Synthesis of azophenolic crown ethers of Cs symmetry incorporating cis-1-phenylcyclohexane-1,2-diol residues as a steric barrier and diastereotopic face selectivity in complexation of amines by their diastereotopic faces

Abstract

Azophenolic crown ethers 1 and 2 of C_s symmetry incorporating cis-1-phenylcyclohexane-1,2-diol residues as a steric barrier have been prepared. Diastereotopic face selectivity in complexation with 2-methoxyethylamine, n-propylamine and ethanolamine was examined using temperature-dependent ¹H NMR spectroscopy. Both bind ethanolamine stereoselectively to one of their diastereotopic faces; the prediction of which diastereoisomeric complex was preferentially formed is made on the basis of a CPK molecular-model examination of the complexes.