Deprotonation Attempts on Imidazolium Salt Tethered by Substituted Phenol and Construction of Its Magnesium Complex by Transmetalation

Several attempts to deprotonate the imidizolium salt
1-methyl-3-(4,6-di-tert-butyl-2-hydroxybenzyl)imidazolium bromide, H2[CO]Br (4), tethered by substituted phenol to yield
anonic carbene species M[CO] (M = Li, Na) resulted in the
formation of {Na[ON](THF)}2 (5) and {Li[ON](THF)}2 (6) (1-methyl-2-(4,6-di-tert-butyl-2-hydroxybenzyl)imidazole, H[ON])
after warming to room temperature from −78 °C due to 1,2-aryloxy migration. Treatment of in-situ-generated M[CO] with
1.0 equiv of MesMgBr (Mes = 2,4,6-Me3C6H2) produced a rare
magnesium NHC complex, {Mg[OC](Mes)}2 (8). Both 5 and 8
have been characterized by an X-ray diffraction study.