Synthesis, functionalization, and isolation of planar-chiral pillar[5]arenes with bulky substituents using a chiral derivatization agent.

Bulky perneopentyloxy-pillar[5]arene (Pillar-1) was synthesized and its conformational mobility was investigated using variable-temperature 1 H NMR spectroscopy. The host-guest interactions between Pillar-1 and n -octyltrimethylammonium hexafluorophosphate (OMA) were investigated, and the formation of a 1 : 1 complex was revealed via 1 H NMR. Planar-chiral isomers were synthesized via the reaction of a hydroxy-functionalized pillar[5]arene with chiral derivatization agent ( S )-(+)-MTPA-Cl. The (Sp, R )-and (Rp, R )-forms of the pillar[5]arene diastereomers were isolated by HPLC, and their structures were analyzed by 19 F NMR. HPLC measurements indicated that racemization did not take place at 40 °C for 72 h.