-18 labeled o-fluorophenols at high specific activity is challenging and requires use of [18F]fluoride ion as the radioisotope source. As a novel, alternative approach, we found that treatment of α-diazocyclohexenones with Selectfluor and Et3N·3HF followed by HF elimination and tautomerization afforded o-fluorophenols regioselectively and rapidly. To adapt this chemistry to 18F radiolabeling, using bromine electrophiles in place of Selectfluor gave the o-fluorophenol via an α-bromo-α-fluoroketone intermediate in lower but still reasonable yields.
- Yasui, Norio,Mayne, Christopher G.,Katzenellenbogen, John A.
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supporting information
p. 5540 - 5543
(2015/12/01)
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- Novel PDC catalyzed oxidative rearrangement of tertiary allylic alcohols to β-substituted enones
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Novel pyridinium dichromate (PDC) catalyzed oxidative rearrangement for the conversion of tertiary allylic alcohols to ?-substituted enones is described. Using a catalytic amount of PDC with PhI(OAc)2 as a co-oxidant in the presence of magnesium sulfate and water under oxygen was found effective for this rearrangement.
- Matsunaga, Kazuma,Hirajima, Hironori,Kishida, Atsushi,Takatori, Kazuhiko,Nagaoka, Hiroto
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p. 5941 - 5944
(2015/11/02)
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- Palladium-catalyzed oxidative rearrangement of tertiary allylic alcohols to enones with oxygen in aqueous solvent
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A one-pot procedure for Pd(TFA)2-catalyzed 1,3-isomerization of tertiary allylic alcohols to secondary allylic alcohols followed by a Pd(TFA)2/neocuproine-catalyzed oxidative reaction to β-disubstituted-α,β-unsaturated kenones was developed. (Chemical Equation Presented).
- Li, Jingjie,Tan, Ceheng,Gong, Jianxian,Yang, Zhen
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p. 5370 - 5373
(2015/01/09)
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- Oxidative conversion of silyl enol ethers to α,β-unsaturated ketones employing oxoammonium salts
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The oxidative conversion of silyl enol ethers to α,β-unsaturated ketones using a less-hindered class of oxoammonium salts (AZADO +BF4-) is described. The reaction proceeds via the ene-like addition of oxoammonium salts to silyl enol ethers.
- Hayashi, Masaki,Shibuya, Masatoshi,Iwabuchi, Yoshiharu
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supporting information; experimental part
p. 154 - 157
(2012/02/16)
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- Pt-catalyzed oxidative rearrangement of cyclic tertiary allylic alcohols to enones using aqueous hydrogen peroxide
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An oxidative rearrangement of cyclic tertiary allylic alcohols to β-disubstituted α,β-unsaturated ketones by Pt black catalyst with aqueous hydrogen peroxide is described. The reaction proceeds under organic solvent- and halide-free conditions and gives only water as a coproduct. The Pt black catalyst is commercially available and can be reused at least four times.
- Nagamine, Takashi,Kon, Yoshihiro,Sato, Kazuhiko
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p. 744 - 746
(2012/09/22)
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- Lewis acid-catalyzed oxidative rearrangement of tertiary allylic alcohols mediated by TEMPO
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Two methods for the oxidative rearrangement of tertiary allylic alcohols have been developed. Most of tertiary allylic alcohols studied were oxidized to their corresponding transposed carbonyl derivatives in excellent to fair yields by reaction with TEMPO in combination with PhIO and Bi(OTf)3 or copper (II) chloride in the presence or not of oxygen. Other primary oxidants of TEMPO such as PhI(OAc)2, mCPBA, and Oxone were unsatisfactory giving the enone in modest to low yields.
- Vatèle, Jean-Michel
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scheme or table
p. 904 - 912
(2010/03/24)
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- Copper-catalyzed aerobic oxidative rearrangement of tertiary allylic alcohols mediated by TEMPO
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A mild method for the oxidative rearrangement of tertiary allylic alcohols to β-substituted enones using a TEMPO/CuCl2 system, in the presence of molecular sieves, is described. Depending on the substrate, CuCl2 was used in either a catalytic amount under an oxygen atmosphere or stoichiometrically. Georg Thieme Verlag Stuttgart.
