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Artykuły w czasopismach na temat „Ketenes”

Autor: Grafiati

Data publikacji: 4 czerwca 2021

Data aktualizacji: 31 lipca 2024

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1

Ríos-Gutiérrez, Mar, Andrea Darù, Tomás Tejero, Luis R. Domingo i Pedro Merino. "A molecular electron density theory study of the [3 + 2] cycloaddition reaction of nitrones with ketenes". Organic & Biomolecular Chemistry 15, nr 7 (2017): 1618–27. http://dx.doi.org/10.1039/c6ob02768g.

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The zw-type 32CA reactions of nitrones with ketenes are controlled by the nucleophilic character of the nitrone and the electrophilic character of the ketene. They are chemo- and regio-selective and the use of electrophilic ketenes changes the mechanism from one-step to two-step.

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2

Andraos, J., Y. Chiang, S. J. Eustace, A. J. Kresge, S. W. Paine, V. V. Popik i K. Sung. "Article". Canadian Journal of Chemistry 77, nr 4 (1.04.1999): 459–62. http://dx.doi.org/10.1139/v99-058.

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Five ketenes, phenyl(ethyl)ketene, phenyl(methylthio)ketene, diphenylketene, pentafluorophenylketene, and 1-naphthylketene, were generated flash photolytically and solvent isotope effects (H2O vs. D2O) on their hydroxide-ion-catalyzed hydration in aqueous solution were determined. The values obtained are all weakly inverse and closely similar (kHO/kDO = 0.76-0.97), as expected for these fast, hydroxide-ion-consuming reactions, known to proceed by nucleophilic attack of hydroxide on the ketene carbonyl group. The characteristic magnitude of these isotope effects should prove useful in identifying new examples of this reaction.Key words: ketenes, flash photolysis, photo-Wolff reaction, solvent isotope effects on hydroxide ion consumption.

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3

Ahmed, Issahaku, Richard Tia i Evans Adei. "A density functional theory study of the mechanisms of addition of transition metal oxides ReO3L(L = Cl-, O-, OCH3, CH3) to substituted ketenes". Journal of Theoretical and Computational Chemistry 14, nr 05 (sierpień 2015): 1550035. http://dx.doi.org/10.1142/s0219633615500352.

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Ketenes are excellent precursors for catalytic asymmetric reactions, creating chiral centers mainly through addition across their C = C bonds. Density functional theory (DFT) calculations at the MO6/LACVP* and B3LYP/LACVP* levels of theory were employed in a systematic investigation of the peri-, chemo- and regio-selectivity of the addition of transition metal oxo complexes of the type ReO 3 L ( L = Cl -, O -, OCH 3, CH 3) to substituted ketenes O = C = C ( CH 3)(X) [ X = CH 3, H , CN , Ph ] with the aim of elucidating the effects of substituents on the mechanism of the reactions. The [2 + 2] addition pathway across the C = C or C = O (depending on the ligand) is the most preferred in the reactions of dimethyl ketene with all the metal complexes studied. The [2 + 2] pathway is also the most preferred in the reactions of ReO 3 Cl with all the substituted ketenes studied except when X = Cl . Thus of all the reactions studied, it is only the reaction of ReO 3 Cl with O = C = C ( CH 3)( Cl ) that prefers the [3 + 2] addition pathway. Reactions of dimethyl ketene with ReO 3 L favors addition across C = O bonds of the ketene when L = O - and CH 3 but favors addition across C = C bonds when L = OCH 3 and Cl . In the reactions of ReO 3 Cl with substituted ketenes, addition across C = O bonds is favored only when X = H while addition across C = C bonds is favored when X = CH 3, Cl , Ph , CN . The reactions of dimethyl ketene with ReO 3 L will most likely lead to the formation of an ester precursor in each case. A zwitterionic intermediate is formed in the reactions except in the reactions of [Formula: see text]. The order in the activation energies of the reactions of dimethyl ketenes with the metal complexes ReO 3 L with respect to changing ligand L is O - < CH 3 O - < Cl - < CH 3 while the order in reaction energies is CH 3 < CH 3 O - < O - < Cl -. For the reactions of substituted ketenes with ReO 3 Cl , the order in activation barriers is CH 3 < Ph < CN < Cl < H while the reaction energies follow the order Cl < CH 3 < H < Ph < CN . In the reactions of dimethyl ketenes with ReO 3 L , the trend in the selectivity of the reactions with respect to ligand L is Cl - < CH 3 O - < CH 3 < O - while the trend in selectivity is CH 3 < CN < Cl < Ph in the reactions of ReO 3 Cl with substituted ketenes. It is seen that reactions involving a change in oxidation state of metal from the reactant to product have high activation barriers while reactions that do not involve a change in oxidation state have low activation barriers. For both [3 + 2] and [2 + 2] additions, low activation barriers are obtained when the substituent on the ketene is electron-donating while high activation barriers are obtained when the substituent is electron-withdrawing.

