Peptide nucleic acids are the potential candiated of antisense and anitgene. Chiral monomer backbones were efficiently prepared by reductive amination of N-Boc or N-Fmoc protected L alaninal with aminomethylphosphate diethyl ester and subsequent acylation of free secondary amines with thymine-1-ylacetic acid. After chemical swith of N-Boc to N-Fmoc, protected chiral phosphono-PNA monomers were obtained.

Key words: NUCLEIC ACIDS, REDUCTION, AMMONIATION, CONDENSATION