Ring Contraction by Rearrangement of Sterically Congested Cyclic (Amino)(aryl)carbenes.

The rearrangement of sterically congested cyclic (amino)(aryl)carbenes (CAArCs) by the reaction of related iminium salts with potassium bis(trimethylsilyl)amide is reported, allowing for forming benzocyclobutanimines via a ring contraction process. Mechanistic studies by theoretical calculations indicate that the formation of conjugated ketenimines as intermediates could be considered, in which steric hindrance caused by N -alkyl motifs of CAArCs plays an important role in promoting the ring-opening by the cleavage of C-N bond.