- Vatèle, Jean-Michel
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experimental part
p. 2143 - 2145
(2011/04/15)
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- IBS-catalyzed oxidative rearrangement of tertiary allylic alcohols to enones with oxone
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A 2-iodoxybenzenesulfonic acid (IBS)-catalyzed oxidative rearrangement of tertiary allylic alcohols to enones with powdered Oxone in the presence of potassium carbonate and tetrabutylammonium hydrogen sulfate has been developed.
- Uyanik, Muhammet,Fukatsu, Ryota,Ishihara, Kazuaki
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supporting information; experimental part
p. 3470 - 3473
(2009/12/05)
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- Regiodivergent 1,4 versus 1,6 asymmetric copper-catalyzed conjugate addition
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(Chemical Equation Presented) Metal matters: A highly regiodivergent copper-catalyzed asymmetric conjugate addition to α,β and γ,δ Michael acceptors is described. Zinc and aluminum reagents afford the 1,6 adduct with good to moderate enantioselectivity in the presence of ligand 1 (see scheme). In contrast, Grignard reagents used with hydroxy imidazolium ligand 2 afforded the 1,4 adduct with excellent ee values.
- Henon, Helene,Mauduit, Marc,Alexakis, Alexandre
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supporting information; scheme or table
p. 9122 - 9124
(2009/02/08)
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- Stereoselective aziridination of cyclic allylic alcohols using chloramine-T
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The stereoselective aziridination of a range of cyclic allylic alcohols using two different chloramine salts (4-MeC6H4SO 2NClNa, TsNClNa and t-BuSO2NClNa, BusNClNa) has been explored. The stereoselectivity of these reactions was highly dependent on the structure of the allylic alcohol and the chloramine salt. Generally, mixtures of cis- and trans-hydroxy aziridines were obtained, in which the major diastereomer was the cis-hydroxy aziridine, whilst complete cis- diastereoselectivity was observed in the aziridination of 1,3-disubstituted allylic alcohols. In each case studied, aziridination using BusNClNa gave higher cis-stereoselectivity than that observed for the same reaction using TsNClNa. Unexpectedly, application of the aziridination conditions to 1-substituted cyclopen-2-en-1-ols did not generate the aziridines. Instead, epoxy sulfonamides were obtained.
- Coote, Susannah C.,O'Brien, Peter,Whitwood, Adrian C.
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supporting information; experimental part
p. 4299 - 4314
(2009/02/07)
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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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- TEMPO/NaIO4-SiO2: A catalytic oxidative rearrangement of tertiary allylic alcohols to β-substituted α,β-unsaturated ketones
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(Chemical Equation Presented) The novel catalytic method for the oxidative rearrangement of tertiary allylic alcohols to β-substituted α,β-unsaturated ketones is described. TEMPO/NaIO4-SiO 2 causes facile and efficient oxidative rearrangement of various acyclic substrates as well as medium-sized and macrocyclic substrates.
- Shibuya, Masatoshi,Tomizawa, Masaki,Iwabuchi, Yoshiharu
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scheme or table
p. 4715 - 4718
(2009/05/31)
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- Oxidative rearrangement of tertiary allylic alcohols employing oxoammonium salts
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(Chemical Equation Presented) Practical and highly efficient methods for oxidative rearrangement of tertiary allylic alcohols to β-substituted α,β-unsaturated carbonyl compounds employing oxoammonium salts are described. The methods developed are applicable to acyclic substrates as well as medium membered ring substrates and macrocyclic substrates. The counteranion of the oxoammonium salt plays crucial roles on this oxidative rearrangement.
