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Artículos de revistas sobre el tema "Encol S.A"

Autor: Grafiati
Publicado: 4 de junio de 2021
Última modificación: 9 de febrero de 2022

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1

Gueyrard, David. "Extension of the Modified Julia Olefination on Carboxylic Acid Derivatives: Scope and Applications". Synlett 29, n.º 01 (16 de octubre de 2017): 34–45. http://dx.doi.org/10.1055/s-0036-1590916.

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This account relates our work in the field of modified Julia olefination to extend this very useful olefination method to carboxylic acid derivatives. Since our preliminary results on lactones in 2005, the reaction has been extended to a large range of derivatives (lactams, imides and anhydrides) through an intra- or intermolecular process leading to a great variety of structures (enol ethers, enamides and exo enol esters). This article will also focus on the application of this methodology for the preparation of biologically interesting compounds and/or total syntheses of natural products such as C-disaccharide, bistramide A, jaspine B and maculalactone B.1 Introduction2 Modified Julia Olefination on Lactones2.1 Methylene Enol Ether Synthesis2.2 Substituted Enol Ether Synthesis2.3 Monofluorinated Enol Ether Synthesis2.4 Difluorinated Enol Ether Synthesis3 Applications3.1 Spiroketal Synthesis3.2 Spirocompound Synthesis3.3 Pseudodisaccharide Synthesis3.4 Total Synthesis of Jaspine B4 Modified Julia Olefination on Other Carboxylic Acid Derivatives4.1 Lactam Olefination and Spiroaminal Synthesis4.2 Bicyclic Enamide Synthesis by Intramolecular Modified Julia Olefination on Imides4.3 Modified Julia Olefination on Anhydrides5 Conclusion
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2

Zhang, Meixia, Qiao Zhou, Can Du, Yong Ding y Peng Song. "Detailed theoretical investigation on ESIPT process of pigment yellow 101". RSC Advances 6, n.º 64 (2016): 59389–94. http://dx.doi.org/10.1039/c6ra11140h.

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The ESIPT scheme amongenol–enol,enol–ketoandketo–keto: The equilibrium ESIPT process exists in the S1state. And following with the radiative transition, the reversed GSIPT can also occur in the S0state.
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3

Okano, Kentaro, Ryo Nakura, Kazuki Inoue y Atsunori Mori. "Practical Synthesis of Precursors of Cyclohexyne and 1,2-Cyclohexadiene". Synthesis 51, n.º 07 (11 de enero de 2019): 1561–64. http://dx.doi.org/10.1055/s-0037-1610356.

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This study investigated a practical method for regiocontrolled synthesis of precursors of strained cyclohexynes and 1,2-cyclohexadienes, which is a one-pot procedure consisting of a rearrangement of silyl enol ether and subsequent formation of the enol triflates. Triethylsilyl enol ether, derived from cyclohexanone, was treated with a combination of LDA and t-BuOK in n-hexane/THF to encourage the migration of the silyl group to generate an α-silyl enolate. Subsequently, the α-silyl enolate was reacted with Comins’ reagent to yield the corresponding enol triflate. Finally, the α-silylated trisubstituted lithium enolate for the synthesis of 1,2-cyclohexadiene precursor was isomerized in the presence of a stoichiometric amount of water for one hour at room temperature to exclusively provide tetrasubstituted lithium enolate for the synthesis of cyclohexyne precursor in one pot.
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4

Saculsan, Phoebe Grace J. y Akihisa Mori. "What Can the Philippines Learn from Thailand`s ENCON Fund in Overcoming the Barriers to Developing Renewable Energy Resources". Journal of Clean Energy Technologies 6, n.º 4 (julio de 2018): 278–83. http://dx.doi.org/10.18178/jocet.2018.6.4.474.

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5

Yang, Jinghui y Yan Xia. "Mechanochemical generation of acid-degradable poly(enol ether)s". Chemical Science 12, n.º 12 (2021): 4389–94. http://dx.doi.org/10.1039/d1sc00001b.

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6

Deng, Wei, Jiannan Xiang, Niannian Yi, Yi Xiong, De Chen, Sheng Zeng, Chaozhihui Cheng y Pengjie Wang. "Synthesis of β-CF3 Ketones through Copper/Silver Cocatalyzed Oxidative Coupling of Enol Acetates with ICH2CF3". Synlett 29, n.º 17 (22 de agosto de 2018): 2279–82. http://dx.doi.org/10.1055/s-0037-1610257.

