Design and synthesis of new chiral calix[4]arenes as liquid phase extraction agents for α-amino acid methylesters and chiral α-amines

The article describes the synthesis and extraction properties of new (S)(-)-1-phenylethylamine substituted p-tert-butylcalix[4]arene/calix[4]arene. These compounds have been synthesized via nucleophilic substitution reactions involving 5,11,17,2 3-tetra-tert-butyl-25,26,27,28-tetra(2-hydroxyethoxy)calix[4]arene (4a), or 5,11,17,23-tetra-H-25,26,27,28-tetra(2-hydroxyethoxy)calix[4]arene (4b) with (S)(-)-1-phenylethylamine in dry THF. The extraction properties of ligands 5a and 5b towards the some selected alpha-amino acid methylesters and chiral alpha-amines are also reported. It has been observed that receptor 5a was an excellent ionophore for alpha-amino acid methylesters/alpha-amines and good extractant than 5b. However, both of the ligands did not display any selectivity towards the configurations of this species.