- The discovery of a novel route to highly substituted -tropolones enables expedient entry to the core of the gukulenins
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A simple and general method for the synthesis of highly substituted α-tropolone ethers that allows rapid access to the bis(tropolone) core of the antiproliferative metabolites (-)-gukulenins A and F (3, 4) is described. The reaction proceeds by thermolyti
- Kats-Kagan, Roman,Herzon, Seth B.
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- Conjugate reduction of α,β-unsaturated carbonyl compounds catalyzed by a copper carbene complex
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(Matrix presented) An N-heterocyclic carbene copper chloride (NHC-CuCl) complex (2) has been prepared and used to catalyze the conjugate reduction of α,β-unsaturated carbonyl compounds. The combination of catalytic amounts of 2 and NaOt-Bu with poly(methy
- Jurkauskas, Valdas,Sadighi, Joseph P.,Buchwald, Stephen L.
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p. 2417 - 2420
(2007/10/03)
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- Dynamic kinetic resolution via asymmetric conjugate reduction: Enantio- and diastereoselective synthesis of 2,4-dialkyl cyclopentanones
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Herein, we report the kinetic and the dynamic kinetic resolutions of racemic 3,5-dialkyl-2-cyclopenten-1-ones. Kinetic resolution, with good selectivity factors (25-52), was achieved by conjugate reduction with catalytic CuCl/NaOt-Bu/(S)-p-tol-BINAP and s
- Jurkauskas, Valdas,Buchwald, Stephen L.
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p. 2892 - 2893
(2007/10/03)
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- A short and efficient synthesis of (±)-trans-sabinene hydrate
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A short synthesis of sabinene hydrate is reported. It uses cheap starting materials and affordable reagents. The main product of the synthesis is trans-sabinene hydrate.
- Galopin, Christophe C.
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p. 5589 - 5591
(2007/10/03)
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- An efficient synthesis of 2-cyclopentenones from γ-ketoaldehyde acetals using lithium trimethylsilyldiazomethane. Its application to the synthesis of trichodenone C
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The reaction of γ-ketoaldehyde acetals with lithium trimethylsilyldiazomethane afforded 2-cyclopentenones via the 1,5-C-H insertion of alkylidene carbene in high to moderate yields. Using this method, the synthesis of trichodenone C was achieved. (C) 2000 Elsevier Science Ltd.
- Sakai,Aoyama,Shioiri
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p. 6859 - 6863
(2007/10/03)
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- A General Preparative Method for Carbonyl-Protected γ-Lithioketones via Reductive Lithiation. Synthetic Uses of the Bishomoenolate Equivalents
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The mixed cuprates, generated by reductive lithiation of bis(phenylthio)acetals using lithium 4,4'-di-tert-butylbiphenylide (LDBB), followed by addition of cuprous bromide-dimethyl sulfide complex, undergo conjugate addition to enones in the presence of t
- Cohen, Theodore,Zhang, Birong,Cherkauskas, John P.
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p. 11569 - 11584
(2007/10/02)
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- Pressure-Induced Diastereoselectivity in Photochemical Cycloaddition Reactions
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Photochemical cycloaddition reactions under high pressure of cyclopentenone 1a or cyclohexenone 15, as well as of 1a or 3-substituted cyclopentenones 1b-d with cyclopentene (2), and of 1b with 3,3-dimethyl-1-butene (18) are described.Whereas the pressure dependence on the regioselectivity in the photoaddition of 1a and 15 is very small, ΔΔV* values up to 2.0 +/- 0.3 cm3 mol-1 have been found for the diastereoselectivity in the reactions of 1a-d with 2 and of 1b with 18. Key Words: High-pressure reactions / Photocycloaddition reactions / Diastereoselectivity / Cyclopentenones / Cyclopentenes
- Buback, Michael,Buenger, Joachim,Titze, Lutz F.
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p. 2577 - 2582
(2007/10/02)
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- 91. Photorearrangement of 4,4-Dimethylcyclohex-2-enones with Alkyl or Fluoro Substituents at C(5) and C(6): in Search of the Mechanism
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The photorearrangement of cyclohex-2-enones 4a-h to bicyclohexan-2-ones 5 and cyclopent-2-enones 6 (λ = 350 nm, MeCN) was investigated.Both the quantum yield (Φ-4 = 0.004 - 0.024) and the product ratio (5/6 = 65:35 - 31:69) vary only over a rather small range, indicating the rearrangement to be relatively insensitive to substituents on C(5) or C(6).Compounds 4b, 4c, and 4g with just one alkyl group at either C(6) or C(5) rearrange selectively to the diastereoisomer 5 with alkyl group and three-membered ring in trans-configuration, while 6-fluorocyclohex-2-enones 4d and 4f afford mixtures of diastereoisomeric bicyclohexanones.Mechanistic conclusions regarding an intermediate trimethylene biradical are presented.
- Cruciani, Giuliano,Margaretha, Paul
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p. 890 - 895
(2007/10/02)
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- Photochemistry of 6-trifluoromethyl-4,4-dimethyl-2-cyclohexenone
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The photochemical behaviour of the title compound, newly synthesized in four steps from 4,4-dimethylcyclohexanone, is compared to that of 4,4-dimethyl- and 4,4,6-trimethyl-2-cyclohexenone. All three enones undergo rearrangement to bicyclo[3.1.0]hexan-2-on
- Cruciani,Margaretha
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