A New Method for Removing Copper from Amino Acid-Copper Complexes by Sodium Thiosulfate

Sodium thiosulfate efficiently removed copper from amino acid-copper complexes. This new method was suitable for the synthesis of N-delta-benzyloxycarbonyl-L-ornithine, N-delta-tert-butyloxycarbonyl-L-ornithine, N-delta-fluorenylmethyloxycarbonyl-L-omithine, N-delta-acetyl-L-ornithine, N-delta-phthalyl-L-ornithine, N-delta-benzyloxycarbonyl-L-lysine, N-delta-tert-butyloxycarbonyl-L-lysine, N-delta-fluorenylmethyloxycarbonyl-L-lysine, N-delta-acetyl-L-lysine, N-delta-phthalyl-L-lysine, gamma-benzyl-glutamate, beta-benzyl-aspartate and their molecular structures were confirmed by elemental analysis and H-1 NMR. The effects of reaction temperature, time, materials proportion and solvent on copper-removing reaction were studied. It was shown that when N-delta-protective ornithine copper complexes and sodium thiosulfate were reacted with the molar ratio of 1 : 1 or 1: 2 at 60 degrees C for 1.5 similar to 2.0 h, the product yield and purity were high. The method is rapid, convenient in operation and environment friendly.