- 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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Read Online
- C-H Bond Activation by Ruthenium(0) Complexes. Isolation of an Active Intermediate in the Ruthenium Catalyzed Aldol and Michael Reactions
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Carbon-hydrogen bond oxidative addition of alkyl cyanoacetate to Ru(C2H4)(PPh3)3 in benzene at room temperature gives mer-RuH(NCCHCOOR)(NCCH2COOR)(PPh3)3 (R=Me, Et) accompanied by the liberation of ethylene.X-Ray structure analysis of the THF adduct (R=Me) reveals that NCCHCOOMe group bonds to ruthenium not through the methine carbon but the cyano group.These complexes react with benzaldehyde and methyl iodide to give alkyl (E)-1-cyanocinnamate and alkyl-2-cyanopropionate, respectively.
- Mizuho, Yuji,Kasuga, Noriko,Komiya, Sanshiro
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Read Online
- Trimaleimide Linkers and Uses Thereof
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A type of trimaleimide linkers and uses thereof are disclosed. The trimaleimide linkers can be applied for preparation of antibody-drug conjugate as shown by formula I: L– (T–A–D) n Ⅰ wherein, L is an antibody, antibody fragment or protein; T is a trimaleimide linker; A is a cleavable linker group or a noncleavable linker; D is a drug; n is an integer ranging from 1 to 8.
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Page/Page column 35
(2016/12/22)
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- The remarkable catalytic activity of ultra-small free-CeO2 nanoparticles in selective carbon-carbon bond formation reactions in water at room temperature
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A simple and efficient protocol for selective bis-Michael addition and mono-allylation of active methylene compounds has been demonstrated using ultra-small (size ~5 nm) uncapped cerium oxide nanoparticles (free-CeO2 NPs) as a reusable catalyst in water at room temperature. The free-CeO2 NPs were characterized by powder XRD, TEM and XPS studies. Free-CeO2 NPs efficiently catalyzed both the reactions and produced good to excellent yields of products.
- Banerjee, Subhash
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supporting information
p. 5350 - 5353
(2015/07/07)
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- Remarkable catalytic activity of silica nanoparticle in the bis-Michael addition of active methylene compounds to conjugated alkenes
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We have demonstrated the remarkable catalytic activity of silica nanoparticles (NPs) in the unusual bis-Michael addition of active methylene compounds to conjugated alkenes at room temperature. The catalyst silica NPs were reused up to seven runs without appreciable loss of catalytic activity.
- Banerjee, Subhash,Santra, Swadeshmukul
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experimental part
p. 2037 - 2040
(2009/09/05)
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- Ionic liquid as catalyst and solvent: the remarkable effect of a basic ionic liquid, [bmIm]OH on Michael addition and alkylation of active methylene compounds
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A basic ionic liquid, 1-methyl-3-butylimidazolium hydroxide, [bmIm]OH, catalyzes the Michael addition of active methylene compounds to conjugated ketones, carboxylic esters and nitriles. It further catalyzes the addition of thiols to α,β-acetylenic ketones and alkylation of 1,3-dicarbonyl and -dicyano compounds. The Michael addition to α,β-unsaturated ketones proceeds in the usual way, giving the monoaddition products, whereas addition to α,β-unsaturated esters and nitriles leads exclusively to the bis-addition products. The α,β-acetylenic ketones undergo double conjugate addition with thiols producing β-keto 1,3-dithio-derivatives. In the alkylation reaction the acyclic 1,3-diketones are monoalkylated, whereas cyclic ketones undergo dialkylation under identical conditions. All these reactions were carried out without any organic solvent. The ionic liquid can also be recycled.
- Ranu, Brindaban C.,Banerjee, Subhash,Jana, Ranjan
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p. 776 - 782
(2007/10/03)
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- Ionic liquid as catalyst and reaction medium. The dramatic influence of a task-specific ionic liquid, [bmIm]OH, in Michael addition of active methylene compounds to conjugated ketones, carboxylic esters, and nitriles
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(Chemical Equation Presented) A task-specific ionic liquid, [bmIm]OH, has been introduced as a catalyst and as a reaction medium in Michael addition. Very interestingly, although the addition to α,β-unsaturated ketones proceeds in the usual way, giving the monoaddition products, this ionic liquid always drives the reaction of open-chain 1,3-dicarbonyl compounds with α,β-unsaturated esters and nitriles toward bis-addition to produce exclusively bis-adducts in one stroke.
