525-06-4Relevant articles and documents
Synthesis of 3-alkylseleno-2-cylcobutenone via [2+2] cycloaddition reaction of alkyneselenolate with diphenylketene
Koketsu, Mamoru,Kanoh, Masanori,Ishihara, Hideharu
, p. 805 - 807 (2002)
3-Alkylseleno-2-cyclobutenones were synthesized by reaction of alkyneselenolate with diphenylketene via [2+2] cycloaddition. The complete structure of the 2-cyclobutenone was determined by X-ray diffraction.
Concerted wolff rearrangement in two simple acyclic diazocarbonyl compounds
Burdzinski, Gotard,Zhang, Yunlong,Wang, Jin,Platz, Matthew S.
, p. 13065 - 13068 (2010)
The photochemistry of two simple acyclic diazo carbonyl compounds, azibenzil and diazoacetone, were studied using the tools of ultrafast time-resolved spectroscopy. In the former case, UV-vis detection allows observation of an absorption band of singlet benzoylphenylcarbene, decaying with a 740 ± 150 ps time-constant in acetonitrile. IR detection shows that the ketene product of Wolff rearrangement (～2100 cm-1) is formed by two parallel pathways: a stepwise mechanism with carbene intermediacy with a slow rise time-constant of 660 ± 100 ps, and directly in the diazo excited state as confirmed by the immediate formation of an IR band of a nascent hot ketene species. Photolysis (270 nm) of diazoacetone in chloroform leads mainly to the ketene species through a concerted process, consistent with the predominance of the syn conformation in the diazoacetone electronic ground state and a zero quantum yield of the internal conversion process.
Synthesis and time resolved infrared analysis of photochemical oxiranyl carbene and diphenyl ketene precursors
Tippmann, Eric M.,Curtis, Ryan
, p. 4785 - 4787 (2016)
Synthesis of a nonnitrogenous phenanthrene-based precursor of oxiranyl carbene yielded a photochemical source for diphenyl ketene after an in situ intramolecular rearrangement. The initial carbene precursor targeted rearranged from a putative spiro-oxiranyl intermediate to a cyclobutanone. Photolysis of the phenanthrene–cyclobutanone generated an infrared signal centered at 2100?cm?1consistent with diphenyl ketene formation. Time-resolved infrared spectroscopy followed the reaction progress and measured bimolecular rate constants (kobs?=?9.1?×?106?M?1?s?1; butyl amine) consistent with diphenyl ketene formation. Quenching experiments combined with Stern–Volmer kinetics suggests a radical pathway is likely involved in the formation of diphenyl ketene from the phenanthrene-based precursor. The generality of the rearrangement is also discussed.
Synthesis of γ-Lactams by Formal Cycloadditions with Ketenes
Viceriat, Audrey,Marchand, Isabelle,Carret, Sébastien,Poisson, Jean-Fran?ois
supporting information, p. 2449 - 2454 (2021/04/05)
The synthesis of γ-lactams is reported by a formal (3+2) cycloaddition between readily available ketenes and aziridines or a one-pot formal (2+1+2) cycloaddition using imines as aziridine precursors. The method is practical, is scalable, and affords high yields. It also offers a high level of regio- and diastereoselectivity on a wide range of substrates as well as a high stereoselectivity in the case of enantiopure aziridines.
Coordination behaviors of diphenylketene adsorbed in the nanocages of zeolite NaY and AgY
Shibata, Shintaro,Masui, Yoichi,Onaka, Makoto
, p. 663 - 670 (2020/12/29)
We investigated in detail how polar cumulene molecules like diphenylketene were accommodated in faujasite zeolite pores based on 13C CP/MAS and DD/MAS NMR analyses as well as quantum chemical calculations after adsorbing the molecule into the zeolite NaY or AgY having “hard” sodium ions or “soft” silver ions. Since the diphenylketene has such a specific structure that a carbonyl group (a hard base) is accumulated by a carbon-carbon double bond (a soft π base), which is conjugated with two benzene rings (soft π bases), it is possible for the diphenylketene to adopt multicoordination modes to different metal ions in the zeolite. Compared with the coordination modes of benzophenone and 1,1-diphenylethene adsorbed in the NaY and AgY, those of diphenylketene were identified, and specific coordination behaviors in the zeolite’s supercages were classified depending on the hard or soft metal characters: The C=O and phenyl coordination modes to Na+ in NaY prevail, while the C=C and phenyl coordination to Ag+ in AgY is favored. We also unveiled the difference in the molecular mobility depending on the types of cations in the zeolite by comparing the 13C CP/MAS and DD/MAS NMR spectra.
