Application of the click reaction for coupling a 2-(2-aminoethoxy) ethoxy (AEE) function to thyminyl, cytosinyl and adeninyl peptide nucleic acid (PNA) monomer analogues bearing a N-propynyl group, in place of the original N-2-aminoethyl moiety, has been explored. The N- propynyl PNA analogues were prepared from glycine ethyl ester hydrochloride and the structure of the thyminyl derivative was confirmed by X-ray diffraction. These monomers ...