- Biosynthesis of polyketide-terpenoid (Meroterpenoid) metabolites andibenin B and andilesin A in aspergillus variecolor
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Incorporation of 13C-labelled acetates and nethionine indicate that andibenin B (1) and andilesin A (5), C25 metabolites of Aspergillus variecolor, are biosynthesised via a mixed polyketide-terpenoid pathway, 18O-Labelling studies, and incorporation of aromatic precursors and mevalonic acids variously labelled with 13C, 2H and 18O provide evidence for the extensive oxidative and other modifications involved in the elaboration of the highly oxygenated polycyclic structures found in these metabolites. The biosynthetic interrelationships among these and other complex meroterpenoid metabolites are discussed.
- Simpson, Thomas J.,Anmed, Salman A.,McIntyre, C. Rupert,Scott, Fiona E.,Sadler, Ian H.
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- Synthesis method of 4,4-dimethoxy-2-butanone
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The invention discloses a synthesis method of 4,4-dimethoxy-2-butanone, wherein the synthesis method comprises the following steps: S1, preparing raw material liquids, wherein the raw material liquid 1 is a sodium methoxide solution, the raw material liquid 2 is a mixed solution of acetone and ethyl formate, and the raw material liquid 3 is concentrated sulfuric acid; S2, building a reactor: carrying out a synthesis reaction by adopting a tangential flow reactor, wherein the total volume of the reactor is 5 L; S3, preparing 4,4-dimethoxy-2-butanone: starting the tangential flow reactor and a diaphragm pump to carry out a synthetic reaction; and S4, post-treatment: neutralizing the solution, filtering, carrying out atmospheric distillation, and carrying out reduced pressure distillation to obtain a 4,4-dimethoxy-2-butanone product. According to the invention, a continuous flow mode is adopted for reaction, so that heat storage of a reaction kettle is effectively avoided, and the operation safety of each part is improved. And meanwhile, a microreactor is adopted to promote mixing of reactions in all steps, so that the reaction rate and the pure product quality are improved, the reaction time is shortened, and the production efficiency of enterprises is improved.
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Paragraph 0017-0037
(2021/11/06)
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- Electronic Asymmetry of an Annelated Pyridyl-Mesoionic Carbene Scaffold: Application in Pd(II)-Catalyzed Wacker-Type Oxidation of Olefins
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The two donor modules of an annelated pyridyl-mesoionic carbene ligand (aPmic) have different σ- and π-bonding characteristics leading to its electronic asymmetry. A Pd(II) complex 1 featuring aPmic catalyzes the oxidation of a wide range of terminal olefins to the corresponding methyl ketones in good to excellent yields in acetonitrile. The catalytic reaction is proposed to proceed via syn-peroxypalladation and a subsequent rate-limiting 1,2-hydride shift, which is supported by kinetic studies. The electronic asymmetry of aPmic renders a well-defined coordination sphere at Pd. The favored arrangement of reactants on the metal center features an olefin trans to the pyridyl module and a tbutylperoxide trans to the carbene. This arrangement gains added stability by the π-delocalization paved by the compatible orbitals on Pd, the pyridyl module, and the olefin that is perpendicular to the Pd(aPmic) plane. The π-interactions are absent in an alternate arrangement wherein the olefin is trans to the carbene. Density functional theory studies reveal the matching orbital overlaps responsible for the preferred arrangement over the other. This work provides an orbital description for the electronic asymmetry of aPmic.