- Shibuya, Masatoshi,Tomizawa, Masaki,Iwabuchi, Yoshiharu
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p. 4750 - 4752
(2008/09/20)
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- Lewis acid promoted oxidative rearrangement of tertiary allylic alcohols with the PhIO/TEMPO system
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A mild and environmentally friendly method for Lewis acid catalyzed oxidative rearrangement of tertiary allylic alcohols to β-disubstituted enones by the TEMPO/PhIO system is described. Bismuth triflate was found to be the most efficient catalyst for the majority of the substrates tested except for tertiary vinyl carbinols which could be transformed to enals in fair yields only when Re2O7 was used as catalyst. A plausible mechanism for this oxidative rearrangement is discussed. Georg Thieme Verlag Stuttgart.
- Vatèle, Jean-Michel
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experimental part
p. 1785 - 1788
(2009/04/07)
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- Highly efficient methods for the one-pot synthesis of β-substituted enones
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A new mild and practically convenient one-pot procedure for the direct β-substitution of enones, developed using a conjugate addition-oxidation strategy with a full range of copper based reagents and N-tert- butylphenylsulfinimidoyl chloride, was analyzed. To start the investigation reaction of a simple Gilman cuprate, lithium di-n-butylcuprate, with cyclohex-2-enone was performed. The desired one-pot transformation was found to be achievable, albeit in a low 39% yield. The application of a series of individual organocuprate reagents was also investigated. It was observed that the technique provided good to excellent yields of β-substituted enones from all of the unsaturated starting materials employed.
- Kerr, William J.,Pearson, Colin M.,Thurston, Graeme J.
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- One-pot β-substitution of enones with alkyl groups to β-alkyl enones
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Vinylic hydrogens at the β-position of enones were effectively substituted with alkyl groups in a one-pot procedure to afford β-alkyl enones in good to high isolated yields by conjugate addition of higher-order dialkyl cyanocuprates to enones, followed by a reaction with N-tert-butylbenzenesulfinimidoyl chloride at -78 °C. The Royal Society of Chemistry 2005.
- Matsuo, Jun-Ichi,Aizawa, Yayoi
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p. 2399 - 2401
(2007/10/03)
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- Oxidative rearrangement of cyclic tertiary allylic alcohols with IBX in DMSO
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(Chemical Equation Presented) A practical and environmentally friendly method for oxidative rearrangement of five- and six-membered cyclic tertiary allylic alcohols to β-disubstituted α,β-unsaturated ketones by the IBX/DMSO reagent system is described. Several conventional protecting groups (e.g., Ac, MOM, and TBDPS) are compatible under the reaction conditions prescribed.
- Shibuya, Masatoshi,Ito, Shinichiro,Takahashi, Michiyasu,Iwabuchi, Yoshiharu
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p. 4303 - 4306
(2007/10/03)
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- An experimental and theoretical study of the type C enone rearrangement: Mechanistic and exploratory organic photochemistry
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We recently described a new photochemical rearrangement which we termed a Type C process. The reaction involves a δ to α aryl migration in 5-disubstituted cyclohexenones also having bulky C-3 substituents. In contrast to most cyclohexenone rearrangements, the reaction occurs via a twisted π-π* excited triplet rather than the usual n-π* state. The electronic nature of the rearrangement was assessed using migration selectivity with p-anisyl and p-cyanophenyl groups. A synthesis of the reactants was elaborated, and the product structures were established by X-ray and NMR analysis. The reaction mechanism was established further with DFT and CASSCF computations. In the latter, localized NBO basis orbitals permitted proper selection of the active space. The nature of the diradical intermediates as well as the transition states was established computationally. Sensitization experiments with regioselectivities the same as those in direct irradiation confirmed the triplet multiplicity of the process.
- Zimmerman, Howard E.,Nesterov, Evgueni E.
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p. 5422 - 5430
(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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- Oxidative rearrangement of bicyclo[n.1.0]alkan-1-ols in the presence of oxygen
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Peroxidated compounds were prepared by treatment of ether solutions of bicyclo[n.1.0]alkanols with oxygen in the presence of silica gel, ferric acetylacetonate and light.