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A simple method for the synthesis of β-CF3 ketones through copper/silver cocatalyzed oxidative coupling of enol acetates with ICH2CF3 has been developed. Enol acetates were chosen as the source of carbonyl group, giving the β-CF3 ketones in moderate yields. Control experiments imply that a radical process maybe involved in this reaction.
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7

Kumar, Manjeet. "Enol Acetates". Synlett 2011, n.º 15 (12 de agosto de 2011): 2272–73. http://dx.doi.org/10.1055/s-0030-1261159.

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8

Yang, Jinghui y Yan Xia. "Correction: Mechanochemical generation of acid-degradable poly(enol ether)s". Chemical Science 12, n.º 13 (2021): 4986. http://dx.doi.org/10.1039/d1sc90053f.

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9

Lanari, Daniela, Chiara Morozzi, Ornelio Rosati y Massimo Curini. "A Solvent-Free Reaction for Silyl Enol Ethers Synthesis". Synlett 29, n.º 01 (22 de agosto de 2017): 126–30. http://dx.doi.org/10.1055/s-0036-1590876.

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Silyl enol ethers are extremely useful nucleophilic intermediates for chemical transformations because they are synthetically versatile substrates for a wide range of C–C bond-forming reactions. Here, we present a new, mild, and solvent-free procedure for the synthesis of silyl enol ethers that employs a catalytic amount of solid-supported base and an equimolar amount of N,O-(bistrimethylsilyl)acetamide as a silylating agent.
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10

Fan, Ying-Ju, Jian-Ping Ma y Zhong-Xi Sun. "Bis{(E)-1-[1-(2-pyridyl)ethylidene]thiosemicarbazonato-κ3 N,N′,S}gallium(III) nitrate". Acta Crystallographica Section E Structure Reports Online 63, n.º 11 (5 de octubre de 2007): m2663. http://dx.doi.org/10.1107/s160053680704799x.

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Reaction of gallium(III) nitrate with (E)-1-[1-(2-pyridyl)ethylidene]thiosemicarbazide (petc) afforded the title complex, [Ga(C8H9N4S)2]NO3. The title complex contains one GaIII cation and two enol-form petc anions, accompanied by one charge-balancing disordered nitrate anion. The petc is in the enol form, coordinating to the GaIII centre via one S atom and two N atoms. Thus, the GaIII centre assumes a distorted octahedral coordination geometry.
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11

Leonov, Artem, Daria Timofeeva, Armin Ofial y Herbert Mayr. "Metal Enolates – Enamines – Enol Ethers: How Do Enolate Equivalents Differ in Nucleophilic Reactivity?" Synthesis 51, n.º 05 (8 de enero de 2019): 1157–70. http://dx.doi.org/10.1055/s-0037-1611634.

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The kinetics of the reactions of trimethylsilyl enol ethers and enamines (derived from deoxybenzoin, indane-1-one, and α-tetralone) with reference electrophiles (p-quinone methides, benzhydrylium and indolylbenzylium ions) were measured by conventional and stopped-flow photometry in acetonitrile at 20 °C. The resulting second-order rate constants were subjected to a least-squares minimization based on the correlation equation lg k = s N(N + E) for determining the reactivity descriptors N and s N of the silyl enol ethers and enamines. The relative reactivities of structurally analogous silyl enol ethers, enamines, and enolate anions towards carbon-centered electrophiles are determined as 1, 107, and 1014, respectively. A survey of synthetic applications of enolate ions and their synthetic equivalents shows that their behavior can be properly described by their nucleophilicity parameters, which therefore can be used for designing novel synthetic transformations.
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12

Aitken, Harry R. M., Margaret A. Brimble y Daniel P. Furkert. "A Catalytic Asymmetric Ene Reaction for Direct Preparation of α-Hydroxy 1,4-Diketones as Intermediates in Natural Product Synthesis". Synlett 31, n.º 07 (19 de febrero de 2020): 687–90. http://dx.doi.org/10.1055/s-0037-1610748.

