- A stereoselective palladium-mediated reductive coupling of electron-deficient terminal iodoalkenes
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Iodoacrylate esters undergo palladium-catalysed reductive homocoupling to derive dienyl diester derivatives. This reductive coupling can be extended to ester-substituted terminal iododienes to derive tetraene diesters. In all cases, the reactions show relatively high levels of stereocontrol, which shows an inversion of stereochemistry about one iodoalkene unit. This process, and the suggestion that the reaction releases diiodine, is consistent with a syn-1,2-addition of an iodopalladium(II)-alkene species across another iodoalkene unit (carbometallation step), followed by reductive syn-elimination of iodopalladium iodide to derive palladium(II) iodide. It appears that under the reaction conditions employed, palladium(II) iodide may equilibrate to palladium(O) and diiodine, which can be observed or trapped out from the reaction mixture.
- Batsanov, Andrei S.,Knowles, Jonathan P.,Samsam, Benedict,Whiting, Andrew
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supporting information; experimental part
p. 227 - 233
(2009/04/11)
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- An Efficient and Selective Pallladium-catalysed Oxidative Dicarbonylation of Akynes to Alkyl- or Aryl-maleic Esters
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Terminal alkyne dicarbonylation can be readily effected under mild conditions by treating alkynes with carbon monoxide and alcohols or water at 25-80 deg C in the presence of PdI2, KI and air, with unprecedented catalytic efficiency.Dicarbonylation products are mainly maleic esters or acids and their ring-chain tautomers.The latter are formed to a large extent at room temperature.Reaction pathways are discussed.
- Gabriele, Bartolo,Costa, Mirco,Salerno, Giuseppe,Chiusoli, Gian Paolo
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