[Separation of 3-substituted-(R,S)-beta-alanine derivatives by high performance liquid chromatography].

ABSTRACT

3-Substituted-(R,S)-beta-alanines derivatized by 1-fluoro-2,4-dinitro-5-L-valinamide (Marfey's reagent) were successfully separated by reversed-phase high performance liquid chromatography. The separations were performed with gradient elution. The mobile phase A was acetonitrile containing 0.1% (v/v) trifluoroacetic acid and the mobile phase B was 0.1% (v/v) trifluoroacetic acid aqueous solution. Thirty-two pairs of 3-substituted-(R,S)-beta-alanine derivatives, phenyl, substituted phenyl, naphthyl, substituted pyridyl and thienyl, were separated. The mobile phase A content was changed from 35% to 75% in 20 min. All (R-L)-diastereomers were eluted prior to the (S-L) ones. Substituents with larger hydrophobic parameters (pi) gave longer retention times (tR) for their derivatives than those with smaller ones except for 3-hydroxyphenyl and 4-hydroxyphenyl substituents. The positioning of the substituents on benzene ring of beta-alanines (beta-Ala) also influenced tR and separation. 4-Subsituted-phenyl-(R,S)-beta-Ala derivatives gave longer tR and better separation than 2-substituted isomers. The enantiomer excess values of R- and S-beta-Ala were also determined.