- Clay catalysis: Storks alkylation and acylation of cyclohexanone without isolation of enamine
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Cyclohexanone and morpholine in the presence of KSF under azeotropic distillation gave 1-morpholinocyclohexane which is alkylated or acylated in situ without isolation of the enamine. The overall yield of these Stork's reactions are better or equivalent to those obtained by isolation of the enamine.
- Hammadi,Villemin
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- Michael addition of ketone enolates to α,β-unsaturated esters or amides in a one-pot procedure: Highly efficient effect of lithium salt generated in situ on organotin enolate
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Michael addition of a metal ketone enolate to an α,β-unsaturated ester is thermodynamically disfavored, and thus, isolated metal enolates with an equimolar amount of Lewis acids or additives are usually required. This work describes the methodology of one
- Yasuda, Makoto,Shigeyoshi, Yusuke,Shibata, Ikuya,Baba, Akio
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- Efficient synthesis of ω-functionalized nonanoic acids
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Starting from cyclohexanone and acrylonitrile, a four-step synthesis of the title open-chain C9 compounds is reported. An improved protocol for cyanoethylation of cyclohexanone in the presence of a catalytic amount of cyclohexylamine afforded 3-(2-oxocyclohexyl)propanenitrile (1) in 92% yield. Cyclohexaneperoxycarboxylic acid (CHPCA) is introduced as a highly efficient reagent in the Baeyer-Villiger rearrangement of 1, yielding over 90% of 2. Pyrolysis of 2 afforded under optimized conditions 3 in 92% yield and 99% regioisomeric purity, otherwise a mixture of three unsaturated isomeric ω-cyano nonenoic acids 3, 10 and 11 is obtained. Partial hydrogenation of 3 allowed the isolation of 4 in 90% yield. Hydrogenation of 4 at elevated hydrogen pressure gave 9-aminononanoic acid (5), whereas hydrolysis of 4 led to 1,9-nonanedioic acid (azelaic acid, 6). Both, 5 and 6 are valuable C9 monomers for the preparation of polyamides with specific properties.
- Cotarca,Delogu,Maggioni,Nardelli,Bianchini,Sguassero
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- Room-temperature, acid-catalyzed [2+2] cycloadditions: Suppression of side reactions by using a flow microreactor system
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Added value: The [2+2] cycloaddition of silyl enol ethers with α,β-unsaturated esters, catalyzed by the superstrong acid triflic imide (Tf2NH), at room temperature in a flow microreactor system is reported. The micororeactor method achieves the [2+2] cycloaddition of unstable silyl enol ethers and acrylates, which is unsuccessful in batch reactors, even at room temperature. Copyright
- Kurahashi, Kei,Takemoto, Yoshiji,Takasu, Kiyosei
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- Intramolecular Photoaddition of Alkenes to Chiral 1,3-Dioxin-4-ones: Evidence for Effect of Pyramidalization on the Facial Selectivity
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Intramolecular photoaddition of alkenes to chiral 1,3-dioxin-4-ones 5 present, for the first time, examples with high facial selectivity in which the addition proceeds preferentially from the less exposed side (b-side) under kinetic control conditions.This unprecedented facial selectivity cannot be explained only on the basis of steric effects; however, it is consistent with the direction of pyramidalization in structure 3.It can be concluded that the geometry of the pyramidalized Cβ in the triplet excited dioxinones plays an important role in defining the facial selectivity in this reaction.However, steric effect cannot be neglected in rationalizing the facial selectivity as found by comparing the facial selectivity obtained in the irradiation of the studied compounds.
- Haddad, Nizar,Abramovich, Zehavit
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- A de novo Synthesis of Oxindoles from Cyclohexanone-Derived γ-Keto-Ester Acceptors Using a Desaturative Amination-Cyclization Approach
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Here we report a desaturative approach for oxindole synthesis. This method uses simple ethyl 2-(2-oxocyclohexyl)acetates and primary amine building blocks as coupling partners. A dual photoredox cobalt manifold is used to generate a secondary aniline that, upon heating, cyclizes with the pendent ester functionality. The process operates under mild conditions and was applied to the modification of several amino acids, the blockbuster drug mexiletine, as well as the formation of dihydroquinolinones.
