Synthesis and Properties of 2’-Deoxy-trans-3’,4’-BNA with S-Type Sugar Puckering

2'-deoxy-trans-3',4'-BNA monomer, which was previous synthesized as part of a study on bridged nucleic acids with S-type sugar puckering, was introduced into an oligodeoxynucleotide using phosphoramidite chemistry, and the hybridization ability of the 2'-deoxy-trans-3',4'-BNA-modified oligonucleotide with complementary DNA and RNA strands was evaluated. The 2'-deoxy-trans-3',4'-BNA-modified oligonucleotide showed greatly improved hybridization ability compared to its 2'-methoxy congener (2'-methoxy-trans-3',4'-BNA), which suggested that the sugar-restriction of nucleic acids to S-type conformation with appropriate design may be useful for development of DNA mimics.