Synthesis and duplex-forming ability of oligonucleotides modified with 4'-C,5'-C-methylene-bridged nucleic acid (4',5'-BNA).

Abstract We describe herein the design and synthesis of 4′-C,5′-C-methylene-bridged nucleic acid (4′,5′-BNA), a novel artificial nucleic acid with the torsion angle γ in a non-canonical +ac range. The 4′,5′-BNA phosphoramidite bearing a thymine nucleobase was synthesized from a commercially available thymidine analog in 11 steps and successfully incorporated into oligonucleotides. The resulting oligonucleotides were evaluated for their duplex-forming ability toward single-stranded DNA and RNA.