- Morisson, Veronique,Barnier, Jean-Pierre,Blanco, Luis
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p. 4045 - 4046
(2007/10/03)
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- Chemo-enzymatic preparation of optically active endo- bicyclo[4.1.0]heptan-2-ols
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Resolutions of endo-bicyclo[4.1.O]heptan-2-ols were achieved by acylation in the presence of lipase from Candida antarctica (Novozym). The (1S,2R,6R) enantiomers reacted faster and the enantiomeric ratios were between 60 and 800 for the 6-substituted bicycloalkanols.
- Barnier, Jean-Pierre,Morisson, Veronique,Volle, Isabelle,Blanco, Luis
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p. 1107 - 1117
(2007/10/03)
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- Titanium(II)-based Z-reduction of alkynes. Syntheses of deuterium labelled linolenic and oleic acids and (3E,8Z,11Z)-tetradeca-3,8,11-trienyl acetate, the sex pheromone of a tomato pest, Scrobipalpuloides absoluta
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An operationally simple TiII-mediated, stereo- and regio-specific reduction of isolated, conjugated and methylene 'skipped' polyynes to the corresponding Z-polyenes in a one-pot procedure is described and applied inter alia to the syntheses of deuterium labelled linolenic and oleic acids. Final quenching with D2O (instead of H2O) results in regio- and stereo-specific Z-dideuteration of the alkyne. The synthesis of (3E,8Z,11Z)-tetradeca-3,8,11-trienyl acetate, the major sex pheromone of Scrobipalpuloides absoluta, a destructive pest of tomatoes, and the (3Z,8Z,11Z)-isomer, utilises this methodology in key reduction steps, and under- or over-reduction are negligible.
- Hungerford, Natasha L.,Kitching, William
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p. 1839 - 1858
(2007/10/03)
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- Carbonyl transposition on organoselenium compounds
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Carbonyl conjugated vinylic selenides undergo 1,3 and 1,5-carbonyl transposition sequences through organometallic reagents addition reactions followed by acid hydrolysis.
- Comasseto, Joao V.,Lo, Wai L.,Petragnani, Nicola
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p. 7445 - 7460
(2007/10/03)
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- Addition reactions of cyclic s-trans-enaminones with Grignard reagents
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Addition of Grignard reagents to s-transenaminones derived from 1,3-cycloalkanediones are described. In dichloromethane, addition of phenylmagnesium bromide gave 3-phenyl substituted cycloalkenones. Alkylmagnesium halides underwent multiple addition reactions, giving mixtures of the 3-alkylcycloalkenones and 1,3-dialkyl-3-(dialkylamino)cyclohexenes. In tetrahydrofuran, only the 3-alkylcycloalkenone was obtained.
- Shawe, Thomas T.,Hansen, Darren B.,Peet, Kelly Ann,Prokopowicz, Anthony S.,Robinson, Patrice M.,Cannon, Annatina,Dougherty, Kathleen E.,Ross, Andrew A.,Landino, Linda M.
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p. 1547 - 1556
(2007/10/03)
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- Two methods for the preparation of 2-cyclohexenones from resin-bound 1,3-cyclohexanedione
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The addition of organolithium or Grignard reagents to viny]ogous ester resin 1 followed by mild hydrolysis of product resins 2 provides 3-alkyl-2-cyclohexenones in high purity (>95%). Alternatively, conversion of 1 to vinyl triflate resin 4 followed by palladium-mediated couplings with aryl boronic acids and hydrolysis furnishes 3-ary]-2-cyclohexenones in lower yield, but exceptional purity.
- Fraley, Mark E.,Rubino, Robert S.
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p. 3365 - 3368
(2007/10/03)
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- Reaction of cyclic α-hydroxy epoxides with a strong base: A new 1,2-rearrangement, evidence for a carbenoid pathway
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Several substituted five- and six-membered cyclic α,β-unsaturated ketones are readily available by treatment of the corresponding α-hydroxy epoxides with an organolithium reagent. The reaction involves a new carbenoid 1,2-alkyl rearrangement. Evidence for the carbenoid intermediate has been obtained by an intramolecular trapping of the highly reactive species.
