- Enantioselective addition of selenosulfonates to α,β-unsaturated ketones
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An organo-catalyzed enantioselective addition of selenosulfonates to α,β-unsaturated ketones was developed for the first time. With a chiral squaramide as an efficient catalyst, the desired α-selenylated ketones were obtained in a good yields with high enantioselectivity up to 89% ee, and good results could be obtained on a gram scale. The products could also be efficiently transformed into useful building blocks with a propenylic stereocenter; the strategy presented in this study may find further applications in organic synthesis.
- Luo, Shilong,Zhang, Nan,Wang, Zhen,Yan, Hailong
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p. 2893 - 2901
(2018/05/03)
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- Method for preparing neophytadiene compounds from fatty acid
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The invention relates to a method for preparing neophytadiene compounds from fatty acid. The method comprises the following steps: firstly preparing lipid-containing ketene from fatty acid in two ways, namely a way a comprising the steps of dehydrogenizing the fatty acid by a deprotonation reagent and then reacting with a vinyl Grignard reagent or vinyl lithium to generate ketene compounds, and a way b comprising steps of activating the fatty acid by carbodiimide reagents, then reacting with dialkyl hydroxylamine or hydrochloride thereof to generate N-alkoxy amide compounds (Weinreb amides) and then reacting with the vinyl Grignard reagent or vinyl lithium to generate the ketene compounds; and finally carrying out reaction on the ketene compounds and an olefination reaction reagent to generate the neophytadiene compounds.
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Paragraph 0013
(2017/08/29)
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- Influence of the chemical structure on odor qualities and odor thresholds in homologous series of alka-1,5-dien-3-ones, alk-1-en-3-ones, alka-1,5-dien-3-ols, and alk-1-en-3-ols
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Odor qualities and odor thresholds in air in homologous series of synthesized alk-1-en-3-ols and alka-1,5-dien-3-ols and their corresponding ketones were evaluated by gas chromatography-olfactometry. In the series of the alk-1-en-3-ols and alk-1-en-3-ones the odor quality changed successively from pungent for the compounds with five carbon atoms via metallic, vegetable-like for the six- and seven-carbon odorants to mushroom-like for the compounds with eight and nine carbon atoms. With further increase in chain length the mushroom-like impression decreased and changed to citrus-like, soapy, or herb-like. In both series, two odor threshold minima were found for the six-carbon and also for the eight- and nine-carbon odorants, respectively. In contrast to this, the odor qualities in the series of the (Z)- and (E)-alka-1,5-dien-3-ols and their corresponding ketones did not change significantly with geranium-like, metallic odors and an increasing mushroom-like odor note with increasing chain length. The lowest thresholds were found for the eight- and nine-carbon (Z)-compounds, respectively.
- Lorber, Katja,Schieberle, Peter,Buettner, Andrea
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p. 1025 - 1031
(2014/03/21)
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- Influence of the chemical structure on odor qualities and odor thresholds in homologous series of alka-1,5-dien-3-ones, alk-1-en-3-ones, alka-1,5-dien-3-ols, and alk-1-en-3-ols
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Odor qualities and odor thresholds in air in homologous series of synthesized alk-1-en-3-ols and alka-1,5-dien-3-ols and their corresponding ketones were evaluated by gas chromatography-olfactometry. In the series of the alk-1-en-3-ols and alk-1-en-3-ones the odor quality changed successively from pungent for the compounds with five carbon atoms via metallic, vegetable-like for the six- and seven-carbon odorants to mushroom-like for the compounds with eight and nine carbon atoms. With further increase in chain length the mushroom-like impression decreased and changed to citrus-like, soapy, or herb-like. In both series, two odor threshold minima were found for the six-carbon and also for the eight- and nine-carbon odorants, respectively. In contrast to this, the odor qualities in the series of the (Z)- and (E)-alka-1,5-dien-3-ols and their corresponding ketones did not change significantly with geranium-like, metallic odors and an increasing mushroom-like odor note with increasing chain length. The lowest thresholds were found for the eight- and nine-carbon (Z)-compounds, respectively.
