- Cage Like Al-KIT-5 Mesoporous Materials for C-C Bond Formation Reactions under Solvent Free Conditions
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The C-C bond forming reactions are of fundamental importance in chemistry. As a result there is ever growing interest for chemists to develop new methods for C-C bond formation. We report here three dimensional nano-cage mesoporous aluminosilicate materia
- Baruah, Pranjal K.,Dutta, Prantu,Kalita, Pranjal
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- The Mukaiyama-Michael addition of a β,β-dimethyl substituted silyl ketene acetal to α,β-unsaturated ketones using tetra-n-butylammonium bibenzoate as a nucleophilic catalyst
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The Michael addition of a β,β-dimethyl substituted silyl ketene acetal [Me2C=C(OMe)OSiMe3] to α,β-unsaturated ketones, namely, 2-cyclopentenone, 2-cyclohexenone, 3-methyl-2-cyclohexenone, isophorone, methyl vinyl ketone and mesityl o
- Gnaneshwar, Rudhramyna,Wadgaonkar, Prakash P.,Sivaram, Swaminathan
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- BR?NSTED-ACIDIC FLUOROALKYL PHOSPHONATES
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The invention relates to Br?nsted-acidic fluoroalkyl phosphonates as bifunctional catalysts and to processes for the preparation thereof.
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Paragraph 0215-0219; 0220
(2018/10/04)
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- Pentafluorophenylammonium trifluoromethanesulfonimide: Mild, powerful, and robust catalyst for mukaiyama aldol and mannich reactions between ketene silyl acetals and ketones or oxime ethers
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Pentafluorophenylammonium trifluoromethanesulfonimide (C6F 5N+H3·NTf2-) promotes Mukaiyama aldol and Mannich reactions using ketene silyl acetals with ketones and oxime ethers, respectively. The prese
- Nagase, Ryohei,Osada, Jun,Tamagaki, Hiroaki,Tanabe, Yoo
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experimental part
p. 1128 - 1134
(2010/06/20)
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- Organotin perfluorooctanesulfonates as air-stable Lewis acid catalysts: Synthesis, characterization, and catalysis
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The reactions of 1,3-dichloro-1,1,3,3-tetrabutyldistannoxane and di-alkyltin dihalides with silver perfluoro-octanesulfonate provided the corresponding sulfonates as hydrates. The number of water molecules (n) of hydration was dependent on the conditions. The distannoxane derivative was identified as n from 0.5 to 6, while in the hydrated mononuclear species and DMSO complexes n varied widely from 4 to 13. 119Sn NMR spectroscopy and conductivity measurements indicated the ionic dissociation of these compounds in solution. These compounds exhibited unusually high solubility in polar organic solvents. The ionic dissociation together with facile hydration probably causes the unusual solubility. The Lewis acidity of these compounds was found to be high among organotin derivatives on the basis of ESR spectra of Superoxide/ metal-ion complexes. In contrast to well-known organotin Inflates, these compounds suffered no hydrolysis upon storage in open air. The high catalytic activity of the distannoxane 1 was exemplified for various carboncarbon bond-forming reactions, such as Mukaiyama-aldol as well as -Michael reactions and allylation of aldehydes.
- An, De Lie,Peng, Zhihong,Orita, Akihiro,Kurita, Akinobu,Man-E, Sumiyo,Ohkubo, Kei,Li, Xingshu,Fukuzumi, Shunichi,Otera, Junzo
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p. 1642 - 1647
(2007/10/03)
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- An environmentally friendly procedure for Mukaiyama aldol and Mukaiyama-Michael reactions using a catalytic amount of DBU under solvent- and metal-free conditions
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Mukaiyama aldol and Mukaiyama-Michael reactions can proceed smoothly in the presence of a catalytic amount of DBU (20% mmol), to afford the corresponding products in moderate to good yields. This solvent- and metal-free approach provides an environmentall
- Shen, Zhi-Liang,Ji, Shun-Jun,Loh, Teck-Peng
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p. 507 - 508
(2007/10/03)
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- Lewis base-catalyzed Michael reactions between trimethylsilyl enolate and α,β-unsaturated carbonyl compounds
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Michael reactions between trimethylsilyl enolates and α,β- unsaturated carbonyl compounds by using a Lewis base catalyst such as lithium benzamide 4 or lithium succinimide 5 in DMF proceeded smoothly to afford the corresponding Michael-adducts in good to high yields (Tables 1-3). In order to extend the scope, Michael reactions catalyzed by lithium acetate (AcOLi), a weak and readily available Lewis base, were studied in detail. AcOLi behaved as an effective Lewis base catalyst in Michael reactions between trimethylsilyl enolates and α,β-unsaturated carbonyl compounds at 0 °C or at room temperature (Tables 4-6). Hindered α,β-unsaturated ketones behaved as excellent Michael-acceptors in the above reaction at room temperature (Table 5). This catalytic Michael reaction also proceeds smoothly in the presence of other lithium carboxylates that are easily prepared in situ by treating carboxylic acids with lithium carbonate (LE2CO3) (Scheme 2). This is the first example of Lewis base-catalyzed Michael reactions between α,β-unsaturated carbonyl compounds and trimethylsilyl enolates.
