The precursor strategy: terminus methoxyoxalamido modifiers for single and multiple functionalization of oligodeoxyribonucleotides

Synthesis of new terminus modifiers, bearing, along with a phosphoramidite moiety, one, two or four methoxyoxalamido (MOX) precursor groups, is described. These modifiers are introduced onto the 5′-end of a synthetic oligodeoxyribonucleotide as the last step of an automated synthesis to form the MOX precursor oligonucleotide. The MOX groups are then post-synthetically derivatized with an appropriate primary amine to construct a 5′-modified oligonucleotide. The efficiency and simplicity of the novel modifying strategy were demonstrated in the synthesis of a number of 5′-functionalized oligonucleotides.