Wilcox Molecular Torsion Balance with Rigid Side Arm and Separable Atropisomers for Investigating CH−π Interactions

Abstract

A new variant of the Wilcox molecular torsion balance featuring a naphthyl-alkyl side arm was synthesized. The energy barrier for axial isomerization in the new balance was sufficiently high to allow for separation of the two rotamers and to observe their isomerization kinetics. The CH−π interaction energies in derivatives of the new and the original ester balance were in close agreement, suggesting that the motion in ester linkage is not an important factor in folding in the ester balance