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4

Lystsova, Ekaterina A., Ekaterina E. Khramtsova i Andrey N. Maslivets. "Acyl(imidoyl)ketenes: Reactive Bidentate Oxa/Aza-Dienes for Organic Synthesis". Symmetry 13, nr 8 (17.08.2021): 1509. http://dx.doi.org/10.3390/sym13081509.

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Polyfunctional building blocks are essential for the implementation of diversity-oriented synthetic strategies, highly demanded in small molecule libraries’ design for modern drug discovery. Acyl(imidoyl)ketenes are highly reactive organic compounds, bearing both oxa- and aza-diene moieties, conjugated symmetrically to the ketene fragment, enabling synthesis of various skeletally diverse heterocycles on their basis. The highlights of reactions utilizing acyl(imidoyl)ketenes are high yields, short reaction time (about several minutes), high selectivity, atom economy, and simple purification procedures, which benefits the drug discovery. The present review focuses on the approaches to thermal generation of acyl(imidoyl)ketenes, patterns of their immediate transformations via intra- and intermolecular reactions, including the reactions of cyclodimerization, in which either symmetric or dissymmetric heterocycles can be formed. Recent advances in investigations on mechanisms, identifications of intermediates, and chemo- and regioselectivity of reactions with participation of acyl(imidoyl)ketenes are also covered.

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5

Allen, Annette D., A. Jerry Kresge, Norman P. Schepp i Thomas T. Tidwell. "Hydration reactivity of ketenes generated by flash photolysis". Canadian Journal of Chemistry 65, nr 8 (1.08.1987): 1719–23. http://dx.doi.org/10.1139/v87-287.

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The ketenes n-BuCH=C=O, PhCH=C=O, and Ph2C=C=O have been generated by flash photolysis and their reactivities toward water, including acid and base catalysis, have been measured in wholly aqueous media by ultraviolet spectrophotometry. The phenyl group electronically enhances the reactivity of ketenes relative to n-butyl toward water and hydroxide, but retards reaction with protic acids. The presence of bulky groups, including phenyls, on each side in the ketene plane sterically retards nucleophilic attack. The reactions are interpreted as involving in-plane attack by nucleophilic water or hydroxide in the neutral and base-induced reactions, and electrophilic protonation perpendicular to the ketene plane for the acid-catalyzed reaction.

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6

Brook, Adrian G., i Abraha Habtemariam. "Insertion reactions of nitrosobenzene and ketenes into silaaziridines". Canadian Journal of Chemistry 81, nr 11 (1.11.2003): 1164–67. http://dx.doi.org/10.1139/v03-001.

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Nitrosobenzene, trimethylsilyl ketene, and diphenylketene insert into the ring of silaaziridines to yield relatively unstable 5-membered heterocyclic ring systems. The new compounds, which have been characterized by 1H, 13C, and 29Si NMR spectroscopy, arise from two different modes of insertion into the ring SiN bond, leading to compounds with an exocyclic C=N bond (from nitrosobenzene) or two exocyclic C=C bonds (from the ketenes).Key words: silaaziridines, ring insertion, nitrosobenzene, ketenes, heterocyclic rings.

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7

Jörges, Mike, Felix Krischer i Viktoria H. Gessner. "Transition metal–free ketene formation from carbon monoxide through isolable ketenyl anions". Science 378, nr 6626 (23.12.2022): 1331–36. http://dx.doi.org/10.1126/science.ade4563.

