- The synthesis of cyclohexenone using l-proline immobilized on a silica gel catalyst by a continuous-flow approach
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A facile and convenient method for the synthesis of cyclohexenone compounds was developed using an l-proline immobilized silica gel catalyst combined with a continuous-flow approach. Because of the mild reaction conditions, ease of catalyst recyclability, and product isolation, this reaction approach can potentially be used in a facile scale-up reaction or in industrial applications. the Partner Organisations 2014.
- Zhi, Cong,Wang, Jiaqing,Luo, Bin,Li, Xinming,Cao, Xueqin,Pan, Yue,Gu, Hongwei
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p. 15036 - 15039
(2014/04/17)
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- Organocatalyst-mediated aldolrobinson cascade reactions: A convenient synthesis of substituted cyclohex-2-enones
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A convenient organocatalytic process for the chemoselective synthesis of substituted cyclohex-2-enones was developed. The cascade reaction involves a remarkable Michael addition of an acyclic ketone-based enamine onto unmodified enones. The enamine-mediated aldolRobinson cascade reactions of aromatic and aliphatic aldehydes with acetone produced substituted cyclohex-2-enones in moderate to high yields under mild reaction conditions.
- Wang, Li,Gong, Qing-Ping,Liu, Xiao-Jun,Li, Yong-Hong,Huang, Ping,Wang, Bi-Qin,Zhao, Ke-Qing
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supporting information; experimental part
p. 138 - 139
(2011/04/15)
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- An efficient synthesis of some 5-substituted-3-methyl-2-cyclohexen-1-ones using microwaves
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3-Methyl-2-cyclohexenone and its 5-substituted-derivatives are prepared in high yields and short duration of time, using the microwave irradiation technique by the condensation of ethyl acetoacetate with eight different aldehydes and piperazine.
- Jyothi, Divya,Hari Prasad
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p. 630 - 632
(2008/09/19)
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- Recyclization of 1,4-dihydropyridine derivatives in acidic medium
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The recyclization of 1,4-dihydropyridines in aqueous-alcoholic hydrochloric acid medium proceeds with cleavage of a C-N bond and pyridine ring opening. Cyclohexenone derivatives are formed as a result of the subsequent intramolecular crotonic condensation of the acyclic intermediate. The leaving carbonyl substituents depart simultaneously with recyclization, depending on the acidity of the reaction medium.
- Stupnikova,Petushkova,Muceniece,Lūsis
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- Br?nsted acid-promoted cyclizations of siloxy alkynes with unactivated arenes, alkenes, and alkynes
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In this article, we describe the development of a general concept for the development of new carbon-carbon bond-forming processes, which is based on Br?nsted acid-mediated activation of a siloxy alkyne, followed by efficient interception of the resulting highly reactive ketenium ion by unactivated arenes, alkenes or alkynes. We found that trifluoromethane sulfonimide (HNTf2) proved to be a superior promoter of these reactions compared to a range of other Br?nsted acids. This finding could be attributed to a high acidity of HNTf2 in aprotic organic solvents combined with a low nucleophilicity of the NTf2- anion. Depending on the nature of the nucleophile, the carbocyclizations proceeded either via 6-endo-dig or 5-endo-dig manifolds. In the case of 1-siloxy-1,5-diynes, the cyclizations occurred with a concomitant halide abstraction or arylation.
- Zhang, Liming,Sun, Jianwei,Kozmin, Sergey A.
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p. 11371 - 11380
(2007/10/03)
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- Bronsted acid-promoted cyclizations of siloxyalkynes with arenes and alkenes
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We have described the first Bronsted acid-mediated cyclizations of siloxyalkynes with simple arenes and alkenes to afford substituted tetralone and cyclohexenone derivatives. The most notable aspect of the carbocyclizations involving siloxyalkynes is the ability to employ a range of substrates that are not restricted to those containing electron-rich arenes and alkenes. The key mechanistic feature of the reaction is the generation of a highly reactive ketenium ion upon protonation of siloxyalkyne. We believe that the low nucleophilicty of the counteranion is crucial for enabling the formation and effective interception of this highly reactive intermediate. Copyright
- Zhang, Liming,Kozmin, Sergey A.
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p. 10204 - 10205
(2007/10/03)
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- Serine carbonates
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Serine carbonates of formula I are precursors for organoleptic compounds, masking agents and antimicrobial agents. Further they are alternative substrates for malodor producing enzymes. The symbols in formula I are defined in claim 1.
