Acid-Promoted Rearrangement of Carbonate Functionality Anchored to the Lower Rim of a Calix[4]arene Skeleton:  A New Class of Chiral Calix[4]arene and Its Chiroptical Properties

A unique calix[4]arene lower-rim intramolecular rearrangement, resulting in molecular asymmetry arising from the upper- and lower-rim substitution pattern, produces a new class of inherently chiral calix[4]arenes in a partial cone conformation. This was aided by molecular rigidification arising from π−π and C−H···π interactions between bulky lower-rim substituents, with the corresponding circular dichroism spectra exhibiting the most intense bisignate Cotton effects yet observed for calix[4]arenes not bearing a chiral center.