- Functionalized α-oximinoketones as building blocks for the construction of imidazoline-based potential chiral auxiliaries
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Functionalized α-oximinoketones with β-alkoxy, β-alkyl, and β-sulfenyl groups were used as efficient synthons for the preparation of chiral 1-acyl-4-imidazolin-2-ones and 1-acylimidazolidin-2-ones. For the preparation of the former heterocycles, α-oximinoketones were transformed into their respective imidazole N-oxides by neutral treatment with a chiral triazine, followed by reaction with acetic or propionic anhydrides to furnish the desired chiral 1-acetyl- or 1-propionyl-4-imidazolin-2-ones in moderate overall yields. Upon palladium hydroxide-catalyzed hydrogenation, these series were converted into their corresponding 1-acylimidazolidin-2-ones in high diastereoisomeric ratios. Thus, these novel chiral 1-acetyl- and 1-propionyl-imidazolidin-2-ones were obtained with a variety of alkyl groups at the C-4 and C-5 positions of the heterocycle, through a three-step methodology, and can be applied as new potential chiral auxiliaries.
- Gutiérrez, Rsuini U.,Rebollar, Araceli,Bautista, Rafael,Pelayo, Vanessa,Várgas, José Luis,Montenegro, Mabel M.,Espinoza-Hicks, Carlos,Ayala, Francisco,Bernal, Pablo M.,Carrasco, Cuauhtemoc,Zepeda, L. Gerardo,Delgado, Francisco,Tamariz, Joaquín
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p. 230 - 246
(2015/03/04)
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- Heterobimetallic Pd-Sn catalysis: Michael addition reaction with C-, N-, O-, and S-nucleophiles and in situ diagnostics
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An efficient Michael addition reaction of differently substituted enones with carbon, sulfur, oxygen, and nitrogen nucleophiles has been achieved by a new heterobimetallic "Pd-Sn" catalyst system. The nature of the catalytically relevant species and their
- Das, Debjit,Pratihar, Sanjay,Roy, Sujit
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p. 2430 - 2442
(2013/04/23)
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- Acidic ionic liquid [NMP]H2PO4 as dual solvent-catalyst for synthesis of β-alkoxyketones by the oxa-Michael addition reactions
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Acidic ionic liquid N-methyl-2-pyrrolidonium dihydrogen phosphate [NMP]H2PO4 was prepared and used as efficient catalyst and reaction medium to synthesize β-alkoxyketones by the oxa-Michael addition reactions for the first time. The
- Guo, Hui,Li, Xia,Wang, Jun-Liang,Jin, Xiao-Han,Lin, Xian-Fu
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experimental part
p. 8300 - 8303
(2010/11/05)
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- Synthesis of novel β-functionalized α-oximinoketones via hetero-Michael addition of alcohols and mercaptans to enones
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A new methodology has been developed for the preparation of β-alkoxy and β-sulfenyl ketones by hetero-Michael addition of the corresponding alcohols and thiols to enones under acidic and basic conditions. The direct conversion of enones into β-alkoxy and
- Bernal, Pablo,Tamariz, Joaquín
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p. 2905 - 2909
(2007/10/03)
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- The ionic liquid ethyltri-n-butylphosphonium tosylate as solvent for the acid-catalysed hetero-Michael reaction
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A new and convenient method for the acid-catalysed Michael addition reactions of alcohols, thiols and amines to methyl vinyl ketone has been developed using the ionic liquid ethyltri-n-butylphosphonium tosylate. The reaction conditions are mild and obviat
- Karodia, Nazira,Liu, Xihan,Ludley, Petra,Pletsas, Dimitrios,Stevenson, Grace
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p. 11039 - 11043
(2007/10/03)
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- Novel amine-catalysed hydroalkoxylation reactions of activated alkenes and alkynes
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Substoichiometric loadings of DBU catalyse the efficient 1,4-addition of alcohols and non-nucleophilic amines such as pyrrole to activated alkenes; the application of this methodology in a one-pot synthesis of a natural product, and as a novel strategy for the synthesis of mono-protected 1,3-carbonyl compounds is reported.