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- Compounds having protected hydroxy groups
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The present invention relates to compounds with protected hydroxy groups of formula (I) These compounds are precursors for organoleptic agents, such as fragrances, and masking agents and for antimicrobial agents. When activated, the compounds of formula (I) are cleaved and form one or more organoleptic and/or antimicrobial compounds.
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- Compounds having protected hydroxy groups
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The present invention relates to compounds with protected hydroxy groups of formula (I) These compounds are precursors for organoleptic agents, such as fragrances, and masking agents and for antimicrobial agents. When activated, the compounds of formula (I) are cleaved and form one or more organoleptic and/or antimicrobial compounds.
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- Precursors for fragrant ketones and fragrant aldehydes
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The present invention refers to fragrance precursors of formula I for a fragrant ketone of formula II and one or more fragrant aldehydes or ketones of formula III and IV, These fragrance precursors are useful in perfumery, especially in the fine and functional perfumery.
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- Beta-ketoester compounds
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The beta-ketoesters of formula I are useful as precursors for organoleptic compounds, especially for flavors, fragrances and masking agents and antimicrobial compounds.
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- Ketone precursors for organoleptic compounds
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The invention discloses ketones of formula I: wherein, Y is an optionally substituted alkyl, cycloalkyl, or cycloalkylalkyl, wherein each alkyl group is straight or branched and each alkyl and cycloalkyl group is saturated or unsaturated; R1is hydrogen or a C1-6alkyl group that is substituted, saturated or unsaturated, straight or branched; A is a chromophoric substituted aromatic ring or ring system; n is an integer; and with the proviso that formula I is not 2-ethoxy-1-phenyl-ethanone. These compositions are useful for the delivery of organoleptic compounds, especially of flavors, fragrances, masking agents and antimicrobial compounds.
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- Aldol Reaction and Robinson-Type Annelation Catalyzed by Lanthanoid Triisopropoxides
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Lanthanoid triisopropoxides are active catalysts for aldol reactions.Aldehydes give the corresponding β-hydroxyaldehydes at low temperatures in good yields, whereas ketones are less reactive, but form condensation products at high temperatures.Exceptionally, γ- or δ-diketones easily undergo condensation to give five- and six-membered unsaturated ketones in high yields.The lanthanoid propoxides, catalyzing the Michael addition of ketones to α,β-unsaturated ketones, which give δ-diketones, are also good catalysts for the Robinson-type annelation.In these reactions, the catalytic activity of the lanthanum propoxide is higher than those of the heavy lanthanoid propoxides, and is almost comparable to that of sodium isopropoxide.Since aluminum triisopropoxide shows poor activity, the lanthanoid propoxides are considerably basic for trivalent metal alkoxides.
- Okano, Tamon,Satou, Yoshikazu,Tamura, Motoshi,Kiji, Jitsuo
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p. 1879 - 1886
(2007/10/03)
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- Dienediolates of Unsaturated Carboxylic Acids in Synthesis. Synthesis of Cyclohexenones and Polycyclic Ketones by Tandem Michael-Dieckmann Decarboxylative Annulation of Unsaturated Carboxylic Acids.
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Substituted 2-cyclohexenones 4 to 7 and hexahydronaphthalenones and hexahydroindenones 13 to 18 are prepared by tandem Michael-Dieckmann addition of lithium dienediolates of acyclic and alicyclic unsaturated carboxylic acids to the lithium salts of the same or other unsaturated carboxylic acids.
- Aurell, Maria J.,Gavina, Pablo,Mestres, Ramon
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p. 2571 - 2582
(2007/10/02)
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- Dienediolates of unsaturated carboxylic acids in synthesis. Tandem Michael-Dieckmann synthesis of substituted 2-cyclohexenones
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3,5-Disubstituted 2-Cyclohexenones are prepared by tandem Michael-Diekcmann addition of lithium dienediolates of dimethylacrylic and β-methylcinnamic acids to lithium carboxylates of unsaturated carboxylic acids.
- Aurell,Gavina,Gil,Parra,Tortajada,Mestres
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p. 1825 - 1831
(2007/10/02)
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- Process for the preparation of condensation products of acetoacetic esters and aldehydes
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The known condensation reaction of lower alkanoylacetic acid lower alkyl esters with aldehydes catalyzed by amines proceeds safe and in high yields if the amineis an aliphatic tertiary amine. The products are precursors of aromatic amines.
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