Stereoelectronic effects in force-accelerated retro-Diels–Alder reactions

In polymer mechanochemistry, mechanosensitive molecules
(mechanophores) are activated upon elongation of anchored polymer arms. The reactivity of a mechanophore can be influenced by a variety of structural factors, including the geometry of attachment of the polymer arms and the nature of eventual substituents. Here we investigate stereoelectronic effects in force-accelerated Diels–Alder reactions using the CoGEF (Constrained Geometries simulate External Force) calculation method. We found that the presence of an electron-donating heteroatom on the diene leads to a lower activation force, and that the mechanochemical reactivity is suppressed when the anchor group is attached to a central rather than lateral position.