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The capacity of transition metals to bind and transform carbon monoxide (CO) is critical to its use in many chemical processes as a sustainable, inexpensive C1 building block. By contrast, only few s- and p-block element compounds bind and activate CO, and conversion of CO into useful carbonyl-containing organic compounds in such cases remains elusive. We report that metalated phosphorus ylides provide facile access to ketenyl anions ([RC=C=O] – ) by phosphine displacement with CO. These anions are very stable and storable reagents with a distinctive electronic structure between that of the prototypical ketene (H 2 C=C=O) and that of ethynol (HC≡C–OH). Nonetheless, the ketenyl anions selectively react with a range of electrophiles at the carbon atom, thus offering high-yielding and versatile access to ketenes and related compounds.

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8

Andraos, John, i A. Jerry Kresge. "Correlation of rates of uncatalyzed and hydroxide-ion catalyzed ketene hydration. A mechanistic application and solvent isotope effects on the uncatalyzed reaction". Canadian Journal of Chemistry 78, nr 4 (1.04.2000): 508–15. http://dx.doi.org/10.1139/v00-032.

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Rates of hydration of a number of ketenes were measured in neutral and basic solution using flash photolytic techniques, and rate constants for their uncatalyzed, kuc, and hydroxide-ion catalyzed, kHO, reactions were determined. These results, plus additional data from the literature, were found to provide the remarkably good correlation log kuc = -3.21 + 1.14 log kHO, which spans 10 orders of magnitude in reactivity and includes 31 ketenes. This good correlation implies that uncatalyzed and hydroxide-ion catalyzed ketene hydraton occur by similar reaction mechanisms, which for the hydroxide-ion catalyzed process is known to involve nucleophilic attack on the carbonyl carbon atom of the ketene. Rate constants for phenylhydroxyketene, on the other hand, do not fit this correlation, which suggests that the mechanistic assignment upon which these rate constants are based may not be correct. Solvent isotope effects on these uncatalyzed ketene hydrations are weak; most are less than kH/kD = 2. It is argued that these isotope effects are largely, if not entirely, secondary in nature and that they are consistent with both a reaction mechanism in which nucleophlic attack of a single water molecule on the ketene carbonyl carbon atom produces a zwitterionic intermediate and also a mechanism that avoids this intermediate by passing through a cyclic transition state involving several water molecules.Key words: ketene hydration, rate correlation, nucleophilic attack, solvent isotope effects, phenylhydroxyketene.

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9

McAllister, Michael A., i Thomas T. Tidwell. "Structural and substituent effects on the ketene infrared stretching frequency". Canadian Journal of Chemistry 72, nr 3 (1.03.1994): 882–87. http://dx.doi.org/10.1139/v94-115.

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The frequencies and intensities of the ketene asymmetric stretching vibration near 2100 cm−1 for a series of substituted ketenes and fulvenones have been calculated using ab initio molecular orbital methods. Comparisons of the calculated values with experimentally determined results show reasonably good agreement in most cases, with a typical deviation of ± 10 cm−1 between the measured and calculated values. A test of a correlation proposed by Gano and Jacob (Spectrochim. Acta, 43A, 1023 (1987)) of the frequencies with substituent field and resonance parameters F and R shows a modest correlation coefficient of 0.86, with no significant dependence on R. These results are consistent with enhancements of ketene infrared absorption frequencies by interaction of substituents with the negative charge density at Cβ of ketenes, as indicated by the resonance structure [Formula: see text] The calculated intensities I (km/mol) for non-π acceptor substituents are correlated with the group electronegativities X by the relationship I = 1841.6 − 305.7X (r = 0.94). The π-acceptor substituents show exaltations of the intensities, and the results are interpreted as showing an enhancement of intensities by electropositive substituents increasing the normal ketene dipole directed towards oxygen, and an opposite effect by π-acceptor substituents delocalizing the negative charge at Cβ.

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10

Fu, Nanyan, Annette D. Allen, Winnie Chan, Shinjiro Kobayashi, Thomas T. Tidwell, Daryoush Tahmassebi, Angelica Aguilar, Eduardo Peña Cabrera i Jazmin Godoy. "Generation, observation, and reactivity of furyl- and thienylketenes and bisketenes". Canadian Journal of Chemistry 86, nr 4 (1.04.2008): 333–41. http://dx.doi.org/10.1139/v08-021.

