- A simple and highly efficient procedure for construction of quaternary carbons centers by tributylphosphine catalyzed bis-Michael addition
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The tributylphosphine-catalyzed bis-Michael addition reaction of various kinds of α,β-unsaturated carbonyl compounds with active methylenes is described. This is a convenient and rapid method for generating quaternary carbons centers and useful procedure for the synthesis of branched core and highly substituted trans cyclohexanones. All the reactions were completed in 60 min and afford the corresponding products in excellent yields.
- Xu, Da-Zhen,Zhan, Ming-Zhe,Huang, You
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- A simple, efficient and green procedure for Michael addition catalyzed by [C4dabco]OH ionic liquid
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A dabco-based basic ionic liquid, 1-butyl-4-aza-1-azaniabicyclo[2.2.2] octane hydroxide, has been developed as a catalyst for a convenient and rapid method for the Michael addition of active methylene compounds to α,β-unsaturated carboxylic esters and nitriles. The method is very simple, and the yields are very high. The catalyst can be recycled several times without much loss of activity.
- Keithellakpam, Sanjoy,Laitonjam, Warjeet S.
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p. 767 - 770
(2014/06/09)
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- 1,8-Diazabicyclo[5.4.0]undec-7-ene (DBU): A powerful catalyst for the Michael addition reaction of β-ketoesters to acrylates and enones
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The Michael addition reaction of 1,3-dicarbonyl compounds and enones was carried out in the presence of a catalytic amount of 1,8-diazabicyclo[5.4.0]undec-7-ene (DBU) in ethanol under the mild reaction condition furnished Michael adducts in excellent yield.
- Muthusamy, Sengodagounder,Babu, Srinivasarao Arulananda,Gunanathan, Chidambaram
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p. 3247 - 3254
(2007/10/03)
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- Binary caesium-lanthanum oxide supported on MCM-41: A new stable heterogeneous basic catalyst
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Heterogeneous mesoporous stable basic catalysts have been prepared by wet or solid-state impregnation of MCM-41 with caesium acetate and lanthanum nitrate followed by thermal decomposition. 133Cs MAS NMR data of CsLa/MCM-41 show an increase in
- Kloetstra,Van Laren,Van Bekkum
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p. 1211 - 1220
(2007/10/03)
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- Ruthenium-catalyzed aldol and Michael reactions of nitriles. Carbon-carbon bond formation by α-C-H activation of nitriles
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The ruthenium(II)-catalyzed reaction of nitriles with carbonyl compounds proceeds highly efficiently under neutral and mild conditions to give α,β-unsaturated nitriles. Under similar reaction conditions, nitriles react with olefins bearing electron-withdrawing groups to give the corresponding Michael adducts. The efficiency of the reaction is illustrated by the selective additions to α,β-unsaturated aldehydes and acetylenes bearing electron-withdrawing groups, which are difficult to perform using conventional bases. Chemoselective aldol and Michael reactions of nitriles can be performed in the presence of other active methylene compounds. Tandem Michael and Michael-aldol condensations of nitriles 30 can be performed with high diastereoselectivity. These reactions can be rationalized by assuming oxidative addition of ruthenium(0) to the α-C-H bond of nitriles and subsequent insertions to carbonyl compounds or olefins. As the key intermediates and active catalysts hydrido(N-bonded enolato)ruthenium(II) complexes, mer-RuH(NCCHCO2R)(NCCH2CO2R)(PPh3)3 (R = Me (41a), Et (41b), n-Bu (41c)) have been isolated upon treatment of RuH2(PPh3)4 (3) or RuH(C2H4)(PPh3)2(PPh2C6H4) (4) with alkyl cyanoacetates. Kinetic study of the catalytic aldol reaction of ethyl cyanoacetate with benzaldehyde indicates that the rate-determining step is the reaction of enolato complex 41 with aldehydes.
- Murahashi, Shun-Ichi,Naota, Takeshi,Taki, Hiroshi,Mizuno, Masahiko,Takaya, Hikaru,Komiya, Sanshiro,Mizuho, Yuji,Oyasato, Naohiko,Hiraoka, Makiko,Hirano, Masafumi,Fukuoka, Atsushi
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p. 12436 - 12451
(2007/10/03)
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- SYNTHESIS OF POLYFUNCTIONAL ALIPHATIC CARBONYL COMPOUNDS UNDER PHASE-TRANSFER CONDITIONS
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We have studied mono- and dialkylation of malonic, acetoacetic, and cyanoacetic esters with esters of haloacetic and β-halopropionic acids and addition of the CH acids mentioned and their analogues to methyl and ethyl acrylate under phase-transfer catalysis conditions, and also deethoxycarbonylation of the obtained products.We have demonstrated for the first time the possibility of Dieckmann cyclization under phase-transfer catalysis conditions and have developed a simple method for the synthesis of 2,3-di(ethoxycarbonyl)cyclopentanone, a key intermediate in the synthesis of deoxyprostaglandins, by cyclization of triethyl 1,2,4-butanetricarboxylate.
- Sizov, A. Yu.,Dombrovskii, V. A.,Yanovskaya, L. A.
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p. 955 - 961
(2007/10/02)
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