Novel methods for the preparation of monomethoxytrityl (Mmt) protected aminoethylglycine building blocks and dimethoxytrityl (Dmt) protected hydroxyethylglycine derivatives useful for the synthesis of polyamide nucleic acids (PNAs) and PNA/DNA chimeras are described. The protecting group strategy employed for PNA monomer synthesis produces easily isolable intermediates, minimizes chromatographic purification, and is suitable for large-scale monomer synthesis. (C) 1997 Elsevier Science Ltd.