New chiral cyclohexylhemicucurbit[6]uril

Abstract

The first enantiomerically pure members of the cucurbituril family, (all-S)- and (all-R)-cyclohexylhemicucurbit[6]urils (cycHC), were synthesized in good yield (up to 85%). The crystal structure of this new macrocycle clearly shows its ball-like shape. CycHC monomers adopt a "zigzag" conformation, having apolar cyclohexyls around the openings and polar ureas in the middle. Cyclohexylhemicucurbit[6]urils formed complexes with halides, carboxylic acids and amines and diastereomeric complexes with methoxyphenylacetic acid in organic media. The association constants of cycHC with small organic compounds were evaluated by diffusion NMR in chloroform.