Azide phosphoramidite in direct synthesis of azide-modified oligonucleotides.

Azide and phosphoramidite functions were found to be compatible within one molecule and stable for months in solution kept frozen at -20 °C. An azide-carrying phosphoramidite was used for direct introduction of multiple azide modifications into synthetic oligonucleotides. A series of azide-containing oligonucleotides were modified further using click reactions with alkynes.