Journal: Organic Process Research & Development
Article Title: Scalable Membrane Enabled One-Pot Liquid-Phase Oligonucleotide Synthesis
doi: 10.1021/acs.oprd.5c00117
Figure Lengend Snippet: Schematic representation of the overall process developed. One-pot LPOS chain extension conditions per arm: (i) Coupling: 2’-OMe phosphoramidite (1.5 equiv), DCI (4 equiv), 10% w/v 3 Å molecular sieves, MeCN, RT, 30–60 min; amidite quench: MeOH (5 equiv); (ii) sulfurization: PADS (9 equiv) or POS (3 equiv), MeCN, RT, 60 min; (iii) detritylation: TFA (15–180 equiv) and CySH (5–15 equiv), MeCN:DCM (2:1 v/v), 0 °C, 30–130 min; acid quench: pyridine (20–185 equiv), MeCN:DCM (2:1 v/v), 0 °C, 10 min; (iv) diafiltration purification using ceramic OSN/OSU membrane. Cycle is repeated n times until desired sequence is reached. [Me: methyl, Dmtr: dimethoxytrityl, ib: isobutyryl, bz: benzoyl, ac: acetyl, Cne: cyanoethyl, iPr: isopropyl].
Article Snippet: To compare to other LPOS strategies, we evaluated two methods: the kilogram scale convergent LPOS precipitation approach by Zhou et al. at Biogen, which had a PMI ∼ 63 kg/kg, and the membrane-based nanostar sieving approach by Kim et al. from the Livingston group, which had a PMI ∼ 2480 kg/kg., , , For our developed OP-LPOS via UF membrane process, the PMI was estimated for producing 1 kg of a 20-mer PS 2′-OMe oligonucleotide based upon average values obtained experimentally (filtration yield of 99.6%, coupling efficiency of 98%, filtration and reaction conc. of 1% w/v and 12% w/v respectively, 5 diavolumes to purity and 2 diavolumes to collect) and input into the ACS Green Chemistry PMI calculator.
Techniques: Diafiltration Assay, Purification, Membrane, Sequencing