Synthesis of a novel bridged nucleoside bearing a fused-azetidine ring, 3-amino-3,4-BNA monomer

Abstract A novel bridged nucleic acid monomer, 3′-amino-3′-deoxy-5-methyl-3′- N ,4′- C -methyleneuridine, was successfully synthesized via a useful and convenient azetidine ring formation under Staudinger's conditions. A 1 H NMR experiment and a PM3 calculation revealed that the sugar moiety of the novel bridged nucleic acid monomer, 3′-amino-3′,4′-BNA, was restricted to S-type conformation.