Synthesis of threose nucleic acid (TNA) phosphoramidite monomers and oligonucleotide polymers

This unit describes the preparation of dimethoxytrityl (DMTr)-protected α-L-threofuranosyl nucleic acid (TNA) phosphoramidite monomers for A, C, G, T, and diaminopurine, as well as their incorporation into TNA oligonucleotides by solid-phase synthesis. Starting from commercially available L-ascorbic acid, the protected threofuranosyl sugar is obtained in four steps. Vorbrüggen-Hilbert-Johnson glycosylation affords the desired threofuranosyl nucleosides, which are converted to their corresponding DMTr-protected phosphoramidite nucleosides in four additional steps. Phosphoramidite monomers are then used to construct TNA oligonucleotides by solid-phase synthesis using a standard DNA synthesizer.