A convenient synthesis of a thymidine (T) nucleoside dimer (T-3'-CH2-O-NCH3-CH2-4'-T) 12 has been accomplished via a nucleoside coupling reaction. An alternative synthesis of 3'-deoxy-3'-C-hydroxymethyl-thymidine is described. The new dimer and methodology is useful for the development of backbone-modified antisense oligonucleosides.