Synthesis and Complexation Properties of Some Novel Lariat-Crown Ethers

Summary.  Several new lariat-crown ethers bearing either bridged bisdioxine or tetraoxaadamantane units as chiral substituents are prepared by reacting the corresponding amino-crown ether derivatives with the dimeric α-oxoketene, the latter obtained by flash vacuum pyrolysis of a furan-2,3-dione precursor. Complexation properties towards differently charged metal ions are investigated by ¹H NMR titration to obtain complexation constants (K _c -values for potassium/sodium rhodanides: 480–1100 mol dm⁻³), as well as extraction experiments to explore the metal ion transportation abilities of the new lariat crown derivatives. In particular, a significantly increased ability to transport metal ions from water into chloroform was found with spherical tetraoxaadamantyl derivatives when compared with the free amino-benzocrown ethers. Corresponding author. E-mail: kollenz@kfunigraz.ac.at Received July 5, 2002; accepted July 19, 2002