We demonstrate the first use of Resonant Acoustic Mixing (RAM) without bulk solvent for the synthesis of short oligonucleotide fragments. Using the modified H-phosphonate approach, DNA, RNA, and 2′-modified nucleotides were successfully coupled to 3′-protected nucleosides in high yields (63–92%) while reducing solvent volume by 90%. In addition to synthesizing protected phosphodiester (PO) dimers and trimers, we also synthesized protected phosphorothioate (PS) dimers in good yields (63–65%). Using phosphoramidite chemistry, we were similarly able to reduce the solvent volume by 90% while coupling DNA phosphoramidites (58–92%) and RNA phosphoramidites (55–95%) with 3′-protected nucleosides in high yields followed by traditional oxidation with iodine in solution. Both strategies were successfully scaled up to multi-gram quantities which was facilitated by the use of RAM, offering the potential for larger scale-up, up to hundreds of kilograms continuously.

RSC Mechanochem., 2024,1, 244-249

5′-O-(2-Methoxyisopropyl) (MIP)-protected 2′-deoxynucleosides as chiral P(V)-building blocks, based on the limonene-derived oxathiaphospholane sulfide, were synthesized and used for the assembly of di-, tri-, and tetranucleotide phosphorothioates on a tetrapodal pentaerythritol-derived soluble support. The synthesis cycle consisted of two reactions and two precipitations: (1) the coupling under basic conditions, followed by neutralization and precipitation and (2) an acid catalyzed 5′-O-deacetalization, followed by neutralization and precipitation. The simple P(V) chemistry together with the facile 5′-O-MIP deprotection proved efficient in the liquid phase oligonucleotide synthesis (LPOS). Ammonolysis released nearly homogeneous Rp or Sp phosphorothioate diastereomers in ca. 80% yield/synthesis cycle.

J. Org. Chem. 2023, 88, 14, 10156–10163