- Convenient synthesis of a reactive ester homoenolate
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Reaction between methyl 3-phenyl-3-trimethylsilylpropionate (8) and catalytic quantities of tetrabutylammonium triphenyldifluorosilicate (TBAT) effects desilylation to the corresponding homoenolate, which can be trapped by a variety of electrophiles. Rear
- DiMauro, Erin,Fry, Albert J.
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Read Online
- Fluoride-promoted reactions of unsaturated carbonyl compounds. Dimerization by a non-Baylis-Hillman pathway
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Fluoride ion acts as a base toward α,β-unsaturated esters and cyclohexenone to induce self-condensation and/or double-bond isomerization.
- Xuan, Judy X.,Fry, Albert J.
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Read Online
- Template Catalysis by Metal-Ligand Cooperation. C-C Bond Formation via Conjugate Addition of Non-activated Nitriles under Mild, Base-free Conditions Catalyzed by a Manganese Pincer Complex
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The first example of a catalytic Michael addition reaction of non-activated aliphatic nitriles to α,β-unsaturated carbonyl compounds under mild, neutral conditions is reported. A new de-aromatized pyridine-based PNP pincer complex of the Earth-abundant, first-row transition metal manganese serves as the catalyst. The reaction tolerates a variety of nitriles and Michael acceptors with different steric features and acceptor strengths. Mechanistic investigations including temperature-dependent NMR spectroscopy and DFT calculations reveal that the cooperative activation of alkyl nitriles, which leads to the generation of metalated nitrile nucleophile species (α-cyano carbanion analogues), is a key step of the mechanism. The metal center is not directly involved in the catalytic bond formation but rather serves, cooperatively with the ligand, as a template for the substrate activation. This approach of "template catalysis" expands the scope of potential donors for conjugate addition reactions.
- Nerush, Alexander,Vogt, Matthias,Gellrich, Urs,Leitus, Gregory,Ben-David, Yehoshoa,Milstein, David
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p. 6985 - 6997
(2016/07/06)
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- Hydroxy chalcogenide-promoted Morita-Baylis-Hillman Alkylation reaction: Intermolecular applications with alkyl halides as electrophiles
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Hydroxysulfides acted as catalysts to promote the Morita-Baylis-Hillman alkylation reaction of cyclohexenones and dihydropyridinones. The procedure worked efficiently with a variety of halides as electrophiles. Side reactions were in competition with the MBH alkylation, but fine-tuning the reaction conditions minimized their occurence.
- Gradillas, Ana,Belmonte, Efres,Da Silva, Rondes Ferreira,Perez-Castells, Javier
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p. 1935 - 1941
(2014/04/03)
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- Hydroxy Chalcogenide-Promoted Morita-Baylis-Hillman Alkylation Reaction: Intermolecular Applications with Alkyl Halides as Electrophiles
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Hydroxysulfides acted as catalysts to promote the Morita-Baylis-Hillman alkylation reaction of cyclohexenones and dihydropyridinones. The procedure worked efficiently with a variety of halides as electrophiles. Side reactions were in competition with the
- Gradillas, Ana,Belmonte, Efres,Da Silva, Rondes Ferreira,Prez-Castells, Javier
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p. 1935 - 1941
(2015/10/05)
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- Multicomponent asymmetric reactions mediated by proline lithium salt
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The multicomponent reaction between proline lithium salt, 2-cyclohexen-1-one and aliphatic aldehydes affords the 4-alkylidene-2- cyclohexen-1-ones, which are interesting fragrances, and bicyclic amino acids that bear four additional stereocenters, obtaine
- Renzi, Polyssena,Overgaard, Jacob,Bella, Marco
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supporting information; experimental part
p. 980 - 983
(2010/06/13)
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- A novel method for the high-pressure-promoted, uncatalyzed aza-Michael reaction of nitrogen heterocycles with enones in water
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A new green chemical method for the aza-Michael reaction of nitrogen heterocycles with enones in water as a solvent without the use of any catalysts under high-pressure conditions is described. Georg Thieme Verlag Stuttgart.
- Uddin, Md. Imam,Nakano, Keiji,Ichikawa, Yoshiyasu,Kotsuki, Hiyoshizo
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experimental part
p. 1402 - 1406
(2009/04/06)
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- Superoxide Anion Radical (O2)-radical Mediated Base-Catalyzed Autoxidation of Enones
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Seventeen variously substituted cyclohex-2-en-1-ones were prepared and reacted with superoxide anion radical (O2-radical generated from KO2/18-crown-6) in inert nonpolar aprotic media at room temperature.The 4,4,6,6-tetrasubstituted cyclohexenones (1b,1c, and 1d) proved to be totally inert,while those cyclohexenones possessing available acidic α'- or γ-hydrogens underwent O2-radical mediated base-catalysed autoxidation (BCA) generating various products depending on the nature and location of the substituents.Thus, 4,4- and 5,5-disubstituted substrates(2b, 2c, 2e, 2f and 3b, 3d, 3f-3i, respectively) gave 2-hydroxycyclohexa-2,5-dien-1-ones (7) as the major product (>80percent yield) upon aqueous acid workup while the corresponding 2-methoxy analogues 8 are obtained when the reaction is quenched with CH3I. 2,3-Epoxycyclohexanones 13 and oxidative cleavage products 11 and 12 are formed in the case of the 6,6-disubstituted systems (4a-4c); these oxidation products are accompanied by dimers 14 when the substituent on 4 is CH3 or H.Epoxide 23 is the primary isolable product in the 3,4,4-trialkyl system (5d).As expected for BCA processes, similar results were observed when these reactions were mediated by KOH (at room temperature) or KOC(CH3)3 (at -40 deg C).In the case of 6,6-diphenylcyclohex-2-en-1-one (4c), however, tert-butoxide-mediated BCA at -40 deg C yielded cyclopentene hydroxy acid 15 in addition to epoxide 13.The saturated analogue of 4c, 18, yielded primarily the corresponding saturated hydroxy acid 19, as well as several other oxidation products (20-22) depending on the reaction conditions.The mechanism of these transformations is rationalized in terms of base-induced reactions and rearrangements of the initially formed keto hydroperoxides.
- Frimer, Aryeh A.,Gilinsky-Sharon, Pessia,Aljadeff, Gladis,Gottlieb, Hugo E.,Hameiri-Buch, Judith,et al.
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p. 4853 - 4866
(2007/10/02)
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- OXIDATION OF THE α-KETOL AND ENONE DERIVATIVES OF CYCLOHEXANONE BY TETRAZOLIUM SALTS
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A new red-ox reaction, leading to the respective keto derivatives from α-ketol and enone derivatives of cyclohexanone, is reported.
- Jasiczak, Jan
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p. 4323 - 4326
(2007/10/02)
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