Water-soluble calix[4]resorcinarenes as chiral NMR solvating agents

ORGN 396

Kaitlin A Hagan, khagan@bates.edu, Department of Chemistry, Bates College, 5 Andrews Road, Lewiston, ME 04240 and Thomas J. Wenzel, twenzel@bates.edu, Chemistry, Bates College, Lewiston, ME 04240.
A series of hydroxylated prolinylmethyl derivatives of tetrasulfonated calix[4]resorcinarenes have been synthesized and their effectiveness as chiral NMR solvating agents for water-soluble aromatic-containing secondary amines examined. The aromatic substrates form host-guest complexes with the calix[4]resorcinarenes. The aromatic resonances of the substrates show large upfield shifts because of shielding from the aromatic rings of the calix[4]resorcinarenes. The H-1 NMR spectra of most substrates exhibit significant enantiomeric discrimination suitable for the determination of enantiomeric purity. The extent of enantiomeric discrimination depends on the interactions of the substrate with the proline moiety of the calix[4]resorcinarenes.