- Lorber, Katja,Schieberle, Peter,Buettner, Andrea
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p. 1025 - 1031
(2015/04/22)
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- Borohydride-mediated radical addition reactions of organic iodides to electron-deficient alkenes
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Cyanoborohydrides are efficient reagents in the reductive addition reactions of alkyl iodides and electron-deficient olefins. In contrast to using tin reagents, the reaction took place chemoselectively at the carbon-iodine bond but not at the carbon-bromine or carbon-chlorine bond. The reaction system was successfully applied to three-component reactions, including radical carbonylation. The rate constant for the hydrogen abstraction of a primary alkyl radical from tetrabutylammonium cyanoborohydride was estimated to be 4 M-1 s-1 at 25 °C by a kinetic competition method. This value is 3 orders of magnitude smaller than that of tributyltin hydride.
- Kawamoto, Takuji,Uehara, Shohei,Hirao, Hidefumi,Fukuyama, Takahide,Matsubara, Hiroshi,Ryu, Ilhyong
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p. 3999 - 4007
(2014/05/20)
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- Weinreb Amide based building block for convenient access to vinyl ketones
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A new strategy for the synthesis of vinyl ketones has been achieved. Hitherto unknown and easily accessible, β-phenylseleno-N-methoxy-N- methylpropanamide, obtained through two simple reactions, served as a building block for convenient access to vinyl ketones. The N-methoxy-N-methyl amide moiety ensured no overaddition of the Grignard reagent and, hence, the excellent formation of β-phenylseleno ketones; oxidative work-up with hydrogen peroxide provided ready access to the vinyl ketones with concomitant loss of phenylselanol. Georg Thieme Verlag Stuttgart · New York.
- Tiwari, Praveen Kumar,Aidhen, Indrapal Singh
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p. 1777 - 1780
(2013/09/12)
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- Tin-free giese reaction and the related radical carbonylation using Alkyl iodides and cyanoborohydrides
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Tin-free Giese reaction and the related radical carbonylation process proceeded efficiently in the presence of sodium cyanoborohydride and tetrabutylammonium cyanoborohydride. The reaction took place chemoselectively at the carbon-iodine bond but not at the carbon-bromine and carbon-chlorine bonds. The iodine atom transfer followed by hydride reduction of the resulting carbon-iodine bond is proposed as a possible mechanism.
- Ryu, Ilhyong,Uehara, Shohei,Hirao, Hidefumi,Fukuyama, Takahide
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supporting information; experimental part
p. 1005 - 1008
(2009/04/07)
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- A Convenient Synthesis of the Peach Fruit Moth Carposina Niponensis Walk. and of the Douglas Fir Tussock Moth Orgya Pseudotsugata Mc.D. Sex Pheromones and Analogs
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The (Z)- and (E)-isomers of 7-alken-11-ones with chain lengths of 19, 21 and 23 carbon atoms were synthesized.A procedure based on the reaction of alkenylcopper reagents with vinylketones has been elaborated.
- Ramiandrasoa, F.,Descoins, C.
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p. 1989 - 1999
(2007/10/02)
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- The Addition of 1-Lithio-1-(phenylthio)alkanes to 2-(N-Methylanilino)acrylonitrile: An Easy Access to 3-(Phenylthio)ketones and 2-Enones
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A simple and versatile strategy for the synthesis of the title compounds is described.The key-step consists in the addition of 1-lithio-1-(phenylthio)alkanes to 2-(N-methylanilino)acrylonitrile, the nucleophilic phenylthioalkylation of an enol-cation equivalent.Alkylation of the adducts and hydrolysis give 3-(phenylthio)ketones, which can be isolated, or without further purification can be transformed into 2-enones via the well known oxidation-elimination procedure.These reactions are possible with allylic derivatives too, therefore the homologous vinylic compoundscan be prepared by the same way.Pyrolysis of the 1-lithioaminonitriles formed within the first step gives aminonitriles of cyclopropanones via cyclization.
