| Abstract: | Normal phase high-performance liquid chromatography has been achieved of the common activated forms of valine on a LiChrosorb-CN or a μPorasil (underivatized silica) column using hexane containing 1.5 or 5%tert.-butanol as solvent. Compounds examined include the 2-alkoxy-5(4H)-oxazolones and symmetrical and mixed anhydrides of N-tert.-butoxycarbonyl-, N-benzyloxycarbonyl-, and N-9-fluorenylmethoxycar-bonylvaline, the chloride of the latter, a p-nitrophenyl ester, 2-methyl-4-isopropyl-5(4H)-oxazolone, valine-N-carboxyanhydride, and the N- and O-ethoxycarbonyl adducts of 1-hydroxybenzotriazole. The 5(4H)-ox-azolones from N-tert.-butoxycarbonylvaline and N-benzyloxycarbonylglycylvaline decomposed during chromatography on the μPorasil but not the LiChrosorb-CN column. The method allows direct monitoring of reactions involving generation or consumption of activated forms of amino acids. |
