Twisted Allenyl-Pyridocyclophanes by Templated Cyclooligomerization: Chiral Cavities for Precision Molecular Recognition

We report the palladium-catalyzed one-pot synthesis of enantiopure 20-, 30-, and 40-membered cyclophanes shaped by axially twisted allene units. Under Cs⁺-template, the two smaller macrocycles (<b>2</b> and <b>3</b>) are favored over the largest (<b>4</b>). X-ray studies reveal that <i>rac</i>-<b>2</b> assembles into homochiral helices that pack to form channels, while <i>rac</i>-<b>3</b> forms racemic dimers. These shape-persistent hosts, with unique chiral 3D cavities, undergo guest-induced conformational switching and (enantio)-selectively bind diols and ammonium cations, including hydroxycarboxylic acids and α-hydroxyammoniums, as evidenced by diagnostic ECD shifts.