Merging Annulation with Ring Deconstruction: Synthesis of ()-3-(2-Acyl-1-benzo[]imidazol-4-yl)acrylaldehyde Derivatives via I/FeCl-Promoted Dual C(sp)-H Amination/C-N Bond Cleavage.

An unprecedented I/FeCl-promoted cascade reaction of aryl methyl ketones with 8-aminoquinolines for the convenient synthesis of ()-3-(2-acyl-1-benzo[]imidazol-4-yl)acrylaldehydes was developed by merging annulation with ring deconstruction. This novel strategy unlocked the new reactivity of 8-aminoquinolines and provided an attractive platform for the ring opening of unactivated -heteroaromatic compounds. Preliminary mechanistic investigation suggested that dual C(sp)-H amination/C-N bond cleavage were key reaction steps. Furthermore, late-stage modification of the obtained products successfully delivered pyrazole and isoxazole derivatives, increasing the practicability and application potential of this methodology in organic synthesis.