3173-79-3Relevant academic research and scientific papers
Phosphine-catalyzed stereoselective dimerizations of ketenes
Ibrahim, Ahmad A.,Wei, Pei-Hsun,Harzmann, Gero D.,Nalla, Divya,Mondal, Mukulesh,Wheeler, Kraig A.,Kerrigan, Nessan J.
, (2020/12/21)
Full details of optimisation studies of the phosphine-catalyzed ketene homodimerization reaction and the detailed development of an asymmetric variant are discussed. Studies towards the development of a phosphine-catalyzed ketene heterodimerization reaction are revealed. A discussion of possible reaction mechanisms for the dimerization reactions, supported by spectroscopic analysis of intermediates and trapping experiments, is also presented.
Josiphos-catalyzed asymmetric homodimerization of ketoketenes
Ibrahim, Ahmad A.,Wei, Pei-Hsun,Harzmann, Gero D.,Kerrigan, Nessan J.
experimental part, p. 7901 - 7904 (2011/03/19)
In this paper the development of a chiral phosphine-catalyzed homodimerization of ketoketenes that provides access to a variety of highly substituted ketoketene dimer β-lactones (11 examples) is reported. The Josiphos catalytic system displays good to exc
Mechanistic studies of the phosphine-catalyzed homodimerization of ketoketenes
Wei, Pei-Hsun,Ibrahim, Ahmad A.,Mondal, Mukulesh,Nalla, Divya,Harzmann, Gero D.,Tedeschi, Frank A.,Wheeler, Kraig A.,Kerrigan, Nessan J.
supporting information; experimental part, p. 6690 - 6694 (2011/02/24)
The mechanism of PBu3-catalyzed homodimerization of ketoketenes has been explored and compared with that of the previously reported trialkylphosphite-mediated reactions. NMR studies of the PBu3- catalyzed reaction implicated the involvement of tetravalent phosphonium intermediates. Phosphonium intermediates in the catalytic cycle were trapped through reaction with trimethylsilyl chloride and 4-chlorobenzaldehyde, and the resulting products were characterized. A method for the stoichiometric generation of phosphonium enolates was developed as a result of these studies. No evidence was obtained for the involvement of pentacovalent phosphorane intermediates in trialkylphosphine-catalyzed ketoketene homodimerization reactions, in contrast with the mechanism of the trialkylphosphite-mediated homodimerization of dimethylketene. An X-ray crystal structure analysis of methylphenylketene dimer showed that it possesses Z-geometry about the exocyclic olefin.
Insights into the formation of symmetrical trimers of dialkylated ketenes starting from acid chloride precursors
Saaidi, Pierre-Loic,Doridot, Gabriel,Jeanneau, Erwann,Hasserodt, Jens
, p. 1011 - 1018 (2008/03/17)
Application of known dialkyl ketene di- and trimerization to more complex precursors could readily open the route to highly functionalized symmetrical cyclobuta-1,3-diones and cyclohexa-1,3,5-triones. We report herein the results on three substrates containing either a C=C double bond or a protected glycol moiety as illustrative functionalized groups. The nature of the substituents is found to be crucial: while cyclopentenyl and more constrained dioxolanocyclopentenyl precursors efficiently dimerize, a diallylic derivative fails. At the millimolar scale, methoxide-catalyzed trimerization shows limited reproducibility, even for the reported substrate tetramethylcyclobuta-1,3-dione. However, systematic studies, including the use of microwaves, demonstrate that formation of symmetrical trimers is favored under solvent-free conditions and conventional heating, which allowed us to isolate and characterize trispiro[4.1.4.1.4.1]octadeca-2,9,15-triene-6,12,18-trione.
Ketene. Part 26. The Reactions of 3,4-Dihydroisoquinoline N-Oxide with Ketenes, and an Attempted Synthesis of 3,4-Dihydro-3,3-dimethylquinoline N-Oxide
Evans, Andrew R.,Martin, Russell,Taylor, Giles A.,Yap, C. H. Maurice
, p. 1635 - 1640 (2007/10/02)
3,4-Dihydroisoquinoline N-Oxide reacts with dimethylketene to form a 1:2 adduct (8) in addition to compounds (6) and (7).With cyano-t-butylketene and ethoxycarbonyl-t-butylketene the adducts (9a) and (9b) are formed. 3,3-Dimethyl-1,2,3,4-tetrahydroquinoline (21a) has been synthesized, but attempts to convert this into the nitrone (20b) were unsuccessful.
