Synthesis and incorporation of methyleneoxy(methylimino) linked thymidine dimer into antisense oligonucleosides

A convenient synthesis of a thymidine (T) nucleoside dimer (T-3′-CH₂-O-NCH₃-5′-T) 12 has been accomplished via a nucleoside coupling reaction. An alternative synthesis of 3′-deoxy-3′-C-hydroxymethylthymidine is described. The new dimer and methodology is useful for the development of backbone-modified antisense oligonucleosides.