US Patent 7253299 Process for purifying n2-(1(s)-ethoxycarbonyl-3-phenylpropyl)-n6-thifluoroacetyl-l-lysine

A process for purifying N2-(1(S)-ethoxycarbonyl-3-phenylpropyl)-N6-trifluoroacetyl-L-lysine which comprises subjecting N2-(1(S)-ethoxycarbonyl-3-phenylpropyl)-N6-trifluoroacetyl-L-lysine contaminated with impurities to crystallization from a solvent comprising a water-soluble non-protic organic solvent, thereby removing the impurities into the mother liquor and giving crystals of N2-(1(S)-ethoxycarbonyl-3-phenylpropyl)-N6-trifluoroacetyl-L-lysine, according to which N2-(1(S)-ethoxycarbonyl-3-phenylpropyl)-N6-trifluoroacetyl-L-lysine having a high quality can be obtained in a high yield and a high productivity and which is suitable for practice on an industrial scale.