- Ranu, Brindaban C.,Banerjee, Subhash
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p. 3049 - 3052
(2007/10/03)
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- Polynuclear branched tetrazole systems. 2*. New 2-(5-tetrazolyl) ethyl podands and their NH-acidity
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Nine new polynuclear 2-(5-tetrazolyl)ethyl podands have been obtained by the azidation of the corresponding nitriles. Using Bjerrum distribution functions, the values of pKa1, pKa 2, pKa3, and pKa4 have been determined by a potentiometric method for 14 polynuclear tetrazoles in aqueous and aqueous methanolic solution. The found values lie in the range from 3.5 to 7.5 pH units. The overall rules and the sequence of the ionization of the spatially separated tetrazole fragments in these podand systems are discussed.
- Zubarev,Bezklubnaya,Pyartman,Trifonov,Ostrovskii
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p. 1317 - 1325
(2007/10/03)
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- Synthesis of N-bonded enolatoruthenium(II) by oxidative addition of alkyl cyanocarboxylate to a ruthenium(0) complex
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Reaction of a zero-valent ruthenium complex [Ru(cot)(cod)] 1 (cod = 1,5-cyclooctadiene; cot = 1,3,5-cyclooctatriene) with alkyl cyanoacetate in the presence of mono- and bi-dentate tertiary phosphines gave a series of hydrido(enolato)-ruthenium(n) complexes: mer-[RuH(NCCHCO2Et)(NCCH2CO2Et)(PPh 3)3] 2; trans-[RuH(NCCHCO2Et)(cod)-(dppe)] 3 (dppe = Ph2PCH2CH2PPh2); trans-[RuH(NCCR1CO2R2)(dppe)2] (R1 = H, R2 = Et 4a: or Pri 4b; R1 = Me, R2 = Et 4c) and trans-[RuH(NCCMeCO2Et)(PMePh2)4] 5. The molecular structure of 3 shows that the enolato ligand co-ordinates to the ruthenium centre via the cyano group in an octahedral geometry. These hydrido-(enolato)ruthenium(II) complexes catalyse Michael and Knoeevenagel reactions under neutral and mild conditions. The Royal Society of Chemistry 1999.
- Hirano, Masafumi,Takenaka, Atsushi,Mizuho, Yuji,Hiraoka, Makiko,Komiya, Sanshiro
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p. 3209 - 3216
(2007/10/03)
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- N-bonded enolatorhenium(I) complexes having dimethylphenylphosphine ligands as active key intermediates in catalytic Knoevenagel and Michael reactions
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Enolatorhenium(I) complexes cis-Re(NCCRCO2R′)(NCCHRCO2R′)(PMe 2Ph)4 (R=H, R′=Me (2a); R=H, R′=Et (2b); R=H, R′=n-Bu (2c); R=Me, R′=Et (2d)) are prepared by the reaction of ReH(N2)(PMe2Ph)4 (1) with alkyl cyanoalkyl carboxylate. X-ray structure analysis of 2b shows that it has an octahedral Re geometry, where mutually cis enolato and ester ligands bind to the rhenium via cyano groups. Reaction of 2b with benzaldehyde gives Re(NCCHCO2Et)[NC(EtO2C)C=CHPh]-(PMe2Ph) 4 (4), which is also derived from the ligand exchange reaction of 2b with ethyl (E)-2-cyano-3-phenylpropenoate. These rhenium(I) complexes 1, 2, and 4 catalyze Knoevenagel and Michael reactions under neutral and mild conditions. A possible mechanism for the Knoevenagel reaction has been proposed.
- Hirano, Masafumi,Hirai, Miwa,Ito, Yuji,Tsurumaki, Tsutomu,Baba, Atsushi,Fukuoka, Atsushi,Komiya, Sanshiro
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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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- UTILISATION DE MEMBRANES ECHANGEUSES D'IONS EN ELECTROSYNTHESE ORGANIQUE.
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The addition of carbon acids to acrylonitrile or methyl acrylate can be initiated by means of bases electrogenerated in aprotic media in the absence of supporting-electrolyte, at the interface between a porous cathode and a solid polymer electrolyte.The consumption of electricity is below 1E-2 faraday per mole.Putting to the test donors with decreasing acidity (2-nitropropane, malononitrile, diethyl malonate, ethyl cyanacetate, 2-methylcyclohexanone, fluorene) allows to estimate the basicity level that can be reached at such an interface.The influence of differentfactors (such as the nature of the ion exchange membrane, the basicity of the second side of the membrane, the presence of a probase) on the rates and yields of the reactions has been investigated.
- Raoult, Eugene,Sarrazin, Jean,Tallec, Andre
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p. 5299 - 5306
(2007/10/02)
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