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2- and 3-Furylketenes (18 and 20), 2- and 3-thienylketenes (19 and 21), and bis(2,5-ketenyl)thiophene (24) have been generated as observable reactive intermediates by photochemical Wolff rearrangements. Stabilization energies of the monoketenes 18–21 have been determined by DFT computations of isodesmic energy changes, and these ketenes are predicted to be modestly destabilized relative to phenylketene. Rate constants for reaction of 18–21 with H2O and with n-BuNH2 have been measured and are similar to those of the 2-, 3-, and 4-pyridylketenes (1). The product of reaction of 2-furylketene (18) with H2O is calculated to be stable as an acid enol, and reaction of 18 with the stable free radical TEMPO forms a stable ester enol, consistent with stabilization by intramolecular H-bonding to the furyl oxygen. Bis(thienyl)-1,2-bisketenes 26 and 28 have been generated by photochemical cyclobutenedione ring opening and are highly reactive in ring closure. This is attributed to destabilization of the ketenes and stabilization of the cyclobutenediones by the electron donating aryl groups.Key words: ketenes, furans, thiophenes, reactive intermediates, photolysis, mechanisms.

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11

Ahmed, Issahaku, Richard Tia i Evans Adei. "Exploring the peri-, chemo-, and regioselectivity of addition of technetium metal oxides of the type TcO3L (L = Cl–, O–, OCH3, CH3) to substituted ketenes: a DFT computational study". Canadian Journal of Chemistry 94, nr 5 (maj 2016): 523–32. http://dx.doi.org/10.1139/cjc-2015-0295.

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The addition of TcO3L (L = Cl, O–, OCH3, CH3) to substituted ketenes along various addition pathways was studied with density functional theory calculations to explore the peri-, chemo-, and regioselectivity of the reactions. In the reactions of TcO3L with dimethyl ketene, the results show that for L = O– and CH3, [1 + 1] addition to form a triplet zwitterionic intermediate is the preferred first step; for L = Cl, the [3 + 2]C=C addition across the O–Tc–Cl bond is the preferred first step and for L = OCH3 the [3 + 2]C=C addition across the O–Tc–OCH3 bond is the preferred first step. In the reactions of TcO3Cl with substituted ketenes, [1 + 1] addition to form a triplet zwitterionic intermediate is the preferred first step for X = Ph, CN, and Cl; the [3 + 2]C=C addition across the O–Tc–O bond of the complex is the preferred first step for X = H, while the [3 + 2]C=C addition across the O–Tc–CH3 bond is the preferred first step. Reactions involving a change in the oxidation state of metal have high activation barriers, while reactions that do not involve a change in oxidation state have low activation barriers. Reactions of ketenes with TcO3L complexes have lower activation barriers for the preferred addition pathways than those of the ReO3L complexes reported in the literature. Thus, the TcO3L complexes may be better catalysts for the activation of the C=C bonds of substituted ketenes than the reported ReO3L complexes.

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12

Paull, Daniel H., Anthony Weatherwax i Thomas Lectka. "Catalytic, asymmetric reactions of ketenes and ketene enolates". Tetrahedron 65, nr 34 (sierpień 2009): 6771–803. http://dx.doi.org/10.1016/j.tet.2009.05.079.

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13

Zhang, Zihao, Javier Pérez-Ramírez, Jeroen A. Van Bokhoven, Andras Bodi i Patrick Hemberger. "Operando Photoelectron Photoion Coincidence Spectroscopy to Detect Short-lived Intermediates in Catalysis". CHIMIA 77, nr 3 (29.03.2023): 132. http://dx.doi.org/10.2533/chimia.2023.132.

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Understanding the reaction mechanism is critical yet challenging in heterogeneous catalysis. Reactive intermediates, e.g., radicals and ketenes, are short-lived and often evade detection. In this review, we summarize recent developments with operando photoelectron photoion coincidence (PEPICO) spectroscopy as a versatile tool capable of detecting elusive intermediates. PEPICO combines the advantages of mass spectrometry and the isomer-selectivity of threshold photoelectron spectroscopy. Recent applications of PEPICO in understanding catalyst synthesis and catalytic reaction mechanisms involving gaseous and surface-confined radical and ketene chemistry will be summarized.