- Murtagh, Julie E.,McCooey, Seamus H.,Connon, Stephen J.
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p. 227 - 229
(2007/10/03)
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- Rhodium-catalyzed addition of alcohols to terminal enones
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[Rh(COD)(OMe)]2 was found to catalyze the addition of aliphatic and aromatic alcohols with terminal enones to afford β-alkoxyketones in high yields.
- Farnworth, Marc V.,Cross, Michael J.,Louie, Janis
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p. 7441 - 7443
(2007/10/03)
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- Synthesis of hindered functionalized ethers via high-pressure addition of alcohols to acrylic compounds
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The phosphine-catalyzed 1,4-addition of alcohols to activated alkenes is studied from a synthetic point of view. α- or β-Substituted acrylic compounds react sluggishly or not at all. In this case, high-pressure activation can remove steric inhibition leading to good yields of the corresponding ethers. Reactions involving crotonic compounds (hindered β reaction center) show higher pressure dependence than the corresponding additions of alcohols to methacrylic analogs (free β reaction center). This is in agreement with the concept that sterically demanding reactions show enhanced sensitivity to pressure. The result, obviously, is of high synthetic value as pressure may be capable of removing steric inhibition.
- Jenner, Gérard
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p. 4807 - 4810
(2007/10/03)
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- γ-Ray-induced reduction of sterically hindered alkyl carboxylates with trichlorosilane in the presence of hydrogen chloride. Two-step mechanism for the formation of alkanes via the alkyl chloride
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γ-Irradiation of a mixture of 1-adamantyl acetate and trichlorosilane (TCS) in the presence of hydrogen chloride yields adamantane. The first step of this reaction entails cleavage of the alkyloxygen bond by the action of HCl and TCS to give the alkyl chloride. The chloride, in the second step, is dechlorinated by TCS by a known, free-radical mechanism. t-Amyl and benzyl acetates react analogously to 1-adamantyl acetate in this system to give isopentane and toluene, whereas other primary and secondary alkyl derivatives produce the corresponding dialkyl ethers by a known, free-radical mechanism.
- Oka, Kunio,Nakao, Ren
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- Carbon-13 NMR Spectra of 1,3-Dioxolanes. II - Determination of α, β and γ Parameters for 2- and 4-Methyl Groups in Stereoisomeric Derivatives by the Pattern Molecule Method
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On the basis of the stereochemistry of the 1,3-dioxolane ring, the molecular pattern method allows the establishment of α, β and γ parameters for the 2-Me and 4-Me substituents.Values of α, β and γ additive parameters for the syn and anti 4-Me group in 2,2,4-trisubstituted-1,3-dioxolanes are proposed.The average values of the α, β and γ effects for the 2-Me and 4-Me groups obtained by the molecular pattern method are consistent with those reported from a multiple linear regression analysis.KEY WORDS 1,3-Dioxolane derivatives 13C NMR shift parameters Pattern molecule method
- Espinosa, Antonio,Gallo, Miguel A.,Campos, Joaquin,Enterna, Antonio,Camacho, Encarnacion
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p. 108 - 110
(2007/10/02)
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- REACTION DES VINYLOGUES D'HEMIACETALS ET DE LEURS EQUIVALENTS SYNTHETIQUES SUR LES ETHERS D'ENOLS HETEROCYCLIQUES
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We describe the reaction of hemiacetal vinylogs 2 or their synthetic equivalent with cyclic enol ethers 1 yielding ketoacetals 3.Acidic treatment of these compounds leads to bicyclic heterocycles 8 or enone aldehyde 12 depending on the nature of substituents R1.
- Poirier, Jean-Marie,Dujardin, Gilles
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p. 3337 - 3340
(2007/10/02)
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