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Asymmetric access to α-hydroxy-1,4-diketones has been achieved by direct ene coupling of silyl enol ethers with glyoxal electrophiles, mediated by a chiral N,N′-dioxide–nickel(II) complex catalyst. Successful union of a polyketide silyl enol ether with an α-quaternary glyoxal, generated by dioxirane oxidation of an α-diazo ketone, models a proposed C5–C6 disconnection of the polyketide and spirocyclic imine domains of the marine natural product, portimine.
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13

Arkhipov, Sergey G., Peter S. Sherin, Alexey S. Kiryutin, Vladimir A. Lazarenko y Christian Tantardini. "The role of S-bond in tenoxicam keto–enolic tautomerization". CrystEngComm 21, n.º 36 (2019): 5392–401. http://dx.doi.org/10.1039/c9ce00874h.

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A non-covalent interaction between the sulphur atom of thiophenyl moiety and oxygen of the carbonyl group (S-bond) plays a crucial role in keto–enol tautomerization of tenoxicam leading to the crystallization of latter only in zwitterionic (ZWC) and not in β-keto–enolic (BKE) form.
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14

Muhl, Jennifer R., Lisa I. Pilkington y Rebecca C. Deed. "New Precursors to 3-Sulfanylhexan-1-ol? Investigating the Keto–Enol Tautomerism of 3-S-Glutathionylhexanal". Molecules 26, n.º 14 (14 de julio de 2021): 4261. http://dx.doi.org/10.3390/molecules26144261.

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The volatile thiol compound 3-sulfanylhexan-1-ol (3SH) is a key impact odorant of white wines such as Sauvignon Blanc. 3SH is produced during fermentation by metabolism of non-volatile precursors such as 3-S-gluthathionylhexanal (glut-3SH-al). The biogenesis of 3SH is not fully understood, and the role of glut-3SH-al in this pathway is yet to be elucidated. The aldehyde functional group of glut-3SH-al is known to make this compound more reactive than other precursors to 3SH, and we are reporting for the first time that glut-3SH-al can exist in both keto and enol forms in aqueous solutions. At wine typical pH (~3.5), glut-3SH-al exists predominantly as the enol form. The dominance of the enol form over the keto form has implications in terms of potential consumption/conversion of glut-3SH-al by previously unidentified pathways. Therefore, this work will aid in the further elucidation of the role of glut-3SH-al towards 3SH formation in wine, with significant implications for the study and analysis of analogous compounds.
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15

Willis, Michael C., Gareth N. Brace y Ian P. Holmes. "Efficient Palladium-Catalysed Enamide Synthesis from Enol Triflates and Enol Tosylates". Synthesis, n.º 19 (2005): 3229–34. http://dx.doi.org/10.1055/s-2005-918480.

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16

Braga, Antonio L., Claudio C. Silveira, Luciano Dornelles, Gilson Zeni, Flavia A. D. Galarza y Ludger A. Wessjohann. "Catalyst-Dependent Selective Synthesis of O/S- and S/S-Acetals from Enol Ethers". Synthetic Communications 25, n.º 20 (octubre de 1995): 3155–62. http://dx.doi.org/10.1080/00397919508015466.

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17

Sarkar, Sujit, Namita Devi, Bikoshita Porashar, Santu Ruidas y Anil Saikia. "Stereoselective Synthesis of 4-O-Tosyltetrahydropyrans via Prins Cyclization Reaction of Enol Ethers". SynOpen 03, n.º 01 (enero de 2019): 36–45. http://dx.doi.org/10.1055/s-0037-1611679.

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18

Suresh, J., R. Suresh Kumar, S. Perumal y S. Natarajan. "(2RS,5SR,6SR)-Ethyl 2,6-bis(4-fluorophenyl)-4-hydroxy-5-phenylsulfanyl-1,2,5,6-tetrahydropyridine-3-carboxylate". Acta Crystallographica Section E Structure Reports Online 63, n.º 3 (21 de febrero de 2007): o1377—o1379. http://dx.doi.org/10.1107/s1600536807007179.

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The title compound, C26H23F2NO3S, a polysubstituted piperidine enol, adopts a twisted half-chair conformation. The crystal structure is stabilized by N—H...F, C—H...O and weak C—H...π interactions. An intramolecular O—H...S interaction generates an S(5) graph-set motif.
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19

Renaud, Philippe, Monica Gonçalves-Martin y Andreas Saxer. "A Practical Synthesis of (S)-Cyclopent-2-enol". Synlett 2009, n.º 17 (24 de septiembre de 2009): 2801–2. http://dx.doi.org/10.1055/s-0029-1217983.

