Nucleoside-O-(2-thiono-1,3,2-oxathiaphospholane)S-versatile tools in the synthesis of oligonucleotide analogues

The scope and limitations of 1,3,2-oxathiaphospholane ring opening condensa tion process are discussed with the emphasis paid to internucleotide bond f ormation and stereocontrolled synthesis of P-chiral phosphorothioate analog ues of oligonucleotides.