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14

A, Haydar, Mohammad Salim i Hassan H. Abdallah. "Theoretical Study for the [2+2] Cycloaddition Reaction Mechanism of Ketenes and their Derivatives". Oriental Journal Of Chemistry 35, nr 5 (29.10.2019): 1550–56. http://dx.doi.org/10.13005/ojc/350512.

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This study presents the intramolecular [2+2] cycloaddition reaction of ketenes to form cyclobutanones using B3LYP-D3/6-311++G(d,p) level of approximation. The concerted mechanism path was studied in detail. The structures of all intermediates and transition states were located using same level of theory. The influences of the substituents (-H, -CH3, -NH2, -F, -OH and –CN) were also discussed. The analysis of stationary points and the energetic parameters indicates that the substituted ketene with –CN group has the highest activation energy; however, ketene with –NH2 group has the lowest one. Conversely, in-tramolecular [2+2] cycloaddition records the highest degree of asynchronicity with –NH2 group and lowest with –CN group. The calculated thermodynamic parameters at room temperature have been listed and analyzed. The global and local properties of reactants involved in the intramolecular [2+2] cycloaddition reactions and the Fukui functions for an electrophilicity and local electrophilicity were also elucidated for carbon centers of each reactant.

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15

Wong, Ming Wah, i Curt Wentrup. "Ketene-Ketene Rearrangement: Substituent Effects on the 1,3-Migration in .alpha.-Oxo Ketenes". Journal of Organic Chemistry 59, nr 18 (wrzesień 1994): 5279–85. http://dx.doi.org/10.1021/jo00097a033.

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16

Kollenz, G. "Book Review, Ketenes". Synthesis 1996, nr 03 (marzec 1996): 419–22. http://dx.doi.org/10.1055/s-1996-4203.

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17

Haas, A., M. Lieb i H. W. Praas. "Bis(trifluoromethylchalkogeno)-ketenes". Journal of Fluorine Chemistry 45, nr 1 (październik 1989): 76. http://dx.doi.org/10.1016/s0022-1139(00)84451-6.

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18

MaGee, David I., Mahesh Ramaseshan i James D. Leach. "Synthesis of cyclic and acyclic imides, sulfonimides, and N-carbobenzyloxyamides by ketene trapping". Canadian Journal of Chemistry 73, nr 12 (1.12.1995): 2111–18. http://dx.doi.org/10.1139/v95-260.

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A convenient and general method for the synthesis of cyclic and acyclic imides, sulfonimides, and N-benzyloxycarbonyl amides via the inter-and intramolecular trapping of ketenes has been developed. Heating the corresponding amido, sulfonamido, and carbamamido ethyl ethynyl ethers at 150 °C for 3 h produced the desired compounds in good to excellent yields. Keywords: ketenes, imides, sulfonimides, N-benzyloxycarbonyl amides.

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19

Plüg, Carsten, Curt Wentrup, Kim Daasbjerg, Mihaela Pop, Ingrid Fussing, Henning Lund, Kurt V. Mikkelsen i Alexander Senning. "Ketenes from N-(2-Pyridyl)amides. Isolation of Methoxycarbonyl Ketenes." Acta Chemica Scandinavica 52 (1998): 654–55. http://dx.doi.org/10.3891/acta.chem.scand.52-0654.

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20

Qiao, Greg GuangHua, John Andraos i Curt Wentrup. "Reactivity of Ketenes in Matrices. Direct Observation of Ketene−Pyridine Ylides". Journal of the American Chemical Society 118, nr 24 (styczeń 1996): 5634–38. http://dx.doi.org/10.1021/ja9607190.

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21

WONG, M. W., i C. WENTRUP. "ChemInform Abstract: Ketene-Ketene Rearrangement: Substituent Effects on the 1,3-Migration in α-Oxo Ketenes". ChemInform 26, nr 10 (18.08.2010): no. http://dx.doi.org/10.1002/chin.199510066.

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22

Lystsova, Ekaterina A., Alexander S. Novikov, Maksim V. Dmitriev, Andrey N. Maslivets i Ekaterina E. Khramtsova. "Approach to Pyrido[2,1-b][1,3]benzothiazol-1-ones via In Situ Generation of Acyl(1,3-benzothiazol-2-yl)ketenes by Thermolysis of Pyrrolo[2,1-c][1,4]benzothiazine-1,2,4-triones". Molecules 28, nr 14 (18.07.2023): 5495. http://dx.doi.org/10.3390/molecules28145495.

