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Abstract l ‐Selenocystine ( 5 ) and l ‐tellurocystine ( 6 ) have been prepared and the reactivity of these amino acids, i.e., oxidation of 5 and 6 , has been performed at various pH values. Hydrogen peroxide was used as an oxidant and it was treated with 5 and 6 in excess in acidic and basic media. Compound 5 , upon oxidation, afforded Se IV and Se VI products. Selenocysteic acid HO 3 SeCH 2 CH(NH 2 )COOH 9 , a novel Se VI compound, was isolated and characterised by single‐crystal X‐ray diffraction studies. In contrast, l ‐tellurocystine, upon oxidation with H 2 O 2 , afforded Te II and Te IV products. Zwitterionic organotellurolate(IV), TeCl 3 CH 2 CH(NH 3 )COOH 13 , was isolated and characterised by NMR and IR spectroscopy, mass spectrometry and elemental analysis. Compound 13 crystallizes in an orthorhombic space group. l ‐Tellurocystine, when reduced with NaBH 4 , produced the desired tellurolate intermediate, which was trapped with bromoacetic acid. Furthermore, l ‐ and d ‐tellurocysteine derivatives, (RTeCH 2 CH(NH 2 )COOH) R=phenyl, substituted phenyl and naphthyl ( 24 – 39 ) were synthesised and evaluated for their glutathione peroxidase (GPx)‐like activities. The results show that l ‐tellurocysteine derivatives have higher activity than their D ‐tellurocysteine analogues. DFT calculations for l ‐tellurocysteine derivatives provided information about the bond lengths and bond angles. This study reveals that the introduction of naphthyl substituents ( 35 – 38 ) leads to twisted conformation of the amino acid derivatives.
Satheeshkumar et al. (Tue,) studied this question.