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20

Renaud, Philippe, Monica Gonçalves-Martin y Andreas Saxer. "A Practical Synthesis of (S)-Cyclopent-2-enol". Synlett 2010, n.º 05 (marzo de 2010): 840. http://dx.doi.org/10.1055/s-0029-1219555.

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21

Kraus, George A. y Shuai Wang. "The Dianion of Dehydroacetic Acid: A Direct Synthesis of Pogopyrone A". Synthesis 52, n.º 10 (12 de febrero de 2020): 1541–43. http://dx.doi.org/10.1055/s-0037-1610752.

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Dehydroacetic acid was converted into a silyl enol ether and titanium enolate. These reacted effectively with aldehydes and N-bromosuccinimide. Oxidation of the adduct with benzaldehyde afforded pogopyrone A in excellent overall yield.
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22

Yu, Jin-Sheng, Jian Zhou, Xiao-Si Hu, Yi Du, Fu-Min Liao y Pei-Gang Ding. "A Highly Efficient Gold(I)-Catalyzed Mukaiyama–Mannich Reaction of α-Amino Sulfones with Fluorinated Silyl Enol Ethers To Give β-Amino α-Fluorinated Ketones". Synlett 28, n.º 16 (12 de julio de 2017): 2194–98. http://dx.doi.org/10.1055/s-0036-1588475.

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Ph3PAuOTf was identified as a powerful catalyst for the ­Mukaiyama–Mannich reaction of fluorinated silyl enol ethers with α-amino sulfones. This provides ready access to β-amino α-fluorinated ketones in good to excellent yields.
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23

Yanagisawa, Akira, Kazuaki Ishihara y Hisashi Yamamoto. "Asymmetric Protonations of Enol Derivatives". Synlett 1997, Sup. I (junio de 1997): 411–20. http://dx.doi.org/10.1055/s-1997-6131.

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24

Kotyatkina, Anna I., Vladimir N. Zhabinskii, Vladimir A. Khripach y Aede de Groot. "Synthesis of 8,14-Secosteroids from (S)-(+)-Carvone". Collection of Czechoslovak Chemical Communications 65, n.º 7 (2000): 1173–82. http://dx.doi.org/10.1135/cccc20001173.

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A total synthesis of functionalised 8,14-seco steroids with five- and six-membered D rings is described. The synthesis is based on the transformation of (S)-carvone into a steroidal AB ring moiety with a side chain at C-9 that allowed the creation of a nitrile oxide at this position. The nitrile oxides were coupled with cyclic enones or enol derivatives of 1,3-diketones, and reductive cleavage of the obtained cycloadducts gave the desired products. The formation of a twelve-membered ring compound was observed in cycloaddition of one of the nitrile oxides with cyclopentenone as the result of an intramolecular ene-reaction followed by retroaldol reaction.
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25

LI, QIANG-GEN, YING XUE, YI REN, NING-BEW WONG y WAI-KEE LI. "AB INITIO COMPUTATIONAL INVESTIGATIONS ON THE GAS-PHASE HOMODIMERIZATION AND KETO-ENOL TAUTOMERISM OF THE MONOCHALCOGENOCARBOXYLIC ACIDS CH3C(=O)XH (X = S, Se, Te)". Journal of Theoretical and Computational Chemistry 10, n.º 01 (febrero de 2011): 41–51. http://dx.doi.org/10.1142/s021963361100627x.

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Computational investigations on the gas-phase homodimerization and the keto-to-enol tautomerism of monochalcogenocarboxylic acids, CH3C(=O)XH (X = S, Se, Te) , were performed using ab initio molecular orbital methods (HF and MP2) with the 6-311+G(d, p) and 6-311+G(2df, 2df) basis sets. Calculated results indicate that the dimerization enthalpy values, ΔH, for the enol-dimers, [CH3C(=X)OH]2 (X = S, Se, Te) , are notably higher than those for the corresponding keto-dimers, [CH3C(=O)XH]2 (X = S, Se, Te) , while the ΔH values decrease as the electronegativity of chalcogen atom is lowered, for both the keto- and enol-dimers. It is found that the homodimerization of monochalcogenocarboxylic acids is thermodynamically unfavorable because the releasing dimerization heat cannot overcome the loss of entropy. This is contrasted with the case in the carboxylic acid, where the much higher dimerization enthalpy is responsible for the favorable dimerization in the gas phase. Our results also suggest that the tautomeric reactions of the monochalcogenocarboxylic acids in the gas phase may proceed by an eight-membered ring TS with intermolecular double proton transfer and lower tautomeric barrier, instead of by direct intramolecular proton transfer in monomer with a highly strained four-membered TS. The geometrical and energetic characteristics of the homodimers and tautomeric TSs are also further elucidated by NBO analysis.
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26