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Acyl(imidoyl)ketenes are highly reactive heterocumulenes that enable diversity-oriented synthesis of various drug-like heterocycles. Such ketenes, bearing heterocyclic substituents, afford angularly fused pyridin-2(1H)-ones in their [4+2]-cyclodimerization reactions. We have utilized this property for the development of a new synthetic approach to pharmaceutically interesting pyrido[2,1-b][1,3]benzothiazol-1-ones via the [4+2]-cyclodimerization of acyl(1,3-benzothiazol-2-yl)ketenes generated in situ. The thermal behaviors of 3-aroylpyrrolo[2,1-c][1,4]benzothiazine-1,2,4-triones and 3-benzoylpyrrolo[2,1-b][1,3]benzothiazole-1,2-dione (two new types of [e]-fused 1H-pyrrole-2,3-diones reported by us recently) have been studied by thermal analysis and HPLC to elucidate their capability to be a source of acyl(1,3-benzothiazol-2-yl)ketenes. As a result, we have found that only 3-aroylpyrrolo[2,1-c][1,4]benzothiazine-1,2,4-triones are suitable for this. The experimental results are supplemented with computational studies that demonstrate that thermolysis of 3-aroylpyrrolo[2,1-c][1,4]benzothiazine-1,2,4-triones proceeds through an unprecedented cascade of two thermal decarbonylations. Based on these studies, we discovered a novel mode of thermal transformation of [e]-fused 1H-pyrrole-2,3-diones and developed a new pot, atom, and step economic synthetic approach to pyrido[2,1-b][1,3]benzothiazol-1-ones. The synthesized drug-like pyrido[2,1-b][1,3]benzothiazol-1-ones are of interest to pharmaceutics, since their close analogs show significant antiviral activity.

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23

Seikaly, Hani R., i Thomas T. Tidwell. "Addition reactions of ketenes". Tetrahedron 42, nr 10 (styczeń 1986): 2587–613. http://dx.doi.org/10.1016/s0040-4020(01)90545-9.

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24

Orr, Robert K., i Michael A. Calter. "Asymmetric synthesis using ketenes". Tetrahedron 59, nr 20 (maj 2003): 3545–65. http://dx.doi.org/10.1016/s0040-4020(03)00491-5.

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25

Rigsbee, E. M., C. Zhou, C. M. Rasik, A. Z. Spitz, A. J. Nichols i M. K. Brown. "Lewis acid-promoted [2 + 2] cycloadditions of alkenes with aryl ketenes". Organic & Biomolecular Chemistry 14, nr 24 (2016): 5477–80. http://dx.doi.org/10.1039/c5ob01837d.

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26

Andraos, J., A. J. Kresge i N. P. Schepp. "The hydration of mesitylketene in aqueous solution: detection of acid catalysis for an aromatic ketene". Canadian Journal of Chemistry 73, nr 4 (1.04.1995): 539–43. http://dx.doi.org/10.1139/v95-069.

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Mesitylketene was generated flash photolytically in aqueous solution by the photo-Wolff reaction of 2,4,6-trimethyldiazoacetophenone and also by rearrangement of mesitylynol obtained through photodecarbonylation of mesitylhydroxycyclopropenone, and rates of hydration of this ketene were measured in dilute perchloric acid, sodium perchlorate, and sodium hydroxide solutions as well as in concentrated sodium perchlorate and perchloric acid solutions. In dilute solution only an uncatalyzed reaction and a sodium-hydroxide-catalyzed process were observed, both of which could be attributed to nucleophilic attack, by water and by hydroxide ion, respectively, at the ketene carbonyl carbon atom. In concentrated sodium perchlorate solutions, a mild decrease in reaction rate with increasing salt concentration was observed, as expected on the basis of decreasing water activity and a consequent slowing of the uncatalyzed reaction. A similar mild decrease was found in perchloric acid solutions up to [Formula: see text] but this then gave way to a rate increase that became dominant above [Formula: see text] This appearance of acid catalysis indicates a change in reaction mechanism from nucleophilic attack of water to an electrophilic process involving rate-determining protonation on the β-carbon atom of the ketene group. Analysis of the acid-catalyzed reaction rate by the Cox–Yates method gives the catalytic coefficient [Formula: see text] This, when compared with [Formula: see text] for ketene itself, shows that the mesityl group retards acid-catalyzed hydration by a factor of 2200, and consequently the acid-catalyzed reaction of this, and other aromatic ketenes as well, becomes apparent only under strongly acidic conditions. Keywords: mesitylketene, ketene hydration, acid catalysis, Cox–Yates excess acidity correlation.

