Phosphorylating reagent-free synthesis of 5'-phosphate oligonucleotides by controlled oxidative degradation of their 5'-end

The 5'-phosphorylated oligonucleotides (5'-pONs) are currently synthesized using expensive and sensitive modified phosphoramidite reagents. In this work, a simple, cost-effective, efficient, and automatable method is presented, based on the controlled oxidation of the 5'-terminal alcohol followed by a β-elimination reaction. The latter reaction leads to the removal of the terminal 5'-nucleoside and subsequent formation of the 5'-phosphate moiety. Thus, chemical phosphorylation of oligonucleotides (DNA or RNA) is achieved without using modified phosphoramidites.