Nucleoside 3′-O-(2-Oxo-“Spiro”-4.4-Pentamethylene-1.3.2-Oxathiaphospholane)S: Monomers For Stereocontrolled Synthesis Of Oligo(Nucleoside Phosphorothioate/Phosphate)S

Abstract

Attempts at synthesis of “chimeric” oligonucleotide constructs (PO/PS-Oligos) possessing phosphate and P-stereodefined phosphorothioate internucleotide linkages via combined phosphoramidite/oxathiaphospholane methods were unsuccessful. Therefore, novel monomers for oxathiaphospholane method, namely 5′-O-DMT-deoxyribonucleoside 3′-O(2-oxo-.spiro-4.4-pentamethylene-1.3.2-oxathiaphospholane)s, were prepared and used together with their diastereomerically pure 2-thio analogues for the stereocontrolled synthesis of “chimeric” oligonucleotide constructs (PO/PS-Oligos).