- Nakagawa, Takashi,Fujisawa, Hidehiko,Nagata, Yuzo,Mukaiyama, Teruaki
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p. 236 - 246
(2008/02/04)
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- Lewis base catalyzed Michael reaction between ketene silyl acetals and α,β-unsaturated carbonyl compounds
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Catalytic Michael reaction between trimethylsilyl enolates and α,β-unsaturated carbonyl compounds by using a Lewis base such as lithium benzamide or lithium succimide in a DMF solvent proceeded smoothly to afford the corresponding Michael adducts.
- Mukaiyama, Teruaki,Nakagawa, Takashi,Fujisawa, Hidehiko
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- Tandem Mukaiyama Michael-aldol reactions catalysed by samarium diiodide
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Samarium diiodide is an efficient precatalyst for tandem Michael-aldol reactions, which allow the formation of two carbon-carbon bonds by successive additions of a ketene silyl acetal and an aldehyde on cyclic α,β-unsaturated ketones. The adducts are isolated as silyl ethers, in good yields, and in some cases with high diastereoselectivities when the reactions are performed at low temperatures. Comparative study of the activities of other lanthanide iodides for the same tandem reactions is presented. A key step for a formal synthesis of PGF2α has been performed by a tandem Michael-aldol samarium-catalysed sequence.
- Giuseppone, Nicolas,Collin, Jacqueline
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p. 8989 - 8998
(2007/10/03)
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- Spontaneous aldol and Michael additions of simple enoxytrimethylsilanes in DMSO
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Activation of simple trimethylsilyl ketene acetals by dipolar aprotic solvents has been evidenced, allowing efficient solvent assisted aldol and Michael additions under extremely simple, mild and metal free conditions. (C) 2000 Elsevier Science Ltd.
- Génisson, Yves,Gorrichon, Liliane
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p. 4881 - 4884
(2007/10/03)
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- Indium-trichloride catalyzed Michael reaction of silyl enol ethers with α,β-unsaturated carbonyl compounds under neat condition
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In the presence of a catalytic amount of indium (III) trichloride (InCl3) (20 mol%), ketene silyl enol ethers react quickly with α, β- unsaturated ketones and esters to afford the corresponding Michael adducts in moderate to good yields. Indium(III) trichloride can be recovered and reused without decrease in yields.
- Loh, Teck-Peng,Wei, Lin-Li
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p. 7615 - 7624
(2007/10/03)
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- Tris(pentafluorophenyl)boron as an Efficient, Air Stable, and Water Tolerant Lewis Acid Catalyst
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Tris(pentafluorophenyl)boron is an efficient, air stable, and water tolerant Lewis acid catalyst for the aldol-type and Michael reactions of silyl enol ethers with carbonyl compounds or other electrophiles (trimethyl orthoformate, dimethal acetal, and chloromethyl methyl ether), the allylation reaction of allylsilanes with aldehydes, and the Diels-Alder reaction of dienes with α,β-unsaturated-aldehydes.A solution of formaldehyde in water is applicable as an electrophile.Also, the aldol-type reaction of ketene silyl acetals with aromatic or aliphatic imines is successfully carried out using the same catalyst.
- Ishihara, Kazuaki,Hanaki, Naoyuki,Funahashi, Miyuki,Miyata, Mayumi,Yamamoto, Hisashi
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p. 1721 - 1730
(2007/10/02)
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- Lanthanide trifluoromethanesulfonates as reusable catalysts. Michael and Diels-Alder reactions
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The Michael reaction of silyl enolates with α,β-unsaturated ketones and the Diels-Alder reaction of carbonyl containing dienophiles are catalyzed by a catalytic amount of lanthanide trifluoromethanesulfonate to give the corresponding adducts in high yields. In both reactions, the catalyst can be recovered and reused.
- Kobayashi,Hachiya,Takahori,Araki,Ishitani
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p. 6815 - 6818
(2007/10/02)
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- Addition of Ketene Trimethylsilyl Acetals to α,β-Unsaturated Ketones: A New Strategy for Michael Addition of Ester Enolates
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Trialkylsilyl ketene acetals in the presence of tris(dimethylamino)sulfonium difluorotrimethylsiliconate generate very potent carbon nucleophiles formally equivalent to ester enolates.In sharp contrast to the commonly used lithium enolates, these acetals
- RajanBabu, T. V.
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p. 2083 - 2089
(2007/10/02)
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