C−N Bond Activation and Ring Opening of a Saturated N‐Heterocyclic Carbene by Lateral Alkali‐Metal‐Mediated Metalation

Combining alkali‐metal‐mediated metalation (AMMM) and N‐heterocyclic carbene (NHC) chemistry, a novel C−N bond activation and ring‐opening process is described for these increasingly important NHC molecules, which are generally considered robust ancillary ligands. Here, mechanistic investigations on reactions of saturated NHC SIMes ( SIMes =[:C{N(2,4,6‐Me 3 C 6 H 2 )CH 2 } 2 ]) with Group 1 alkyl bases suggest this destructive process is triggered by lateral metalation of the carbene. Exploiting co‐complexation and trans‐metal‐trapping strategies with lower polarity organometallic reagents (Mg(CH 2 SiMe 3 ) 2 and Al(TMP ) iBu 2 ), key intermediates in this process have been isolated and structurally defined.