Confused‐Prism[5]arene: a Conformationally Adaptive Host by Stereoselective Opening of the 1,4‐Bridged Naphthalene Flap

The confused‐prism[5]arene macrocycle (c‐PrS[5]Me) shows conformational adaptive behavior in the presence of ammonium guests. Upon guest inclusion, the 1,4‐bridged naphthalene flap reverses its planar chirality from pS to pR (with reference to the pS(pR)4 enantiomer). Stereoselective directional threading is also observed in the presence of directional axles, in which up/down stereoisomers of homochiral (pR)5‐c‐PrS[5]Me pseudorotaxanes are formed. All change, all together: The confused‐prism[5]arene host changes its planar chirality upon the complexation of ammonium guests, adopting the homochiral all‐pR (or all‐pS) conformation. Stereoselective directional threading was also observed in the presence of directional ammonium axles, resulting in the formation of pseudorotaxanes in which the prismarene wheel adopts homochiral all‐pR (all‐pS) conformation.