- Caldora, Henry P.,Govaerts, Sebastian,Dighe, Shashikant U.,Turner, Oliver J.,Leonori, Daniele
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supporting information
p. 4272 - 4278
(2021/08/13)
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- A practical synthetic route to enantiopure 6-substituted cis-decahydroquinolines
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Starting from 4-substituted cyclohexanones, a practical synthetic route to enantiopure 6-substituted cis-decahydroquinolines has been developed, the key steps being a stereoselective cyclocondensation of an unsaturated δ-keto ester derivative with (R)-phenylglycinol and the stereoselective hydrogenation of the resulting tricyclic oxazoloquinolone lactams.
- Amat, Mercedes,Navio, Laura,Llor, Nuria,Molins, Elies,Bosch, Joan
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supporting information; experimental part
p. 210 - 213
(2012/03/10)
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- Ring contraction/transannular cyclization of chiral bicyclo[3.3.1] nonanediones mediated by thallium(III) nitrate
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The reaction of several chiral bicyclo[3.3.1]nonane ketones mediated by thallium(III) nitrate to afford ring contraction products is investigated. The effect of solvent on the oxidation is discussed, and the use of thallium(III) nitrate for the oxidative
- Kubilius, Rytis,Bagd?inas, Gintautas,Butkus, Eugenijus
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experimental part
p. 346 - 348
(2011/02/28)
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- Preparation of sixteen 3-hydroxy-4- and 7-hydroxy-1-hydrindanones and 3-hydroxy-4- and 8-hydroxy-1-hydroazulenones
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3-Hydroxyoctahydro-4H-inden-4-ones and 7-hydroxyoctahydro-1H-inden-1-ones (1, 2 and 3, 4, respectively), as well as the homologous 3-hydroxyoctahydro- 4(1H)-azulenones (5, 6) and 8-hydroxyoctahydro-1(2H)-azulenones (7, 8), were prepared diastereoselective
- Tsantali, Georgia G.,Dimtsas, John,Tsoleridis, Constantinos A.,Takakis, Ioannis M.
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p. 258 - 265
(2007/10/03)
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- Palladium-catalyzed intramolecular hydroalkylation of alkenyl- β-keto esters, α-aryl ketones, and alkyl ketones in the presence of Me 3SiCl or HCI
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Reaction of 3-butenyl β-keto esters or 3-butenyl α-aryl ketones with a catalytic amount of [PdCl2(CH3CN)2] (2) and a stoichiometric amount of Me3SiCl or Me3SiCl/ CuCl2 in dioxane at 25-70°C formed 2-substituted cyclohexanones in good yield with high regioselectivity. This protocol tolerated a number of ester and aryl groups and tolerated substitution at the allylic, enolic, and cis and trans terminal olefinic positions. In situ NMR experiments indicated that the chlorosilane was not directly involved in palladium-catalyzed hydroalkylation, but rather served as a source of HCl, which presumably catalyzes enolization of the ketone. Identification of HCl as the active promoter of palladium-catalyzed hydroalkylation led to the development of an effective protocol for the hydroalkylation of alkyl 3-butenyl ketones that employed sub-stoichiometric amounts of 2, HCl, and CuCl2 in a sealed tube at 70°C.
- Han, Xiaoqing,Wang, Xiang,Pei, Tao,Widenhoefer, Ross A.
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p. 6333 - 6342
(2007/10/03)
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- Palladium-catalyzed intramolecular hydroalkylation of unactivated olefins with dialkyl ketones
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(Matrix presented) Treatment of 3-butenyl heptyl ketone with substoichiometric amounts of PdCl2(CH3CN)2 (10 mol%), HCl (0.1 equiv), and CuCl2 (0.3 equiv) in dioxane at 70°C for 12 h in a sealed tube formed 2-hexylcyclohexanone in 77% isolated yield. A number of alkyl 3-butenyl ketones underwent hydroalkylation under these conditions to form 2-substituted cyclohexanones in moderate to good yield.
- Wang, Xiang,Pei, Tao,Han, Xiaoqing,Widenhoefer, Ross A.
