Enantiomeric Separation of 1-(Benzofuran-2-yl)alkylamines on Chiral Stationary Phases Based on Chiral Crown Ethers

Optically active chiral amines are important as building blocks for pharmaceuticals and as scaffolds for chiral ligands and, consequently, many efforts have been devoted to the development of efficient methods for their preparation. For example, reduction of amine precursors with chiral catalysts, 1 enzymatic kinetic resolution or dynamic kinetic resolution of racemic amines 2 and the direct amination of ketones with transaminases 3 have been developed as the efficient methods for the preparation of optically active chiral amines. During the process of developing or utilizing optically active chiral amines, the methods for the determination of their enantiomeric composition are essential. Among various methods, liquid chromatographic resolution of enantiomers on chiral stationary phases (CSPs) have been known to be one of the most accurate and economic means for the determination of the enantiomeric composition of optically active chiral compounds. 4 Especially, CSPs based on chiral crown ethers have been successfully used for the resolution of racemic primary amines. 5 For example, CSPs based on (+)-(18-crown-6)-2,3,11,12-tetracarboxylic acid