Pettus, Thomas, Zhen-Gao Feng y G. Burnett. "A Biomimetic Synthesis of des-Hydroxy Paecilospirone". Synlett 29, n.º 11 (9 de mayo de 2018): 1517–19. http://dx.doi.org/10.1055/s-0036-1592001.

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The carbon framework of des-hydroxy paecilospirone was rapidly synthesized using a biomimetic approach whereby an enol ether and an ortho-quinone methide (o-QM), each derived from the same lactone, were combined to arrive at the complete carbon skeleton of paecilospirone.
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27

BRAGA, A. L., C. C. SILVEIRA, L. DORNELLES, G. ZENI, F. A. D. GALARZA y L. A. WESSJOHANN. "ChemInform Abstract: Catalyst-Dependent Selective Synthesis of O/S- and S/S-Acetals from Enol Ethers." ChemInform 26, n.º 51 (16 de agosto de 2010): no. http://dx.doi.org/10.1002/chin.199551079.

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28

Yanagisawa, Akira, Kenichi Asakawa y Hisashi Yamamoto. "Asymmetric aldol reaction of enol trichloroacetate catalyzed by (S,S)-(EBTHI)TiCl(OMe)". Chirality 12, n.º 5-6 (2000): 421–24. http://dx.doi.org/10.1002/(sici)1520-636x(2000)12:5/6<421::aid-chir22>3.0.co;2-t.

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29

Li, Jun, Shaoyu An, Chao Yuan y Pingfan Li. "Enantioselective Protonation of Silyl Enol Ethers Catalyzed by a Chiral Pentacarboxycyclopentadiene-Based Brønsted Acid". Synlett 30, n.º 11 (29 de mayo de 2019): 1317–20. http://dx.doi.org/10.1055/s-0037-1611849.

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The enantioselective protonation of silyl enol ethers was realized in the presence of a pentacarboxycyclopenta-1,3-diene-based chiral Brønsted acid catalyst with water as an achiral proton source to give the corresponding α-aryl ketones in good yields and up to 75% ee.
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30

Tsuchimochi, Izuru, Yuta Kitamura, Hiroshi Aoyama, Shuji Akai, Keiyo Nakai y Takehiko Yoshimitsu. "Total synthesis of (−)-agelastatin A: an SH2′ radical azidation strategy". Chemical Communications 54, n.º 71 (2018): 9893–96. http://dx.doi.org/10.1039/c8cc05697h.

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A new synthetic approach to (−)-agelastatin A has been established through the strategic implementation of brominative olefin transposition of a silyl enol ether and subsequent SH2′ radical azidation of the resultant allylic bromide.
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31

Kocienski, Philip J. y Jacqueline E. Milne. "A Synthesis of α-Lithiated Enol Ethers from α-Arenesulfinyl Enol Ethers: Ni(0)- and Pd(0)-Catalysed Coupling of Enol Triflates and Phosphates Derived from Lactones with Sodium Arenethiolates Gives α-Arenesulfanyl Enol Ethers". Synthesis 2003, n.º 04 (2003): 0584–92. http://dx.doi.org/10.1055/s-2003-37661.

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32

Takeda, Takeshi, Kensaku Sato y Akira Tsubouchi. "A New Route to Enol Ethers". Synthesis 2004, n.º 09 (2004): 1457–65. http://dx.doi.org/10.1055/s-2004-822367.

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33

Barba, Fructuoso, M. Gloria Quintanilla y Guillermo Montero. "Regioselective Electrochemical Synthesis of Enol Carbonates". Synthesis 1992, n.º 12 (1992): 1215–16. http://dx.doi.org/10.1055/s-1992-26339.