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p. 2699 - 2701
(2007/10/03)
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- Michael addition of stannyl ketone enolate to α,β-unsaturated esters catalyzed by tetrabutylammonium bromide and an ab initio theoretical study of the reaction course
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Michael addition of stannyl ketone enolates to α,β-unsaturated esters was accomplished in the presence of a catalytic amount of tetrabutylammonium bromide (Bu4NBr). Other typical systems using lithium enolate or silyl enolate with catalysts (TiCl4 or Bu4NF) failed to give the desired products. The bromide anion from Bu4NBr coordinates to the tin center in enolate to accelerate the conjugate addition where a five-coordinated tin species was generated. The coordination of the bromide anion significantly raises the HOMO level of tin enolate and enhances its nucleophilicity. The conjugate addition provides the intermediate Michael adduct, which has an ester enolate moiety, and the adduct immediately transforms to α-stannyl γ-ketoester by keto - enol tautomerization. This step contributes to the stabilization of the product system and leads to a thermodynamically favorable reaction course. An ab initio calculation reveals that the activation energy in the reaction using the bromide anion is lower than that of the reaction without using it. The transition state in either reaction course has a linear structure, not a cyclic one. This system can be applied to a variety of tin enolates and α,β-unsaturated carbonyls involving enoates, enones, and unsaturated amides.
- Yasuda, Makoto,Chiba, Kouji,Ohigashi, Noriyuki,Katoh, Yasuhiro,Baba, Akio
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p. 7291 - 7300
(2007/10/03)
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- Effect of C-ring modifications in benzo[c]quinolizin-3-ones, new selective inhibitors of human 5α-reductase 1
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The synthesis and the inhibition potency of ocatahydro- and decahydrobenzo[c]quinolizin-3-one derivatives 3-7, as new non-steroidal selective inhibitors of human enzyme 5α-reductase type 1, are reported. These compounds differ from the recently reported enzo[c]quinolizin-3-one inhibitors 2 by the presence of a fully or partially saturated C-ring. Compounds 3 and 4, with a double bond in the C-ring, were prepared by sequential rearrangement-annulation of isoxazolines 19 and 20. C-ring saturated compounds 5-7 were prepared by the lewis acid-promoted. Mannich-Michael tandem reaction of Danishefsky diene with the appropriate N-t-Boc iminium ion. Inhibition experiments were carried out in 5αR-1 and 5αR-2 expressed by CHO cells. Among the prepared compounds, octahydrobenzo9c0quinolizin-3-one3, with a double bond at the position 6a-10a, was a potent and selective inhibitor of human 5αR-1 IC50 = 58 nM). The introduction of a tert-butylcarboxyamide at the position 8 compounds 5-7. The extended planarity of the most potent benzo[c]quinolizin-3-ones as well as favorable interactions of the C-ring unsaturation with the enzyme active site could account for the inhibition activity of these compounds. Copyright
- Guarna, Antonio,Occhiato, Ernesto G.,Machetti, Fabrizio,Trabocchi, Andrea,Scarpi, Dina,Danza, Giovanna,Mancina, Rosa,Comerci, Alessandra,Serio, Mario
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p. 1385 - 1393
(2007/10/03)
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- Efficient and scaleable methods for ω-functionalized nonanoic acids: Development of a novel process for azelaic and 9-aminononanoic acids (nylon-6,9 and nylon-9 precursors)
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A new, convergent synthesis and process of the title open-chain C-9 compounds, valuable monomers for preparation of polyamides with specific properties, are discussed. Starting from relatively inexpensive raw materials, for example, cyclohexanone and activated C-3 olefins, the method provides polymer grade co-functionalized nonanoic acids. An improved protocol for cyanoethylation or carbalkoxyethylation of cyclohexanone in the presence of a catalytic amount of primary or secondary amines gave 3-(2-oxo-cyclohexane) propanecarboxylic acid derivatives 1 in high yield. Cyclohexaneperoxycarboxylic acid (CHPCA) is introduced as highly efficient reagent in Baeyer-Villiger rearrangement of 1. Pyrolysis of 2 (EWG = CN) afforded under optimized conditions 3 in high yield and regioisomeric purity, otherwise a mixture of three unsaturated isomeric ω-cyano nonenoic acids is obtained. Partial hydrogenation of unsaturated acids 3 allowed isolation of saturated long-chain difunctionalized acids 4. Hydrolysis of 4 led to 1,9-nonanedicarboxylic acid (azelaic acid) 5, whereas its hydrogenation at elevated pressure gave 9-aminononanoic acid 6. Alternatively, a practical four-step syntehsis of 5 via isolable 7-substituted oxepan-2-one (EWG = COOMe) 2 has been designed and experimentated. The versatile position of 3-(2-oxo-cyclohexane) propanecarboxylic acid derivatives 1 as raw materials for Fine Chemicals is also discussed.
