Utility of tetrathiomolybdate and tetraselenotungstate: efficient synthesis of cystine, selenocystine, and their higher homologues

Efficient synthesis of cystine, selenocystine, and their higher homologues like homo and bishomo amino acid derivatives from natural amino acid derivatives using tetrathiomolybdate and tetraselenotungstate reagents under mild and neutral conditions is reported. The generality of the reaction has been studied by capping various groups to amino and carboxyl components of canonical amino acids.