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27

Zakaszewska, Anna, Ewelina Najda-Mocarska i Sławomir Makowiec. "Evidence for an umpolung type of [2+2] cycloaddition of 2-carbamoyl ketenes". New Journal of Chemistry 41, nr 14 (2017): 6067–70. http://dx.doi.org/10.1039/c7nj00830a.

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28

Ghosh, Asitanga. "Formation of an exceptionally stable ketene during phototransformations of bicyclo[2.2.2]oct-5-en-2-ones having mixed chromophores". Beilstein Journal of Organic Chemistry 16 (15.09.2020): 2297–303. http://dx.doi.org/10.3762/bjoc.16.190.

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Photochemical reactions of bicyclo[2.2.2]oct-5-en-2-ones having mixed chromophores like a 5,6 dibenzoyl moiety and bulky electron-deficient substituents like phenyl or isopropenyl at the bridgehead position were analyzed for the first time in different solvents and upon irradiation with different wavelengths. In all cases, a regioselective photoinduced 1,5-phenyl migration leading to vinyl ketenes from the more congested site of the molecule to the less congested one has been observed. The ketenes were exceptionally stable both in air and solution. Its stability studies in acetonitrile through time-dependent UV absorption spectra revealed that it remained almost unchanged at least for a couple of weeks.

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Mondal, Mukulesh, Manashi Panda, Nicholas W. Davis, Vickie McKee i Nessan J. Kerrigan. "Asymmetric synthesis of cyclopentanones through dual Lewis acid-catalysed [3+2]-cycloaddition of donor–acceptor cyclopropanes with ketenes". Chemical Communications 55, nr 90 (2019): 13558–61. http://dx.doi.org/10.1039/c9cc07477e.

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Feuerstein, Wolfram, Paul Varava, Farzaneh Fadaei-Tirani, Rosario Scopelliti i Kay Severin. "Synthesis, structural characterization, and coordination chemistry of imidazole-based alkylidene ketenes". Chemical Communications 57, nr 87 (2021): 11509–12. http://dx.doi.org/10.1039/d1cc05161j.

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Zakaszewska, Anna, Ewelina Najda i Sławomir Makowiec. "The stereoselective formation of β-lactams with acyl ketenes generated from 5-acyl-Meldrum's acids". New Journal of Chemistry 40, nr 8 (2016): 6546–49. http://dx.doi.org/10.1039/c6nj00884d.

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Zaragozá, Ramón J., María J. Aurell i Miguel A. González-Cardenete. "A theoretical study on NHC-catalysed enantioselective cycloaddition of ketenes and 3-aroylcoumarins: mechanism and enantioselectivity". Organic & Biomolecular Chemistry 16, nr 30 (2018): 5474–82. http://dx.doi.org/10.1039/c8ob01035h.

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Wang, Qian-Yi, Teng-Fei Liu, Li-Feng Chu, Yun Yao i Chong-Dao Lu. "Chiral spiro phosphoric acid-catalysed enantioselective reaction of ketenes with N–H pyrroles". Chemical Communications 57, nr 90 (2021): 11992–95. http://dx.doi.org/10.1039/d1cc05307h.

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Dutta, B. C., K. K. Das i B. N. Goswami. "Cycloaddition Reaction: Synthesis of 5-Substituted 1,3,4-Thiadiazolo[3,2-a]pyrimidin-6-one". Journal of Chemical Research 23, nr 1 (styczeń 1999): 36–37. http://dx.doi.org/10.1177/174751989902300124.

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Ibrahim, Ahmad A., Divya Nalla, Maxwell Van Raaphorst i Nessan J. Kerrigan. "Catalytic Asymmetric Heterodimerization of Ketenes". Journal of the American Chemical Society 134, nr 6 (3.02.2012): 2942–45. http://dx.doi.org/10.1021/ja211678m.

