Selection of Planar Chiral Conformations between Pillar[5,6]arenes Induced by Amino Acid Derivatives in Aqueous Media

Chiral α‐amino acids play critical roles in the metabolic process in nearly all life forms. So far, chiral recognition of α‐amino acids has mainly focused on the determination of l / d enantiomers. Herein, selection of planar chiral conformations between water‐soluble pillar[5]arene WP5 and pillar[6]arene WP6 was observed due to α‐side chain or ethyl ester moieties of l ‐α‐amino acid ethyl ester hydrochlorides binding with WP5 and WP6 , respectively. Therefore, α‐side chain and ethyl ester moieties of l ‐α‐amino acid ethyl ester hydrochlorides were recognized by observing the induced CD signal and its inversion. This is a rare example of being able to detect the chiral region around α‐carbon of a chiral α‐amino acid molecule.