- Bera, Jitendra K.,Dutta, Indranil,Kunnikuruvan, Sooraj,Reshi, Noor U Din,Saha, Sayantani,Yadav, Suman
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p. 11385 - 11393
(2020/11/23)
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- CuII-Catalyzed Oxidative Formation of 5-Alkynyltriazoles
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In an alcoholic solvent under the catalysis of Cu(OAc)2?H2O, organic azide and terminal alkyne could oxidatively couple to afford 5-alkynyl-1,2,3-triazole (alkynyltriazole) at room temperature under an atmosphere of O2 in a few hours. The involvement of 1,5-diazabicyclo[4.3.0]non-5-ene (DBN) is essential, without which the redox neutral coupling instead proceeds to produce 5-H-1,2,3-triazole (protiotriazole) as the major product. Therefore, DBN switches the redox neutral coupling between terminal alkyne and organic azide, the copper-catalyzed “click” reaction to afford protiotriazole, to an oxidation reaction that results in alkynyltriazole. The organic base DBN is effective in accelerating the copper(II)-catalyzed oxidation of terminal alkyne or copper(I) acetylide, which is intercepted by an organic azide to produce alkynyltriazole. The proposed mechanistic model suggests that the selectivity between alkynyl- and protiotriazole, and other acetylide or triazolide oxidation products is determined by the competition between copper(I)-catalyzed redox neutral cycloaddition and copper(II)/O2-mediated acetylide oxidation after the formation of copper(I) acetylide.
- Liu, Peiye,Brassard, Christopher J.,Lee, Justin P.,Zhu, Lei
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supporting information
p. 380 - 390
(2020/01/24)
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- Tropylium salts as efficient organic Lewis acid catalysts for acetalization and transacetalization reactions in batch and flow
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Acetalization reactions play significant roles in the synthetically important masking chemistry of carbonyl compounds. Herein we demonstrate for the first time that tropylium salts can act as organic Lewis acid catalysts to facilitate acetalization and transacetalization reactions of a wide range of aldehyde substrates. This metal-free method works efficiently in both batch and flow conditions, prompting further future applications of tropylium organocatalysts in green synthesis.
- Lyons,Crocker,Enders,Nguyen
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supporting information
p. 3993 - 3996
(2017/09/08)
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- New process for preparing pyrazole carboxylic acid derivatives
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The present invention relates to a method for preparing a pyrazole carboxylic acid derivative. More particularly, the present invention relates to a novel method for preparing 1-alkyl-3-haloalkyl pyrazole-4-carboxylic acid represented by chemical formula (I) and useful for an intermediate for the preparation of a pyrazole carboxanilide-based sterilizing agent. In chemical formula (I), R_1 represents a C1-C3 lower alkyl group, R_2 represents any one of CHF_2, CF_3, CHCl_2 and CCl_2.COPYRIGHT KIPO 2017
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Paragraph 0047; 0065-0070
(2017/04/03)
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- Method for preparing 2-chloro-4-methylpyridine-3-carbonitrile
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The invention discloses a method for preparing 2-chloro-4-methylpyridine-3-carbonitrile. The method comprises the following steps: at -20 DEG C to 50 DEG C, a hydrogen chloride solution is used for treating raw materials containing 4,4-dicyano-3-methyl-3-butenal dimethyl acetal. 2-chloro-4-methylpyridine-3-carbonitrile whose HPLC purity reaches 99% or above can be conveniently obtained, which has important meanings for subsequent preparation of high purity 2-chloro-4-methylpyridine-3-carbonitrile and nevirapine; the method has the advantages of short process route, simple operation, high yield, low cost, etc., a highly toxic product phosphorous oxychloride is avoided, discharge of waste water is reduced, and the method is very suitable for industrial production.
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Paragraph 0040; 0042
(2016/11/14)
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- Palladium-catalyzed aerobic oxidation of terminal olefins with electron-withdrawing groups in scCO2
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Product control of palladium-catalyzed aerobic oxidation of terminal olefins with electron-withdrawing groups can be achieved through modifying reaction conditions. When the oxidant, such as CuCl2/O2, benzoquinone/O2 or O2, was present in scCO2, aerobic oxidation of terminal olefins goes smoothly. With enough MeOH and sufficient oxygen, acetalization preponderated over cyclotrimerization, while with little MeOH as co-solvent in scCO2 or no MeOH in DMF and an appropriate pressure of O2, cyclotrimerization of terminal olefins became the dominated reaction. When oxygen is absent and triethylamine was added into the reaction system, palladium-catalyzed C-N bond formation occurs to produce β-amino acid derivatives as the sole product.