- Doris, Eric,Dechoux, Luc,Mioskowski, Charles
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p. 12700 - 12704
(2007/10/03)
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- Generation, Some Synthetic Uses, and 1,2-Vinyl Rearrangements of Secondary and Tertiary Homoallyllithiums, Including Ring Contractions and A Ring Expansion. Remarkable Acceleration of the Rearrangement by an Oxyanionic Group
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A very general preparative method for homoallyllithiums consists of reductive lithiation of homoallylithiums consists of reductive lithiation of homoallyl phenyl sulfides by lithium 4,4'-di-tert-butylbiphenylide.The sulfides can be prepared by a variety o
- Mudryk, Boguslaw,Cohen, Theodore
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p. 3855 - 3865
(2007/10/02)
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- Stereoselective radical cyclization of epoxy silyl enol ethers
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n-Bu3Sn radical catalyzed stereoselective radical cyclization of epoxy silyl enol ethers is described.
- Kim,Koh
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p. 7391 - 7392
(2007/10/02)
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- Application of Indium Ate Complexes to Synthetic Chemistry. Selective Conjugate Addition to Enones and Coupling with Allylic Halides
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Tetraorganoindium ate complexes, prepared by the addition of organolithium reagents to trialkylindium, reacted with α,β-unsaturated ketones in a 1,4-addition fashion; allylic indates derived from allylic indium sesquihalides coupled with allylic halides regio- and stereo-specifically to give high yields of hed-to-tail 1,5-dienes.
- Araki, Shuki,Shimizu, Toshio,Jin, Shun-Ji,Butsugan, Yasuo
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p. 824 - 825
(2007/10/02)
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- Reaction of organolithium reagents with η5-pentadienyl iron complexes: Formation of σ,η3-iron complexes
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Reaction of organolithium reagents with η5-pentadienyl iron complex 4 occurs at the C2/C4 position of the π-system, generating σ,η3-iron complexes 5. Air oxidation of these σ,η3-iron complexes generates cyclohexenones. Rea
- McDaniel, Keith F.,Kracker II, Larry R.,Thamburaj, Parinbam K.
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p. 2373 - 2376
(2007/10/02)
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- Synthesis of Carbocyclic Systems via Radical-Induced Epoxide Fragmentation
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Cis-fused bicyclic compounds are synthesized from simple monocyclic enone precursors.The key step involves a tandem radical-mediated epoxide fragmentation, radical translocation, and cyclization.
- Rawal, Viresh H.,Newton, Randall C.,Krishnamurthy, Venkat
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p. 5181 - 5183
(2007/10/02)
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- Organobis(cuprates): A New Class of Reagents and Method for Spiroannelation
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A one-step spiroannelation method applicable to the synthesis of the commonly encountered spirocyclic systems is described.The method involves the reaction of 3-halocycloalk-2-enones with a new type of cuprate reagent prepared from organodilithium reagents and copper thiophenoxide and is shown to provide efficient access to mspirononanes, spirodecanes, and spiroundecanes.The effects of temperature, concentration, and halogen variations on the efficiency of this process are reported for the reactions of 3-halo-5,5-dimethylcyclohex-2-enones 2a-c with 1,4-bis(CuSPhLi)butane (3).Under optimal conditions, chloroenone 2a reacts with reagent 3 to provide 9,9-dimethylspirodecan-7-one (5) in 96percent yield.The optimized conditions are found to apply generally to variously substituted halocyclopentenones and halocyclohexenones, providing the corresponding spirocyclic products in 76-93percent yield.The preparation of new dilithium reagents is also described along with their use in the spiroannelation procedure.The stability of the organobis(cuprates) is found to be influenced by the hybridization of the metal-bearing centers, with alkyl reagents more stable than alkenyl reagents.
- Wender, Paul A.,White, Alan W.
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p. 2218 - 2223
(2007/10/02)
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- SYNTHETIC APPLICATIONS OF 2-PHENYLSELENENYLENONES-III AN OVERVIEW
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2-Phenylselenenylenones are versatile species which can be selectively converted a number of different ketones and enones in high overall yields.
