Synthesis of nucleoside 5'-S-methylphosphonates and related compounds.

Phosphonate analogs of mono- and oligonucleotides with the P-C-O-C5' moiety have interesting biochemical and biophysical properties. A series of novel compounds, S-methylphosphonate-based nucleotides, with the P-C-S-C5' linkage was prepared as monomers for solid phase synthesis of modified oligonucleotides. Replacement of the 5'-oxygen atom with more nucleophilic, bulky, and lipophilic sulfur atom may influence the physicochemical and biological properties of nucleoside 5'-S-methylphosphonates and chimeric oligonucleotides as well.