Strain‐Driven Formal [1,3]‐Aryl Shift within Molecular Bows

Abstract

Delving into the influence of strain on organic reactions in small molecules at the molecular level can unveil valuable insight into developing innovative synthetic strategies and structuring molecules with superior properties. Herein, we present a molecular‐strain engineering approach to facilitate the consecutive [1,2]‐aryl shift (formal [1,3]‐aryl shift) in molecular bows (MBs) that integrate 1,4‐dimethoxy‐2,5‐cyclohexadiene moieties. By introducing ring strain into MB through tethering the bow‐limb, we can harness the intrinsic mechanical forces to drive multistep aryl shifts from para‐ to meta‐ to ortho‐position.Through exercise of precise intramolecular strain, the seemingly impractical [1,3]‐aryl shift was realized, resulting in the formation of ortho‐disubstituted products. The solvent and temperature play a crucial role in the occurrence of the [1,3]‐aryl shift.The free energy calculations with inclusion of solvation support a feasible mechanism, which entails multistep carbocation rearrangements, for the formal [1,3]‐aryl shift. By exploring the application of molecular strain in synthetic chemistry, this research offers a promising direction for developing new tools and strategies towards precision organic synthesis.