- Jiang, Huan-Feng,Shen, Yan-Xia,Wang, Zhao-Yang
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p. 508 - 514
(2008/03/28)
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- Pd(II)-catalyzed acetalization of terminal olefins with electron-withdrawing groups in supercritical carbon dioxide: selective control and mechanism
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Pd(II)-catalyzed acetalization of terminal olefins with electron-withdrawing groups was carried out smoothly in supercritical carbon dioxide under oxygen atmosphere when polystyrene-supported benzoquinone (PS-BQ) or CuII (CuI) chloride was employed as cocatalyst. The higher selectivity was achieved, without any chlorinated by-product detected, when using PS-BQ instead of CuII (or CuI) chloride. PS-BQ could be recycled with excellent catalytic activity remaining after each simple filtration. Chlorine ion was demonstrated to be a promoter. The different acetalization mechanisms were revealed by the subtle relationship of chlorine ion and benzoquinone (BQ) to the catalytic activity of PdCl2/PS-BQ, PdII-CuCl2 or Pd(OAc)2/PS-BQ.
- Wang, Zhao-Yang,Jiang, Huan-Feng,Ouyang, Xiao-Yue,Qi, Chao-Rong,Yang, Shao-Rong
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p. 9846 - 9854
(2007/10/03)
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- Imidazo[1,2-a]pyrimidines as functionally selective and orally bioavailable GABAAα2/α3 binding site agonists for the treatment of anxiety disorders
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A series of high-affinity GABAA agonists with good oral bioavailability in rat and dog and functional selectivity for the GABA Aα2 and -α3 subtypes is reported. The 7-trifluoromethylimidazopyrimidine 14g and the 7-propan-2-olimidazopyrimidine 14k are anxiolytic in both conditioned and unconditioned animal models of anxiety with minimal sedation observed at full BZ binding site occupancy.
- Goodacre, Simon C.,Street, Leslie J.,Hallett, David J.,Crawforth, James M.,Kelly, Sarah,Owens, Andrew P.,Blackaby, Wesley P.,Lewis, Richard T.,Stanley, Joanna,Smith, Alison J.,Ferris, Pushpinder,Sohal, Bindi,Cook, Susan M.,Pike, Andrew,Brown, Nicola,Wafford, Keith A.,Marshall, George,Castro, José L.,Atack, John R.
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- Synthesis and SAR of highly potent and selective dopamine D 3-receptor antagonists: 1H-Pyrimidin-2-one derivatives
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The synthesis and SAR of novel highly potent and selective dopamine D 3-receptor antagonists based on a 1H-pyrimidin-2-one scaffold are described. A-690344 antagonized PD 128907-induced huddling deficits in rat (ED50 6.1 mg/kg po), a social interaction paradigm.
- Geneste, Herve,Backfisch, Gisela,Braje, Wilfried,Delzer, Juergen,Haupt, Andreas,Hutchins, Charles W.,King, Linda L.,Kling, Andreas,Teschendorf, Hans-Juergen,Unger, Liliane,Wernet, Wolfgang
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p. 490 - 494
(2007/10/03)
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- Direct organocatalytic hydroalkoxylation of α,β-unsaturated ketones
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The direct addition of a variety of alcohols to in situ activated olefins was observed in the presence of mild bifunctional amine/acid catalysts. Unlike existing methods, the reactions proceed at room temperature and in the absence of transition metals. The use of simple commercially available catalysts, amines and acids makes this an attractive method for the preparation of β-alkoxy ketones, which are prevalent targets and intermediates in organic synthesis.