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34

Takeda, T., A. Tsubouchi, S. Enatsu y R. Kanno. "Regio- and Stereoselective Silyl Enol Ethers". Synfacts 2011, n.º 01 (21 de diciembre de 2010): 0088. http://dx.doi.org/10.1055/s-0030-1259120.

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35

Zhang, Xiao-Ru, Su-Lan Zhou, Yi Yuan, Wei Du y Ying-Chun Chen. "Chemo- and Regioselective Asymmetric Friedel–Crafts Reaction of Furans and Thiophenes with α,β-Unsaturated Aldehydes through Dual Activation". Synlett 28, n.º 14 (10 de mayo de 2017): 1771–74. http://dx.doi.org/10.1055/s-0036-1588831.

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A highly chemo- and regioselective Friedel–Crafts alkylation reaction of furans and thiophenes has been developed, which relies on the activation from the remote conjugated Mukaiyama silyl enol ether motif. Excellent enantioslectivity is generally obtained in reactions with α,β-unsaturated aldehydes under the well-established iminium ion catalysis of a chiral secondary amine.
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36

Netto-Ferreira, J. C. y J. C. Scaiano. "Laser flash photolysis study of the photochemistry of ortho-benzoylbenzaldehyde". Canadian Journal of Chemistry 71, n.º 8 (1 de agosto de 1993): 1209–15. http://dx.doi.org/10.1139/v93-156.

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Ketene-enols 4 and 5 have been generated by laser flash photolysis of ortho-benzoylbenzaldehyde (3) and kinetically and spectroscopically characterized. In benzene or acetonitrile, the E ketene-enol, 4, shows absorption at 340 and 400 nm and a lifetime in excess of 1 ms, whereas the Z ketene-enol, 5, shows maxima at 360 and 430 nm and a lifetime of only 1.5 μs. At shorter time scales we observed a weak absorption (λmax = 580 nm) tentatively assigned to biradical 6 with a lifetime of 140 ns. The E ketene-enol is readily quenched by oxygen, dienophiles, methanol, and water, with quenching rate constants ranging from 3.6 × 103 M−1 s−1 (for methanol as a quencher) to 2.2 × 108 M−1 s−1 (for diethylketomalonate). At high water concentrations (typically > 10 M) a new species, 7, was detected showing maximum absoiption at 510 nm and a growth lifetime of 7 μs. In deuterated water and using the same concentration as before we observed a formation lifetime for 7 of 10 μs, which results in an isotope effect of ~ 1.5. It is proposed that 5 is the main precursor for 7. Steady-state irradiation of 3 in deaerated methanol leads to the formation of dihydroanthraquinone (9), a strongly colored and fluorescent (λmax = 475 nm, τn = 29 ns) species, whereas 3-phenylphthalide (2, R = Ph) is the main product when the irradiation is performed in benzene. Steady-state quenching of product formation by diethyl ketomalonate gives a Stern–Volmer constant of 380 M−1 from which we conclude that 5 is the ketene-enol responsible for product formation, in agreement with the laser flash photolysis results.
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37

Lin, Qi, Tao-Tao Lu, Jin-Chao Lou, Gui-Yuan Wu, Tai-Bao Wei y You-Ming Zhang. "A “keto–enol tautomerization”-based response mechanism: a novel approach to stimuli-responsive supramolecular gel". Chemical Communications 51, n.º 61 (2015): 12224–27. http://dx.doi.org/10.1039/c5cc04089b.

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By “keto–enol tautomerization”, gelator G3 can be self-assembled into a stable organogel (OG3) accompanied by strong aggregation induced emission (AIE). OG3 could dual-channel sense S2− with specific selectivity via reversible sol–gel transition and fluorescent changes.
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38

Hu, Gao-Bo, Da-Wei Jiang, Jiang-Yan Li, Yan Rao y Li-Yuan Jiang. "Crystal structure of (5′S,8′S)-3-(2,5-dimethylphenyl)-8-methoxy-3-nitro-1-azaspiro[4.5]decane-2,4-dione". Acta Crystallographica Section E Crystallographic Communications 71, n.º 4 (14 de marzo de 2015): o238—o239. http://dx.doi.org/10.1107/s2056989015004715.

