Azidomethyl-ruthenocene: facile synthesis of a useful metallocene derivative and its application in the 'click' labelling of biomolecules.

A convenient synthesis of azidomethyl-ruthenocene and its use in the covalent labelling of amino acids, peptides and a peptide nucleic acid (PNA) monomer derivative by Cu(I) catalyzed azide-alkyne coupling (Cu-AAC, "click chemistry") are described.