Abstract: A method is disclosed for preparing novel PNA synthons having protecting groups capable of removal under mild conditions. The PNA synthons are prepared by coupling novel N-substituted nucleobase intermediates having carbamate protection of the exocyclic amino group of the heterocycle to an amino protected backbone or an amino protected backbone ester of the amino acid N-(2-aminoethyl)-glycine. By the method of this invention, the resultant PNA synthons can have orthogonal protection of the carbamate protected nucleobase and the amino protected backbone. The PNA synthons are useful in the synthesis of peptide nucleic acids (PNAs) and other oligomers such as PNA-DNA chimeras, and may be used in automated synthesizers. Novel compositions of matter are also disclosed. In addition, a guanine PNA synthon having selective carbamate protection of the exocyclic 2-amino group with the C6 carbonyl group unprotected is disclosed.

Abstract: A method is disclosed for preparing novel purine PNA synthons having protecting groups which may be removed under mild conditions. The purine PNA synthons generally are prepared by coupling purine derivatives having carbamate protection to a protected N-(2-aminoethyl)-glycine backbone. By a method of this invention, purine PNA synthons may have orthogonal protection of the carbamate protected purine and the protected backbone. The purine PNA synthons are useful in the synthesis of peptide nucleic acids (PNAs) and other oligomers such as PNA-DNA chimeras, and may be used in automated synthesizers. In practicing methods of the invention, novel compositions of matter also are disclosed.