A novel entry to 2′- O-aminopropyl modified nucleosides amenable for further modifications

A high yield sequence of Michael addition and Raney-Ni-reduction for 2′-RNA-modification. 2′- O-aminopropyl modified 4,6-difluoro-substituted benzimidazole nucleosides were synthesized in a two-step synthesis via Michael reaction and a Raney-nickel catalyzed reduction in high yields. These building blocks were used as a starting point for the conjugation of different carboxylic acids to enhance the lipophilicity or cationic character of oligonucleotides when used in biological assays or medical applications.