Please use this identifier to cite or link to this item:
|Title:||Catalytic annulation of heterocycles via a novel redox process involving the imidazolium salt N-heterocyclic carbene couple|
|Citation:||Normand, A.T., Yen, S.K., Huynh, H.V., Hor, T.S.A., Cavell, K.J. (2008-07-14). Catalytic annulation of heterocycles via a novel redox process involving the imidazolium salt N-heterocyclic carbene couple. Organometallics 27 (13) : 3153-3160. ScholarBank@NUS Repository. https://doi.org/10.1021/om800140n|
|Abstract:||A novel atom-efficient catalytic reaction, which converts imidazolium salts, with N-butenyl, N-substituted butenyl, and N-pentenyl substituents, into five- and six-membered fused-ring imidazolium and thiazolium salts has been developed. The reaction proceeds through azolium, C2-H, oxidative addition to Ni(O) followed by intramolecular insertion of the N-alkenyl double bond into the Ni hydride to give an intramolecularly bound carbene-Ni-alkyl intermediate. Reductive elimination of the linked carbene and alkyl groups gives the fused-ring azolium products and regenerates the Ni(0) catalyst. Products are potential building blocks for the synthesis of pharmaceuticals and novel ionic liquids. For example, 1,7-dimethyl-6,7-dihydro-5H-pyrrole[l,2-α] imidazolium bromide (2f), a five-membered fused-ring imidazolium salt, is formed from the catalytic ring closing of l-butenyl-3-methylimidazolium bromide (1f). The reaction proceeds at moderate temperatures (50 °C) to give the products in high yield and selectivity. The catalyst was formed in situ from Ni(COD) 2 plus added ligand L (where L = IMes, SMes, IPr, SPr, 4,5-Me 2IPr, PPh3, PCy3, PCy2(Biphenyl), P'Bu3) in DMF. © 2008 American Chemical Society.|
|Appears in Collections:||Staff Publications|
Show full item record
Files in This Item:
There are no files associated with this item.
checked on Nov 13, 2018
WEB OF SCIENCETM
checked on Nov 5, 2018
checked on Nov 9, 2018
Items in DSpace are protected by copyright, with all rights reserved, unless otherwise indicated.