Efficient oligonucleotide synthesis is the bottleneck behind many modern applications, from molecular diagnostics to nucleic acid therapeutics. The current workhorse approach—P(III)-phosphoramidite chemistry—delivers speed and reliability, yet it demands an oxidation step after nearly every nucleotide coupling cycle. That requirement adds reagents, increases exposure to moisture-sensitive intermediates, and slows automated workflows.
Pentavalent phosphorus (P(V)) chemistry has long been viewed as an alternative because it can, in principle, form nucleotide linkages without the repetitive oxidation routine. But earlier attempts struggled with practical chemistry: unstable intermediates, slow couplings, harsh deprotection conditions, and failures during chain elongation all prevented widespread replacement of P(III) strategies.
Now a team led by Associate Professor Noriko Saito-Tarashima at Tokushima University, working with doctoral researcher Nana Mihara, revisits the historical promise of P(V) chemistry using a modern design concept: stable nucleoside 3′-phosphorofluoridates (P(V)–F) as building blocks. Their study appears online on June 19, 2026, and is published in the Journal of the American Chemical Society (JACS), dated July 1, 2026.
The central idea is to remove oxidation from the cycle by using P(V)–F monomers that support neutral chain growth. This “oxidation-free” design targets three practical constraints at once: isolable, storage-stable monomers; coupling performance comparable to phosphoramidites; and reliable propagation of the growing oligonucleotide chain.
To make the approach work, the researchers activate the P(V)–F linkage with a silicon-based additive. By screening reaction bases and silicon-containing activators, they identify conditions that enable efficient dinucleotide formation. In a model system, the coupling yield reaches a quantitative level, indicating strong reactivity under synthetically practical conditions.
Speed matters as well: when benchmarked against standard P(III) phosphoramidite coupling, the P(V)–F system delivers faster assembly. That kinetic advantage suggests a path toward more efficient nucleotide cycles without sacrificing product quality.
Crucially, the method is not confined to solution-phase chemistry. The team adapts the P(V)–F coupling chemistry to automated solid-phase synthesis using a standard DNA/RNA synthesizer. Initial trials showed inconsistency, but targeted optimizations enabled successful automated oligonucleotide production—an essential step for real-world manufacturing.
Overall, the work positions P(V)–F as a complementary platform rather than a sudden replacement. By addressing oxidation overhead and improving robustness, the strategy could streamline the next generation of oligonucleotide manufacturing, accelerating research timelines and supporting future diagnostic and therapeutic pipelines.
Subject of Research: Oligonucleotide synthesis (chemical nucleic acid assembly)
Article Title: Nucleoside 3′-Phosphorofluoridates for P(V)-Based Oligonucleotide Synthesis
News Publication Date: 19-Jun-2026 (online availability); published 01-Jul-2026
Web References: https://pubs.acs.org/doi/10.1021/jacs.6c04623
References: DOI: 10.1021/jacs.6c04623
Image Credits: Credit: Associate Professor Noriko Saito-Tarashima from Tokushima University, Japan
Keywords: P(V) chemistry, oxidation-free synthesis, nucleoside 3′-phosphorofluoridates, oligonucleotides, silicon-mediated activation, automated solid-phase synthesis, phosphoramidite replacement, JACS
