1255944-75-2Relevant 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.
, (2021)
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.
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.
Josiphos-catalyzed asymmetric homodimerization of ketoketenes
Ibrahim, Ahmad A.,Wei, Pei-Hsun,Harzmann, Gero D.,Kerrigan, Nessan J.
scheme or table, 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