A photoinduced Wolff rearrangement/Pd-catalyzed [3+2] cycloaddition sequence: An unexpected route to tetrahydrofurans
Liu, Jie,Li, Miao-Miao,Qu, Bao-Le,Lu, Liang-Qiu,Xiao, Wen-Jing
supporting information, p. 2031 - 2034 (2019/02/19)
A novel sequential reaction that combines a visible light-induced Wolff rearrangement of α-diazoketones and a Pd-catalyzed [3+2] cycloaddition of vinyl cyclopropanes with the resulting ketenes is described in this work. Selective O-allylic alkylation was observed over C-allylic alkylation, which unexpectedly led to a series of highly functionalized tetrahydrofurans with high efficiency (20 examples, 58-99% yields).
Ketenes from N-(2-Pyridyl)amides
Plüg, Carsten,Kanaani, Hussein,Wentrup, Curt
, p. 687 - 692 (2015/04/27)
Methoxycarbonylketene 4a, methoxycarbonyl(methyl)ketene 4b, chloroketene 4c, cyanoketene 4d, diphenylketene 4e, and 2-pyridylketene 4f have been generated by flash vacuum thermolysis of the corresponding 2-pyridylacetamide derivatives 3a-f and isolated in Ar matrices for FT-IR spectroscopic characterisation. The N-(2-pyridyl)-2-pyridylacetamide 3f yielded 2-pyridyl isocyanate in addition to 2-pyridylketene.
Thermal [2+2]-cycloadditions of diphenylketene with aryl- and hetaryl-substituted thioketones
Mlosto, Grzegorz,Urbaniak, Katarzyna,Szychowska, Anna,Linden, Anthony,Heimgartner, Heinz
, p. 529 - 539 (2015/03/04)
The reaction of diphenylketene (1) with aryl- and hetaryl-substituted thioketones (2) gave the corresponding 3,3,4,4-tetraarylthietan-2-ones (3) in good yields. Remarkably, the reactions with bis-hetaryl-substituted thioketones occurred significantly faster compared with those involving the bis-aryl-substituted thioketones. The structure of compound 3c has been established by X-ray crystallography.
Synthesis, electronic structure and reactivity of bis(imino)pyridine iron carbene complexes: Evidence for a carbene radical
Russell, Sarah K.,Hoyt, Jordan M.,Bart, Suzanne C.,Milsmann, Carsten,Stieber, S. Chantal E.,Semproni, Scott P.,Debeer, Serena,Chirik, Paul J.
, p. 1168 - 1174 (2014/03/21)
The reactivity of the disubstituted diazoalkane, N2CPh 2 with a family of bis(imino)pyridine iron dinitrogen complexes was examined. For the most sterically protected member of the series, ( iPrPDI)Fe(N2)2 (iPrPDI = 2,6-(2,6-iPr2C6H3NCMe) 2C5H3N), an S = 1 iron diazoalkane complex was obtained and structurally characterized. Reducing the size of the 2,6-aryl substituents to ethyl or methyl groups resulted in isolation of bis(imino)pyridine iron carbene complexes. Magnetic measurements established S = 1 ground states, demonstrating rare examples of iron carbenes in a weak ligand field. Electronic structure determination using metrical parameters from X-ray diffraction as well as Moessbauer, XAS and computational data established high-spin iron(ii) compounds engaged in antiferromagnetic coupling with redox-active bis(imino)pyridine and carbene radicals. The Royal Society of Chemistry 2014.
Lewis acid-promoted ketene-alkene [2 + 2] cycloadditions
Rasik, Christopher M.,Brown, M. Kevin
supporting information, p. 1673 - 1676 (2013/04/10)
Described are the first examples of ketene-alkene [2 + 2] cycloadditions promoted by Lewis acids. Notable features of this method include (1) substantial rate acceleration relative to traditional thermal reactions, (2) good diastereoselectivities and yields for the formation of the cyclobutanone products, and (3) inverse diastereoselectivity compared with related thermal cycloadditions for many examples. These studies not only provide access to synthetically versatile cyclobutanones that cannot be prepared by traditional thermal cycloadditions but also address important mechanistic questions regarding ketene-alkene [2 + 2] cycloaddition reactions.
