Oligoaminonucleoside phosphoramidates. Oligomerization of dimers of 3'-amino-3'-deoxy-nucleotides (GC and CG) in...

The self-complementary 5'-phosphorylated dinucleoside 3' (N)----5' (P)-linked phosphoramidates with sequence GC (8a), CG (8b) and the tetranucleoside triphosphoramidate with sequence GCGC (10a) and CGCG (10b) have been synthesized and characterized by physicochemical and enzymatic methods. The dinucleosides 8a or 8b oligomerize in aqueous solution in the presence of a water-soluble carbodiimide. This process is efficient and regiospecific. In the case of GC it produces alternating 3' (N)----5' (P)-linked phosphoramidates up to 15 dimeric units in length with a yield in excess of 70%. The oligomerization of the CG isomer is much less efficient. The mechanism of oligomerization is discussed.