- Cotarca, Livius,Delogu, Pietro,Nardelli, Alfonso,Maggioni, Paolo,Bianchini, Roberto,Sguassero, Stefano,Alini, Stefano,Dario, Roberto,Clauti, Giuliano,Pitta, Giorgio,Duse, Gianpaolo,Goffredi, Fabrizio
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- Antimalarial sulfide, sulfone, and sulfonamide trioxanes
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A series of trioxanes featuring sulfide, sulfone, and sulfonamide substituents in diverse positions has been prepared. Structure-activity relationship (SAR) generalizations highlight two major factors controlling the antimalarial potency of these new chemical entities: (1) the proximity of the sulfur-containing substituent to the crucial peroxide bond and (2) the oxidation state of the sulfur-containing substituent. Generally, sulfones are more antimalarially potent than the corresponding sulfides. Copyright (C) 2000 Elsevier Science Ltd.
- Posner, Gary H.,Maxwell, John P.,O'Dowd, Hardwin,Krasavin, Mikhail,Xie, Suji,Shapiro, Theresa A.
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p. 1361 - 1370
(2007/10/03)
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- Ring-Chain Tautomerism Provides a Route to 7a-Hydroxy-3a-methyl-2,7-dioxoperhydrobenzofuran. Synthesis of the Hydroxy γ-Lactone Substructure of Myrocin and Other Bioactive Natural Products
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(2-Oxocyclohexyl)acetic acid 10 was converted into bicyclic alkoxy γ-lactones 12a-d via intermediate chloro lactone 11 and alkanolysis.Similarly, lactones 15a,b and 18 were prepared.In contrast, simple ring-chain tautomerism directly afforded the title heterocycle 28, a crystalline, stable and welldefined compound.The angular methyl group seems essential for the spontaneous lactonization. 5,5-Dialkoxy-4-oxocarboxylic acids 26a, b without an angular methyl group did not cyclize to bicyclic hydroxy γ-lactones. - Key Words: Hydroxy lactone, 5-membered, (lactol) tautomer / 4-Oxocarboxylic acids / Keto-cyclol tautomerism.
- Langschwager, Wolf,Hoffmann, H. Martin R.
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p. 797 - 802
(2007/10/02)
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- Process for producing octahydrocoumarin or derivative thereof
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For producing octahydrocoumarin or a derivative thereof represented by: wherein R1 to R4 each represents hydrogen or C1-5 alkyl (a) a 3-(2-oxocyclohexyl)propionic acid ester or derivative thereof represented by: where R1 to R4 are as defined above and R5 represents C1-5 alkyl, is reduced at 0-25°C using hydrogen in the presence of a catalyst (e.g. Ru, Rh, Pd, Ph) and optionally a solvent and/or an acid or alkali, thereby to convert the compound of formula (1) to a 3-(2-hydroxycyclohexyl)propionic acid ester or derivative thereof represented by: wherein R1 to R5 are as above and optionally removing e.g. by distillation the alcohol formed; (b) the compound of formula (2) is cyclized at 0-300°C preferably with an acid or alkali as catalyst and with continuous removal of reaction products or alcohol thereby to convert the compound of formula (2) to octahydrocoumarin or a derivative with elimination of an alcohol. The product (3) is usually a mixture of cis- and trans- isomers and is obtained in good yield. It is useful in perfumes.
