Bis(O,O-diisopropoxy phosphinothioyl) disulfide - a highly efficient sulfurizing reagent for cost-effective synthesis of oligo(nucleoside phosphorothioate)s

A new sulfurizing reagent is reported for the automated synthesis of phosphothioate analogues of oligonucloetides via the phosphoramidite method. Bis(O,diisopropoxy phosphinothioyl) disulfide (S-Tetra, 1 ) is relatively inexpensive to prepare, easy to handle, and efficiently sulfurizes internucleotide phosphites, thus allowing the practical synthesis of oligo(nucleoside phosphorothioate)s with exceptionally high sulfur content.