Chiral Stationary Phase Derived from (-)-anti Head-to-Head Coumarin Dimer: Preparation, Characterization, and Chiral Recognition Ability

Article abstract of DOI:10.1246/bcsj.65.3423

A monoamide derived from (-)-anti head-to-head coumarin dimer <(-)-CD> with propylamine has been successfully bonded to silica gel (Lichrospher 100 NH2: Merck) through amide linkage to prepare CSP-1.Another monoamide derivative CSP-2 was prepared by direct nucleophilic opening of one lactone ring of (-)-CD by Lichospher 100 NH2, followed by hydrolysis of the other lactone.CSP-1 and CSP-2 showed high enantioselectivity to trans-stilbene oxide with separation factors (α) at 2.42 and 2.46, respectively, and the (-)-isomer eluted first.The capacity factor (k') and α decrease with increasing polarity of the eluent (hexane/2-propanol), indicating that hydrogen bonding plays important role in chiral recognition.CSP-3, obtained by ligand exchange of CSP-2 with CuSO4_(aq), resolved DL-tryptophan, DL-tyrosine, and DL-phenylalanine (α = k_D'/K_L' = 1.14-1.33), which all contain aromatic chromophore.The stability difference of the ternary complexes formed with D-isomer and L-isomer is explained by steric hindrance and aromatic ?-? interactions.