A NEW APPROACH TO OLIGONUCLEOTIDE N3′⇉P5′ PHOSPHORAMIDATE BUILDING BLOCKS

A new synthetic approach to 5′-phosphoramidites of 3′-aminonucleosides was developed. The methodology relies upon the use of 3′-amino-2′,3′-dideoxy nucleosides as the key starting materials. The final phosphoramidite products were obtained with high yields via 2–3-step efficient chemical transformations using selective introduction of orthogonal protective groups to the 3′-aminonucleoside sugar and base moieties.