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- Preparation and Reactivities of (η3-1- and 2-Trimethylsiloxyallyl)Fe(CO2)NO Complexes. Intermediates Functioning as Equivalents of β- and α-Acyl Carbocations and Acyl Carbanions
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(η3-1- and 2-Trimethylsiloxyallyl)Fe(CO)2NO complexes were prepared by the reaction of the corresponding siloxyallylic halides with Bu4N.These complexes reacted with both of carbon nucleophiles and carbon electrophiles preferentially at the less hindered sites of the allylic ligands.In these reactions, (η3-1-trimethylsiloxyallyl)Fe(CO)2NO complexes served as synthetically equivalent synthons for both of β-acyl carbocations and β-acyl carbanions and (η3-2-trimethylsiloxyallyl)Fe(CO)2NO complexes as both of α-acyl carbocations and α-acyl carbanions.The stereochemical courses of the reactions are described.
- Itoh, Keiji,Nakanishi, Saburo,Otsuji, Yoshio
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p. 2965 - 2977
(2007/10/02)
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- Diversity in Modes of Reactions of (η3-1-Trimethylsiloxyallylic)Fe(CO)2NO Complexes. Nucleophilic Addition and Cyclization on the Allylic Ligands
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The titled iron complexes derived from 3-iodo-1-trimethylsiloxypropenes and reacted with carbon nucleophiles such as NaCH(CO2Et)2 to give the corresponding nucleophile addition products in high yields.The addition occurred at the 3-position of the ligands with high regioselectivity.However, the iron complexes derived from 2-alkyl-3-iodo-1-trimethylsiloxypropenes underwent cyclization reaction with the same siloxypropenes to give dihydropyran derivatives.The diversity in the modes of reactions of the iron complexes are discussed.
- Ito, Keiji,Nakanishi, Saburo,Otsuji, Yoshio
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p. 473 - 476
(2007/10/02)
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- INTRAMOLECULAR PHOTOCYCLOADDITIONS ON DIOXOLENONES: AN EFFICIENT METHOD FOR THE SYNTHESIS OF MEDIUM-SIZED RINGS
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The intramolecular photocycloaddition of dioxolenones to simple olefins leads to the formation of six-, seven-, and eight-membered rings in good yields.Asymmetric induction in the formation of cyclooctanes is described.
- Winkler, Jeffrey D.,Hey, John P.,Hannon, Francis J.
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- REACTIVITE COMPAREE DES ISOMERES IMINE ET ENAMINE SILICIES: SYNTHESE ENANTIOSELECTIVE DE L'(OXO-2 CYCLOHEXYL)-3 PROPIONATE DE METHYLE
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The isomerisation process between SiMe3-substituted enamines and imines (N-SiC-Si) is so slow that each isomer is able to react independently.The silicon-substituted (S)-phenylethylamine derivative adds to methyl acrylate and forms, upon hydrolysis, methyl (S)-3-(2-oxocyclohexyl)propane carboxylate.The tautomeric imine leads to the (R)-enantiomer.Surprisingly, in the presence of a Lewis acid, the ring-containing organosilicon-substituted derivatives show lower stereoselectivity than the corresponding tin compounds.
- Fourtinon, Michel,Jeso, Bernard de,Pommier, Jean-Claude
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p. 239 - 246
(2007/10/02)
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- AROMATIC VERSIONS OF CLAISEN REARRANGEMENT OF LACTONIC SILYL ENOLATES - A NOVEL APPROACH TO FURANOSESQUITERPENE FRAMEWORK
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A new route to the decalin systems (14) and (15) is described.The key step for this synthesis is the Claisen rearrangement of furfuryl lactonic silyl enolates (8) and (9) derived from the furfuryl lactones (6) and (7), respectively.
- Nemoto, Hideo,Shitara, Eiki,Fukumoto, Keiichiro,Kametani, Tetsuji
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p. 1911 - 1913
(2007/10/02)
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- Preparation of delta-keto-esters
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Delta-keto-esters such as 4-oxopentane-1-carboxylic acid methyl ester and the like, are prepared in the presence of a primary amine, a Schiff base, or both, by reacting a ketone having at least one hydrogen atom in the alpha position and an alpha-beta unsaturated carboxylic acid ester in the presence of an acid according to the disclosed invention.
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