- Liotta, Dennis,Saindane, Manohar,Barnum, Christopher,Zima, George
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p. 4881 - 4890
(2007/10/02)
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- Carbon-Carbon Bond-Forming Reactions Using Cerium Metal or Organocerium(III) Reagents
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Carbon-carbon bond-forming reactions using cerium metal or organocerium(III) reagents have been investigated.Cerium amalgam is an effective reagent for the chemoselective preparation of homoallylic alcohols from allyl halides and carbonyl compounds.These same reagent can also be satisfactorily employed for the Reformatsky-type reaction of α-halo esters with carbonyl compounds.It has been shown that organocerium(III) reagents are conveniently generated by the reaction of organolithiums with cerium(III)iodide or cerium(III)chloride.The reagents are less basic thanorganolithiums or Grignard reagents, and they react cleanly at -78 to -65 deg C with various carbonyl compounds to afford the addition products in high yields, even though the substrates are susceptible to enolization or metal-halogen exchange with simple organolithiums.The same reagents react also with α,β-unsaturated compounds to yield 1,2-addition products in high selectivity.
- Imamoto, Tsuneo,Kusumoto, Tetsuo,Tawarayama, Yoshinori,Sugiura, Yasushi,Mita, Takeshi,et al.
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p. 3904 - 3912
(2007/10/02)
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- Reaction of β-halo α,β-unsaturated ketons with cuprate reagents. Efficient syntheses of β,β-dialkyl ketones and β-alkyl α,β-unsaturated ketones. A synthesis of (Z)-jasmone
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Treatment of the 3-halo-2-cyclohexen-1-ones 11-15 and 17 with an excess of lithium dimethylcuprate provided good to excellent yields of the corresponding 3,3-dimethylcyclohexanones 21-24.Similar reactions involving the β-bromo cyclopentenones 19 and 20 stopped at the monoaddition stage, producing the cyclopentenones 40 and 43.Reaction of the β-bromo cyclohexenones 12 and 15 with 1.1 equiv. of lithium dimethylcuprate did not effect clean conversion of these substrates into the corresponding 3-methyl-2-cyclohexen-1-ones.When a series of β-bromo enones 12, 14-19were allowed to react with the lithium (phenylthio)(alkyl)cuprates 44-47, the correspondig β-alkyl enones were, in general, produced cleanly and efficiently.However, reaction of 3-bromo-2-methyl-2-cyclopenten-1-one (19) with the cuprate reagent 44 gave mainly the β-phenylthio enone 49.This undesired result could be avoided by employing, in the place of 19, The β-iodo cyclopentenone 50, which reacted smoothly with 44 to give a high yield of 2,3-dimethyl-2-cyclopenten-1-one (40).Reaction of 3-bromo-2-cyclohexen-1-one (14) with 3 equiv. of the mixed vinylcuprate reagent 48 gave 3-(3-butenyl)-2-cyclohexen-1-one (32).Alkylation of 1,3-cyclopentanedione with (Z)-1-chloro-2-pentene afforded compound 51, which was converted into the β-bromo enone 52.Treatment of the latter substance with lithium dimethylcuprate provided (Z)-jasmone (53).
- Piers, Edward,Cheng, Kin Fai,Nagakura, Isao
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p. 1256 - 1263
(2007/10/02)
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- A SIMPLE SYNTHESIS OF α,β-UNSATURATED CARBONYL COMPOUNDS BY TRAPPING THE MICHAEL ADDITION-ENOLATE ANION WITH METHANESULFINYL CHLORIDE
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Trapping of an enolate anion, formed by the Michael addition, with methanesulfinyl chloride and subsequent desulfinylation is found to be a useful method for the synthesis of various α,β-unsaturated carbonyl compounds.Synthetic utility of this method is demonstrated in the synthesis of geraniol, nerol, farnesol, and dihydrojasmone.
- Fujisawa, Tamotsu,Noda, Atsunari,Kawara, Tatsuo,Sato, Toshio
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p. 1159 - 1160
(2007/10/02)
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