598-26-5Relevant academic research and scientific papers
Environment Effects on the ESR Spectrum of the Cation Radical of Dimethylketene in Low Temperature Matrices
Fujisawa, Jun,Shimokoshi, Kazuo,Shida, Tadamasa
, p. 1267 - 1272 (1985)
The cation radical of dimethylketene produced in γ-irradiated solid solutions of various halocarbons has been investigated by ESR over a temperature range from 77 K to the melting point of each matrix.The cation radical in CCl4 was stable up to about 180 K and the spectrum was well resolved to allow the determination of the anisotropic ESR parameters.In CCl2FCClF2 and CCl2FCCl2F, a series of irreversible spectral changes was observed with an increase in temperature.This process was interpreted in terms of the formation of the dimer cation.In the matrix of CCl3F, the ESR spectrum exhibited extra structure, which varied reversibly with temperature.The analyses of the spectra suggested that the cation radical in CCl3F weakly interacts with surrounding matrix molecules to form adducts.
Methyl- and Dimethylketene: He I Photoelectron Spectra and Vertical Ionization Potentials Calculated by Using Perturbation Corrections to Koopmans' Theorem
Chong, D. P.,Westwood, N. P. C.,Langhoff, S. R.
, p. 1479 - 1481 (1984)
He I photoelectron spectra are reported for the monomethyl and dimethyl derivatives of ketene, H2CCO.The spectra, which beyond the first structured ionization potential show a complicated series of bands in the 12-18-eV range, have been fully assigned by using calculations employing perturbation corrections to Koopmans' theorem.
Lessons in Strain and Stability: Enantioselective Synthesis of (+)-[5]-Ladderanoic Acid
Hancock, Erin N.,Kuker, Erin L.,Tantillo, Dean J.,Brown, M. Kevin
supporting information, p. 436 - 441 (2019/11/25)
The synthesis of structurally complex and highly strained natural products provides unique challenges and unexpected opportunities for the development of new reactions and strategies. Herein, the synthesis of (+)-[5]-ladderanoic acid is reported. En route to the target, unusual and unexpected strain release driven transformations were uncovered. This occurrence required a drastic revision of the synthetic design that ultimately led to the development of a novel stepwise cyclobutane assembly by an allylboration/Zweifel olefination sequence.
Thioallenoates in catalytic enantioselective [2+2]-cycloadditions with unactivated alkenes
Conner, Michael L.,Wiest, Johannes M.,Brown, M. Kevin
supporting information, p. 3265 - 3271 (2019/05/04)
The application of thioallenoates to catalytic enantioselective [2+2]-cycloadditions with unactivated alkenes is reported. In many cases, the thioallenoates examined exhibit superior reactivity and selectivity compared to the allenic esters generally used in these cycloadditions.
PROCESS FOR PREPARING 2,2,4,4-TETRAMETHYL-1,3-CYCLOBUTANEDIOL
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Paragraph 0075-0093, (2019/10/22)
The present invention refers to 2, 2, 4, 4 - tetramethyl - 1, 3 - cyclohexanedimethanol bhutan d this year a number bath method disclosure as follows. the method (A) meta acrylic acid (methacrylic acid, MAA) removed from the raw material (B) use as an intermediate in the mote [lik [lik] it buys [...] (isobutyric acid, IBA), 2, 2, 4, 4 - tetramethyl - 1, 3 - cyclohexanedimethanol [...] (C) dimethyl ketene (dimethyl Ketene, DMK) and (D) (2, 2, 4, 4 a-tetramethyl-a 1, 3 non-cyclobutanedione, CBDK) via a final material sequentially (E) 2, 2, 4, 4 - tetramethyl bhutan d this year cycle - 1, 3 - (2, 2, 4, 4 a-tetramethyl-a 1, 3 non-cyclobutanediol, CBDO) bath a number comprise substrate. According to the present invention number bath step optimization and a green protective environmental 2, 2, 4, 4 - tetramethyl - 1, 3 - cyclohexanedimethanol bhutan d this year through mirror number is encoded number bath method is highly lipophilic ball number. (by machine translation)
Fe-Catalyzed Cycloisomerization of Aryl Allenyl Ketones: Access to 3-Arylidene-indan-1-ones
Teske, Johannes,Plietker, Bernd
supporting information, p. 2257 - 2260 (2018/04/27)
A cycloisomerization of aryl allenyl ketones to 3-arylidene-indan-1-ones using a cationic Fe-complex as a catalyst is reported. The catalyst opens a synthetically interesting reaction pathway to this surprisingly underrepresented class of indanones that are not accessible using alternative catalytic systems.
Tfoh-catalyzed formal [3 + 2] cycloaddition of cyclopropane 1,1-diesters with nitriles
Cui, Bo,Ren, Jun,Wang, Zhongwen
, p. 790 - 796 (2014/04/03)
A triflic acid-catalyzed formal [3 + 2] cycloaddition of cyclopropane 1,1-diesters with nitriles was developed. This reaction was expeditious, and the scope of the substituents in both cyclopropanes and nitriles was broad. This supplies an efficient and practical method for the synthesis of 1-pyrrolines.
Catalytic asymmetric heterodimerization of ketenes
Ibrahim, Ahmad A.,Nalla, Divya,Van Raaphorst, Maxwell,Kerrigan, Nessan J.
supporting information; experimental part, p. 2942 - 2945 (2012/04/10)
In this Communication we describe an unprecedented catalytic asymmetric heterodimerization of ketenes of wide substrate scope. The alkaloid-catalyzed method provides access to ketene heterodimer β-lactones and allows even two different monosubstituted ketenes to be cross-dimerized, with excellent enantioselectivity (17 examples with ≥90% ee) and excellent heterodimer regioselectivity observed in all cases.
Decomposition of malonic anhydrides
Perrin, Charles L.,Flach, Agnes,Manalo, Marlon N.
experimental part, p. 9698 - 9707 (2012/07/14)
Malonic anhydrides decompose at or below room temperature, to form a ketene and carbon dioxide. Rate constants for the thermal decomposition of malonic, methylmalonic, and dimethylmalonic anhydrides were measured by NMR spectroscopy at various temperatures, and activation parameters were evaluated from the temperature dependence of the rate constants. Methylmalonic anhydride is the fastest, with the lowest δH?, and dimethylmalonic anhydride is the slowest. The nonlinear dependence on the number of methyl groups is discussed in terms of a concerted [2s + (2s + 2s)] or [2s + 2a] cycloreversion that proceeds via a twisted transition-state structure, supported by computations.
Mild decarboxylative activation of malonic acid derivatives by 1,1′-carbonyldiimidazole
Lafrance, Danny,Bowles, Paul,Leeman, Kyle,Rafka, Robert
supporting information; scheme or table, p. 2322 - 2325 (2011/06/26)
Chemical equations presented. Malonic acid derivatives undergo unusually mild decarboxylation when treated with N,N′-carbonyldiimidazole (CDI) at room temperature to generate the carbonyl imidazole moiety in high yield, which can be reacted further with a variety of nucleophiles in an efficient one-pot process.
