Modular H-Phosphonate Platform Opens New Route to Backbone-Modified Oligonucleotides
- Oligonucleotide backbone chemistry gets a new modular entry point: an H-phosphonate diester dinucleotide 'blockmer' platform that builds backbone-modified oligonucleotides through standard solid-phase synthesis.
- The method exploits the ambiphilic reactivity of H-phosphonate diesters, allowing diverse phosphate backbone modifications to be installed without air- or moisture-sensitive P(III) reagents or hazardous chemicals.
- Accessible backbone modifications span a wide range, from simple alkyl substitutions to sulfonamide-linked phosphate analogs, well beyond conventional phosphorothioate-type chemistries.
- Because the dinucleotide blockmers are compatible with existing solid-phase assembly workflows, they can be combined and positioned flexibly within a single oligonucleotide sequence.
- The platform is designed to enable systematic backbone structure-activity relationship studies in oligonucleotide drug discovery, providing a scalable and robust route for rapid analog generation.
H-phosphonate diesters as bench-stable P(III) surrogates is the headline: no more babysitting moisture-sensitive phosphitylating reagents under inert atmosphere just to install a novel backbone linkage. Backbone modification has been the stubborn bottleneck in oligo SAR — everyone can vary the sugar or the base, but stepping outside phosphorothioate/phosphorodiester space usually means bespoke phosphoramidite synthesis for every single analog. Pre-made dinucleotide blockmers flip that: build a small library of linkage types once, then mix-and-match them like ordinary phosphoramidites on standard solid-phase cycles, placing modifications at any position in the sequence. For a team running iterative backbone SAR, that's the difference between a multi-week custom-monomer detour and a same-week analog set. Real question is whether coupling efficiencies and diastereomer control hold up across the full modification set, not just the showcase examples.