Enantioselective recognition of ammonium perchlorate salts by optically active monoaza-15-crown-5 ethers

Chiral monoaza-15-crown-5 ethers (1, 2) were prepared from (R)-(-)-2-amino-1-butanol in high yield. The chiral monoaza-15-crown-5 ethers were purified directly as NaClO4 complexes. Molecular recognition by these chiral monoaza-crown ethers of (R)- and (S)-PhEtHClO4 and (R)- and (S)-NapEtHClO(4) as characterized by UV-vis spectroscopy. The order of enantiomeric selectivity is (R)- > (S)- PhEtHClO4 and (S)- > (R)-NapEtHClO(4) for 1. In the case of 2 it was (R)- > ($)-PhEtHClO4 and (R)- > (S)-NapEtHClO(4). The cavity of macrocycle and steric hindrance of the benzene units appears to play an important role in recognition. (C) 2004 Wiley-Liss, Inc.