DNA and RNA phosphorothioates have attracted attention as novel therapeutic agents through antisense mechanism of action and because of their nuclease resistance.
1) Beaucage reagent (
1),
2) bis(phenylacetyl) disulfide (
2)
3) and
xanthane hydride (
3)
4,5) are widely used as sulfur-transfer reagents for the synthesis of oligonucleotide phosphorothioates via the phosphoramidite method. In particular,
3 has the advantages that it does not yield oxidants leading to side reactions and generating toxic substances such as carbon disulfide or cyanamide, as byproducts.