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The title compound, C18H22N2O5, was synthesized by nitrification of its enol precursor. The pyrrolidine ring plane adopts a twisted conformation about the C—C bond linking the spiro centre and the C=O group remote from the N atom. It makes dihedral angles of 71.69 (9) and 88.92 (9)°, respectively, with the benzene ring plane and the plane defined by the four C atoms that form the seat of the of the cyclohexane chair. At the spiro centre, the NH group is axial and the C=O group is equatorial with respect to the cyclohexane ring. In the crystal, inversion dimers linked by pairs of N—H...O hydrogen bonds generateR22(8) loops. The dimers are linked by C—H...O interactions, generating a three-dimensional network.
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39

Suresh, J., R. Suresh Kumar, S. Perumal y S. Natarajan. "(2RS,5RS,6RS)-Ethyl 4-hydroxy-2,6-di-p-tolyl-5-p-tolylsulfanyl-1,2,5,6-tetrahydropyridine-3-carboxylate". Acta Crystallographica Section E Structure Reports Online 63, n.º 3 (21 de febrero de 2007): o1375—o1376. http://dx.doi.org/10.1107/s1600536807007167.

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The polysubstituted piperidine enol ring in the title compound, C29H31NO3S, adopts a twisted half-chair conformation. The crystal structure is stabilized by van der Waals and weak C—H...π interactions. An intramolecular O—H...O interaction generates an S(6) graph-set motif.
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40

Yokoshima, Satoshi, Shinya Watanabe, Masatsugu Ishikawa, Toshimune Nomura y Tohru Fukuyama. "Total Synthesis of Lycoposerramine-R". Synlett 29, n.º 18 (16 de octubre de 2018): 2377–80. http://dx.doi.org/10.1055/s-0037-1611024.

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A total synthesis of lycoposerramine-R was accomplished. The synthesis featured a Claisen–Ireland rearrangement to install a two-carbon unit, and a hetero-Diels–Alder reaction to form a cyclic enol ether that reacted with an ethynyl group to construct a cis-hydrindane core containing a quaternary carbon. A 2-pyridone synthesis using 2-(phenylsulfinyl)acetamide was used to complete the synthesis.
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41

El-Amri, Aeshah, Shaaban A. Elroby, Oliver Kühn y Rifaat H. Hilal. "Toward understanding tautomeric switching in 4-hydroxynaphthaldehyde and its dimers: A DFT and quantum topology study". Journal of Theoretical and Computational Chemistry 14, n.º 03 (mayo de 2015): 1550016. http://dx.doi.org/10.1142/s0219633615500169.

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The electronic structures and stabilities of all benzenoid (enol) and quinonoid (keto) forms of 4-hydroxynaphthaldehyde (ALD-14) have been investigated using density functional theory (DFT) with a range of functionals and basis sets. The anti-enol form represents the global minimum energy structure. Low rotation barriers of both the hydroxyl and the aldehyde groups characterize this form. Fourier analysis of the potential energy function for rotation indicate that the conformational preference of ALD-14 is determined by both the dipole–dipole repulsion and bond moments interactions. Further, three different ALD-14 dimer complexes are investigated, i.e. head-to-tail (HT), head-to-head (HH), and stacked (S) forms. The analysis of natural bond order, quantum topology features of the Laplacian of the electron density, binding energies and structural parameters of these dimers point to comparable stabilities of the HT and S-dimers, with a preference for a stacking contact. The origin of its stability can be traced to π-conjugative, H-bonding and dispersion interactions.
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42

Fan, Ying-Ju, Le Wang, Jian-Ping Ma y Zhong-Xi Sun. "Dichloro(ethanol-κO){(E)-1-[1-(2-pyridyl)ethylidene]thiosemicarbazonato-κ3 N,N′,S}indium(III)". Acta Crystallographica Section E Structure Reports Online 63, n.º 3 (23 de febrero de 2007): m845—m846. http://dx.doi.org/10.1107/s1600536807006290.

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Reaction of indium(III) chloride with (E)-1-[1-(2-pyridyl)ethylidene]thiosemicarbazide afforded the title complex, [In(C8H9N4S)Cl2(C2H5OH)]. The ligand is in the enol form coordinating to the InIII atom through one S atom and two N atoms. The InIII atom is further coordinated by two Cl atoms and an ethanol molecule to complete a distorted octahedral coordination geometry.
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43

Shi, Y., H. Du y J. Long. "Simmons-Smith Cyclopropanation of Silyl Enol Ethers". Synfacts 2006, n.º 9 (septiembre de 2006): 0920. http://dx.doi.org/10.1055/s-2006-949245.

