N-pent-4-enoyl (PNT) group as a universal nucleobase protector: Applications in the rapid and facile synthesis of oligonucleotides, analogs, and conjugates

Rapid synthesis of phosphoric diester and phosphorothioate oligonucleotides in 1 micromol to 1 millimol scale has been achieved using PNT nucleoside phosphoramidites. Furthermore, facile synthesis of mixed backbone oligonucleotides (MBOs) as antisense agents can be carried out using PNT nucleoside phosphoramidites in conjunction with PNT nucleoside H-phosphonates and PNT nucleoside phosphonamidites. The versatility of the PNT group is further demonstrated by its use in the preparation of bioreversible oligonucleotide conjugates. (C) 1997 Elsevier Science Ltd.