Use of Phenylacetyl Disulfide (PADS) in the Synthesis of Oligodeoxyribonucleotide Phosphorothioates

Abstract

Oligodeoxyribonucleotide phosphorothioates, where one of the nonbridging oxygen of the internucleotide phosphate is formally replaced by a sulfur atom, are the first class to undergo human clinical trials. Ongoing phosphorothioate clinical trials against several disease targets has necessitated manufacture of very large quantities of oligonucleotide active pharmaceutical ingredient (API). Clinical trial and future market demands have stimulated effort towards developing cost efficient large scale synthesis of these complex bio-molecules. This effort has culminated in the routine synthesis of 20-mer oligodeoxyribonucleotide phosphorothioates at 150 mmole scale using only 1.75-fold molar excess of amidites in less than 8 h total synthesis time.