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44

Lautens, Mark y Matthew L. Maddess. "Preparation and Utility of Cyclic Enol Carbonates". Synthesis 2004, n.º 09 (2004): 1399–408. http://dx.doi.org/10.1055/s-2004-822401.

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45

Pfaendler, Hans Rudolf y Franz Xaver Müller. "A Simple Preparation of Enol Ether Lipids". Synthesis 1992, n.º 04 (1992): 350–52. http://dx.doi.org/10.1055/s-1992-26104.

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46

List, Benjamin, Grigory Shevchenko y Gabriele Pupo. "Direct Asymmetric α-Hydroxylation of Cyclic α-Branched Ketones through Enol Catalysis". Synlett 30, n.º 01 (14 de noviembre de 2018): 49–53. http://dx.doi.org/10.1055/s-0037-1611084.

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Enantiopure α-hydroxy carbonyl compounds are common scaffolds in natural products and pharmaceuticals. Although indirect approaches towards their synthesis are known, direct asymmetric methodologies are scarce. Herein, we report the first direct asymmetric α-hydroxylation of α-branched ketones through enol catalysis, enabling a facile access to valuable α-keto tertiary alcohols. The transformation, characterized by the use of nitrosobenzene as the oxidant and a new chiral phosphoric acid as the catalyst, delivers a good scope and excellent enantioselectivities.
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47

Temel, Ersin, Çiğdem Albayrak, Mustafa Odabaşoğlu y Orhan Büyükgüngör. "(E)-3-[(2-Bromophenyl)iminomethyl]benzene-1,2-diol". Acta Crystallographica Section E Structure Reports Online 63, n.º 3 (14 de febrero de 2007): o1319—o1320. http://dx.doi.org/10.1107/s1600536807006046.

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The title compound, C13H10BrNO2, crystallizes in an enol–imine form. The molecule is roughly planar, with a dihedral angle of 5.13 (10)° between the aromatic rings. Intramolecular O—H...N hydrogen bonding generates an S(6) ring motif, whereas intermolecular O—H...O hydrogen bonding links the molecules into centrosymmetric R 2 2(10) dimers.
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48

Zhou, Zhe y László Kürti. "Electrophilic Amination: An Update". Synlett 30, n.º 13 (8 de julio de 2019): 1525–35. http://dx.doi.org/10.1055/s-0037-1611861.

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In this account, we provide an overview of some recent advances in electrophilic amination methodologies that have been developed in the Kürti group over the last seven years. Our group’s focus has been to develop novel amination methodologies that directly yield N-unprotected amine products.1 Introduction2 Amination of Boronic Acids3 Aziridination of Unactivated Olefins4 Rhodium-Catalyzed C–H Amination of Arenes5 Synthesis of Carbazoles6 Amination of Aryl- and Alkylmetals7 Doubly Electrophilic N-Linchpin Reagents8 Aza-Rubottom Oxidation of Silyl Enol Ethers9 Summary
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49

Hioki, Yuto, Mayu Itoh, Atsunori Mori y Kentaro Okano. "One-Pot Deprotonative Synthesis of Biarylazacyclooctynones". Synlett 31, n.º 02 (4 de diciembre de 2019): 189–93. http://dx.doi.org/10.1055/s-0039-1691491.

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Deprotonative formation of biarylazacyclooctynone (BARAC) from the corresponding enol triflate is described. The reaction furnished the azacyclooctynone within one hour at –78 °C. This process could be performed in one pot from the starting ketone to provide a range of BARAC derivatives in moderate to excellent yields. The protocol enabled the gram-scale formation of the BARAC skeleton by reducing the number of reaction steps. Furthermore, the established method was applied to the synthesis of the BARAC derivative bearing a coumarin moiety.
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50

Verkade, J., J. Hartwig, W. Su, S. Raders y X. Liao. "Pd-Catalyzed α-Arylation of Trimethylsilyl Enol Ethers". Synfacts 2006, n.º 11 (noviembre de 2006): 1164. http://dx.doi.org/10.1055/s-2006-949478.

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