- Ahlbrecht, Hubertus,Ibe, Marcellinus
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p. 210 - 214
(2007/10/02)
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- SYNTHESIS OF 4,6-DIALKYL-1,3-DIOXINS. VERSATILE INTERMEDIATES FOR THE PREPARATION OF (E)-ALKENONES, anti,anti-1,2,3-TRIOLS AND syn-1,3-DIOLS
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The title compounds 4 are prepared from 4-alkyldioxins 2 via a metalation, alkylation sequence.The dialkyl dioxins 4 are thermally labile (providing enones) and undergo highly stereoselective hydroboronation or hydrogenation reactions to provide anti,anti-1,2,3-triols and syn-1,3-diols, respectively.This methodology has been exploited in the synthesis of (+/-)-endo-1,3-dimethyl-2,9-dioxabicyclononane.
- Funk, Raymond L.,Bolton, Gary L.
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p. 1111 - 1114
(2007/10/02)
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- A Convenient and Efficient Unsymmetrical Ketone Synthesis from Acid Chlorides and Alkyl Iodides Catalyzed by Palladium
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Unsymmetrical ketones are prepared in good or excellent yields by a palladium catalyzed coupling reaction of acid chlorides and alkyl iodides meditated by Zn-Cu couple.
- Tamaru, Yoshinao,Ochiai, Hirofumi,Sanda, Fumio,Yoshida, Zen-ichi
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p. 5529 - 5532
(2007/10/02)
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- PHEROMONE 511): SYNTHESE VON UNGESATTINGEN PHEROMONKETONEN AUS ORGYIA PSEUDOTSUGATA (DOUGLAS FIR TUSSOCK MOTH) UND CARPOSINA NIPONENSIS (PEACH FRUIT MOTH) (LEPIDOPTERA)
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The principal (9, 27) and minor (17, 28) sex pheromone components of both, the Douglas fir tussock moth (orgyia pseudotsugata) and the peach fruit moth (Carposina niponensis), have been synthesized in four steps each, using the chain-lengtheningdifunctionalisation of Grignard reagents by reaction with ketenylidenetriphenylphosphorane as the key step.
- Bestmann, Hans Jurgen,Schmidt, Martin
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p. 6171 - 6174
(2007/10/02)
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- CONVENIENT SYNTHESIS OF VINYL KETONES VIA A NEW THREE CARBON HOMOLOGATING AGENT
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Syntheses of vinyl ketones and the himachalene skeleton from 4-phenylthio-N,N-dimethylaminobutyronitrile were demonstrated.
- Tuchinda, Patoomratana,Prapansiri, Vichukorn,Naengchommong, Waree,Reutrakul, Vichai
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p. 1427 - 1430
(2007/10/02)
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- A REGIOSPECIFIC SYNTHESIS OF TRIMETHYLSILYL ENOL ETHERS USING RHODIUM CATALYZED ISOMERIZATION OF β-TRIMETHYLSILYLALLYL ALCOHOLS
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The rhodium catalyzed isomerization of β-trimethylsilylallyl alcohols has been successfully applied for the regiospecific synthesis of trimethylsilyl enol ethers.
- Matsuda, Isamu,Sato, Susumu,Izumi, Yusuke
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p. 2787 - 2790
(2007/10/02)
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- 3-Triethylsilyloxypentadienyllithium, a Versatile 1,3-Diene- or Vinyl ketone-Building Block
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Deprotonation of the 3-trialkylsilyloxy-1,4-diene 3a and subsequent electrophilic substitution of the non-isolated 3-trialkylsilyloxypentadienyllithium 4 gives the α- and γ-products 8 and/or 6 in good yields.Whereas alkylation of 4 proceeds with variable regioselectivity (Table 1) aldehydes and ketones attack preferentially the γ-position of 4 (Table 2).The desired γ-products 6 may be directly subjected to inter- and intramolecular -additions as demonstrated by the reactions 5a(=6d)-->7 and 6h-->19 (schemes 4 and 12).Alternatively, smooth fluoride-promoted silylether-cleavage 6-->11 (Scheme 8) provides a convenient approach to substituted vinyl ketones such as to the natural product 11f (Table 3).The stereoselective conversion 6k-->23 (Scheme 13) implies an endo-selective intramolecular Diels-Alder addition (26-->23) and exemplifies the use of 4 as an equivalent of the hypothetical anion IV.Furthermore, some electrophilic substitutions of the hexadienyllithium 15 have been studied (Scheme 10).
- Oppolzer, Wolfgang,Snowden, Roger L.,Simmons, Dana P.
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p. 2002 - 2021
(2007/10/02)
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