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Szuromi, P. "Pulling for ketenes and imines". Science 349, nr 6254 (17.09.2015): 1297–98. http://dx.doi.org/10.1126/science.349.6254.1297-f.

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Staudaher, Nicholas. "Preparation of Aryl Alkyl Ketenes". Organic Syntheses 94 (2017): 1–15. http://dx.doi.org/10.15227/orgsyn.094.0001.

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Aliev, Z. G., O. P. Krasnykh, A. N. Maslivets, O. S. Stepanov, Yu S. Andreichikov i L. O. Atovmyan. "Chemistry of acyl(imidoyl)ketenes". Russian Chemical Bulletin 48, nr 11 (listopad 1999): 2127–30. http://dx.doi.org/10.1007/bf02494861.

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Aliev, Z. G., O. P. Krasnykh, A. N. Maslivets, Yu S. Andreichikov i L. O. Atovmyan. "Chemistry of acyl(imidoyl)ketenes". Russian Chemical Bulletin 48, nr 11 (listopad 1999): 2131–35. http://dx.doi.org/10.1007/bf02494862.

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Aliev, Z. G., O. P. Krasnykh, A. N. Maslivets, Yu S. Andreichikov i L. O. Atovmyan. "Chemistry of acyl(imidoyl)ketenes". Russian Chemical Bulletin 48, nr 3 (marzec 1999): 608–11. http://dx.doi.org/10.1007/bf02496191.

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Liu, Ronghau, Romeo M. Marra i Thomas T. Tidwell. "Phenyldimethylsilyl-Substituted Ketenes and Bisketenes". Journal of Organic Chemistry 61, nr 18 (styczeń 1996): 6227–32. http://dx.doi.org/10.1021/jo9605197.

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Szuromi, P. D. "CHEMISTRY: Of Ketenes and Carbenes". Science 288, nr 5471 (2.06.2000): 1549c—1549. http://dx.doi.org/10.1126/science.288.5471.1549c.

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Motoyoshiya, Jiro, i Kozo Hirata. "Cycloaddition Reactions of (Diethylphosphono)ketenes". Chemistry Letters 17, nr 2 (5.02.1988): 211–14. http://dx.doi.org/10.1246/cl.1988.211.

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Wamhoff, Heinrich. "Ketenes. By T. T. Tidwell". Angewandte Chemie International Edition in English 35, nr 18 (1.10.1996): 2153. http://dx.doi.org/10.1002/anie.199621531.

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Rafai Far, Adel. "Ketenes in Polymer-Assisted Synthesis". Angewandte Chemie International Edition 42, nr 21 (30.05.2003): 2340–48. http://dx.doi.org/10.1002/anie.200201594.

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BITTNER, J., i K. SEPPELT. "ChemInform Abstract: SF5-Substituted Ketenes." ChemInform 22, nr 5 (23.08.2010): no. http://dx.doi.org/10.1002/chin.199105142.

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Strating, J., J. Scharp i Hans Wynberg. "Ketenes with the adamantane skeleton". Recueil des Travaux Chimiques des Pays-Bas 89, nr 1 (2.09.2010): 23–31. http://dx.doi.org/10.1002/recl.19700890105.

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Tidwell, Thomas T. "Catalytic Asymmetric Esterification of Ketenes". Angewandte Chemie International Edition 44, nr 42 (28.10.2005): 6812–14. http://dx.doi.org/10.1002/anie.200501849.

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Liao, Jun-Yi, Qing-Yan Wu, Xiuqiang Lu, Ning Zou, Cheng-Xue Pan, Cui Liang, Gui-Fa Su i Dong-Liang Mo. "A copper-catalyzed diastereoselective O-transfer reaction of N-vinyl-α,β-unsaturated nitrones with ketenes into γ-lactones through [5 + 2] cycloaddition and N–O bond cleavage". Green Chemistry 21, nr 24 (2019): 6567–73. http://dx.doi.org/10.1039/c9gc01811e.

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Tang, Z., S. Mandal, N. D. Paul, M. Lutz, P. Li, J. I. van der Vlugt i B. de Bruin. "Rhodium catalysed conversion of carbenes into ketenes and ketene imines using PNN pincer complexes". Organic Chemistry Frontiers 2, nr 12 (2015): 1561–77. http://dx.doi.org/10.1039/c5qo00287g.

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