- Ramachary, Dhevalapally B.,Mondal, Rumpa
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p. 7689 - 7693
(2007/10/03)
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- Ozonolysis of 1,4-cyclohexadienes in the presence of methanol and acid. Mechanism and intermediates in the conversion of 1,4-cyclohexadiene derivatives to β-keto esters
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Conditions for the preparation of β-keto esters directly from 1,4-cyclohexadiene derivatives are described. This procedure is a further step in the application of the synthetic methodology, which consists of the combination of Birch reduction of available benzene derivatives followed by ozonolysis. In this work, the syntheses of derivatives of dimethyl γ-keto-α-aminoadipate and dimethyl β-keto glutamate from the corresponding 1,4-cyclohexadiene derivatives are described. The latter compounds are prepared from phenylalanine and phenylglycine, respectively. The study of the ozonolysis of simple alkyl derivatives of 1,4-cyclohexadiene in the presence of methanol, both in the presence and absence of acid, helped to establish the mechanism of this reaction. The proximity of the two double bonds, which are cleaved, leads to the intermediate formation of 1,2-dioxolane derivatives that could be identified by NMR spectroscopy. It is shown that regardless of the regioselectivity of the cleavage of the primary ozonide, which is formed, all 1,2-dioxolane derivatives can lead to β-keto esters. This is due to the equilibrium between these dioxolanes in the presence of methanol and acid.
- Gbara-Haj-Yahia, Isra,Zvilichovsky, Gury,Seri, Noa
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p. 4135 - 4139
(2007/10/03)
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- Method of preparing sodium formyl acetone and 4,4-dimethoxy-2-butanone
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The present invention provides a method of preparing sodium formyl acetone using acetone, methyl formate and sodium methoxide as raw materials. A mixture consisting of an acetone and a methyl formate is supplied to a methanol solution of sodium methoxide, or an acetone and a methyl formate are separately supplied simultaneously to the methanol solution of sodium methoxide. The resultant mixture is sufficiently stirred over a predetermined period of time so as to carry out the reaction to form sodium formyl acetone. Also provided is a method of preparing 4,4-dimethoxy-2-butanone. In this method, the reaction mixture obtained in the reaction to form sodium formyl acetone is directly charged into a reaction vessel simultaneously with sulfuric acid to neutralize and acetalize sodium formyl acetone contained in the reaction mixture so as to obtain 4,4-dimethoxy-2-butanone.
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- Chlorination of α,β-Unsaturated Ketones and Esters in the Presence of Acid Scavengers
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The chlorination of a series of α,β-unsaturated ketones and esters by Cl2 in CH3OH, with and without acid scavengers such as N-chlorosuccinimide (NCS), pyridine and 2,6-lutidine, is described.Methyl vinyl ketone and cyclohex-2-enone have also been chlorinated in ethanol.Mixtures of Markovnikov(M) and anti-Markovnikov(AM) methoxy chlorides and dichlorides are formed in most cases; phenyl vinyl ketone gives no M products in the absence of pyridine, M methoxy chloride is not formed with (E)-4-chlorobut-3-en-2-one under any conditions, pyridine has no effect on the product ratios and methyl 3-chlorobut-2-enoate forms only dichloride.Chlorination of the ketones in the presence of the pyridines results in a significant increase in the M regioisomer (except for methyl isopropenyl ketone and the ketones mentioned), giving M : AM ratios which are similar to the corresponding esters.Ratios for the esters are not affected significantly by pyridine.We ascribe the effect of the pyridine bases to the elimination of acid and the acid-catalysed mechanism, permitting the chlorination to occur via a carbon-carbon ?-bond (chloronium ion) mechanism.The rate of chlorination of methyl vinyl ketone is retarded by pyridine but is still considerably faster than methyl acrylate.NCS, in contrast to N-bromosuccinimide (NBS) reported previously, has no effect on the M : AM ratio.The chlorination of methyl vinyl ketone with NCS and HCl gives markedly different results from Cl2.
- Heasley, Victor L.,Elliott, Stephen L.,Erdman, Paul E.,Figueroa, Daphne E.,Krosley, Kevin W.,et al.
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p. 393 - 399
(2007/10/02)
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- Crossed aldol-type reactions catalyzed by rhodium complexes
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Crossed aldol-type reactions of enol trimethylsilyl ethers with aldehydes and ketones are smooth when carried out with a catalytic amount of a rhodium complex, Rh4(CO)12 or X (X=PF6 and ClO4; COD=cycloocta-1,5-diene, DPPB=1,4-bis(diphenylphosphino)butane), under neutral conditions.A suitable catalyst enables the isolation of three different types of aldol reaction product, β-trimethylsiloxy ketones, β-hydroxy ketones, and α,β-unsaturated ketones.Rh4(CO)12 and ClO4 also catalyze the reaction of enol trimethylsilyl ethers with acetals or ketals, whereas PF6 does not.When ClO4 is used as the catalyst, this type of aldol reaction is extended to the one-pot synthesis of trisubstituted furans from enol trimethylsilyl ether and α-trimethylsiloxy acetal.
