Enantiomeric Resolution of α-Amino Acid Derivatives on Two Diastereomeric Chiral Stationary Phases Based on Chiral Crown Ethers Incorporating Two Different Chiral Units

Abstract

Two diastereomeric chiral stationary phases (CSPs) were applied to the liquid chromatographic resolution of various racemic α-amino methyl esters, α-amino N,N-diethylamides and α-amino N-propylamides. The CSP incorporating (R)-3,3'-diphenyl-1,1'-binaphtyl and (R,R)-tartaric acid unit as chiral barriers did not show any chiral recognition. In contrast, the CSP incorporating (R)-3,3'-diphenyl-1,1'-binaphtyl and (S,S)-tartaric acid unit as chiral barriers was found to show excellent chiral recognition especially for the two enantiomers of α-amino N-propylamides. Some of α-amino methyl esters and α-amino N,N-diethylamides were also resolved on the CSP incorporating (R)-3,3'-diphenyl-1,1'-binaphtyl and (S,S)-tartaric acid unit. From these results it was concluded that the two chiral units composing the diastereomeric CSPs can show matched or mismatched effect on the chiral recognition according to their absolute stereochemistry.