Abnormal NHC carbenes

23 October 2009 - Check this out

abnormal NHC Bertrand 2009
Check: Abnormal NHC carbenes (aNHC)
Check: variation of NHC carbene , a type of carbene that is stable at ambient temperature and can be isolated. In the regular NHC carbene carbon is flanked by two nitrogen atoms, in the aNHC it is just one. Requires steric protection by bulky diisopropylphenyl (dip) ligands. Central ring planar with 1.5 bond order bond lenghts consistent with ring delocalization. carbon NMR also indicates carbene.
Check: Published in Science , Aldeco-Perez et al. 2009 DOI Bertrand lab
Check: Substrate a imidazolium ion
Check: reagent KHMDS, a strong base removes the C5 proton
Check: utility as novel catalyst
Check: more on Guy Bertrand in this blog here, here and here