- Sato, Susumu,Matsuda, Isamu,Izumi, Yusuke
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p. 223 - 238
(2007/10/02)
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- ALDOL-TYPE REACTIONS BETWEEN TRIMETHYLSILYL ENOL ETHERS AND ACETALS WITH THE AID OF RHODIUM COMPLEX
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Aldol type reactions of trimethylsilyl enol ethers with acetals, ketals and orthoesters are successfully performed with the aid of a catalytic amount of rhodium complex Rh4(CO)12 or (Rh(COD)(DPPB))(1+)*ClO4(1-), under neutral conditions.
- Sato, Susumu,Matsuda, Isamu,Izum, Yusuke
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p. 6657 - 6660
(2007/10/02)
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- DERIVATIVES OF BIACETYLENE. XLV. REACTION OF BIACETYLENE AND 1-METHOXY-1-BUTEN-3-YNE WITH DIETHYLENE GLYCOL
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The nucleophilic addition of diethylene glycol to biacetylene and methoxybutenyne and the electrophilic reaction of methoxybutenyne with diethylene glycol were investigated.In the presence of alkali two molecules of diethylene glycol add to biacetylene and methoxybutenyne.In the presence of mercury sulfate and water the reaction leads to the formation of a linear β-keto acetal.
- Vavilova, A. N.,Trofimov, B. A.,Volkov, A. N.
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p. 228 - 230
(2007/10/02)
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- A HIGHLY DIASTEREOSELECTIVE SYNTHESIS OF DL-OLEANDROSE
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Racemic oleandrose (2,6-dideoxy-3-O-methyl-arabino-hexose) has been obtained starting from the Diels-Alder adduct between 4-methoxy-3-buten-2-one and isobutyl vinyl ether, which was converted into a mixture of the isobutyl β- and α-oleandrosides through hydroboration-oxidation.The latter reaction is highly diastereoselective since attack by borane takes place exclusively anti to the OMe group; none of the diastereoisomeric cymarosides are formed.The only side-products are small amounts of the isobutyl β- and α-amicetosides formed by a demethoxylation occuring during the hydroboration step.
- Berti, G.,Catelani, G.,Colonna, F.,Monti, L.
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p. 3067 - 3072
(2007/10/02)
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- Chemistry of enol ethers. LI. Reaction of vinyl silyl ethers with orthoformic esters
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The silyl ethers of enolic forms of ketones react with orthoformates in the presence of zinc chloride at catalyst to form β-ketoacetals.The analogous reaction with the silyl ethers of enolic forms of aldehydes leads to the formation of the tetraacetals of 1,3-dialdehydes.
- Makin, S. M.,Kruglikova, R. I.,Popova, T. P.,Tagirov, T. K.
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p. 630 - 634
(2007/10/02)
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- SPECIFIC SOLVATION OF β-KETOALDEHYDES. PART II. HYDROXYLIC SOLVENTS
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Solvation of β-ketoaldehydes, RCOCH2CHO (R = Me, Et, i-Pr, t-Bu and Ph) was investigated in water and alcohols (MeOH, EtOH, i-PrOH and t-BuOH).In alcohols influence of R on the degree of solvation (hemiacetal formation) was observed.In t-BuOH solvation does not occur, whereas in water has no influence on this process (gem.-diol formation).In alcohols the degree of solvation decreases when passing from MeOH to i-PrOH.In these solvents, in addition to hemiacetal, formation of β-alkoxyvinyl ketone was observed.In all investigated solvents the presence of E-enol was stated.
- Terpinski, Jacek,Zajaczkowska-Terpinska, Ewa
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