title: Liquid-Phase Synthesis of 2'-Methyl-RNA on a Homostar Support through Organic-Solvent Nanofiltration.
abstract: Due to the discovery of RNAi, oligonucleotides (oligos) have re-emerged as a major pharmaceutical target that may soon be required in ton quantities. However, it is questionable whether solid-phase oligo synthesis (SPOS) methods can provide a scalable synthesis. Liquid-phase oligo synthesis (LPOS) is intrinsically scalable and amenable to standard industrial batch synthesis techniques. However, most reported LPOS strategies rely upon at least one precipitation per chain extension cycle to separate the growing oligonucleotide from reaction debris. Precipitation can be difficult to develop and control on an industrial scale and, because many precipitations would be required to prepare a therapeutic oligonucleotide, we contend that this approach is not viable for large-scale industrial preparation. We are developing an LPOS synthetic strategy for 2'-methyl RNA phosphorothioate that is more amenable to standard batch production techniques, using organic solvent nanofiltration (OSN) as the critical scalable separation technology. We report the first LPOS-OSN preparation of a 2'-Me RNA phosphorothioate 9-mer, using commercial phosphoramidite monomers, and monitoring all reactions by HPLC, (31)P NMR spectroscopy and MS.
authors.affiliation: Department of Chemical Engineering, Imperial College, South Kensington Campus, London, SW7 2AZ (UK).
authors.forename: Piers R J
authors.initials: PR
authors.lastname: Gaffney
authors.affiliation: Department of Chemical Engineering, Imperial College, South Kensington Campus, London, SW7 2AZ (UK).
authors.forename: Jeong F
authors.initials: JF
authors.lastname: Kim
authors.affiliation: Department of Chemical Engineering, Imperial College, South Kensington Campus, London, SW7 2AZ (UK).
authors.forename: Irina B
authors.initials: IB
authors.lastname: Valtcheva
authors.affiliation: GSK Medicines Research Centre, Gunnels Wood Road, Stevenage, Herts, SG1 2NY (UK).
authors.forename: Glynn D
authors.initials: GD
authors.lastname: Williams
authors.affiliation: GSK Medicines Research Centre, Gunnels Wood Road, Stevenage, Herts, SG1 2NY (UK).
authors.forename: Mike S
authors.initials: MS
authors.lastname: Anson
authors.affiliation: GSK Medicines Research Centre, Gunnels Wood Road, Stevenage, Herts, SG1 2NY (UK).
authors.forename: Andrew M
authors.initials: AM
authors.lastname: Buswell
authors.affiliation: Department of Chemical Engineering, Imperial College, South Kensington Campus, London, SW7 2AZ (UK). a.livingston@imperial.ac.uk.
authors.forename: Andrew G
authors.initials: AG
authors.lastname: Livingston
mesh_terms: D002851:Chromatography, High Pressure Liquid; D009682:Magnetic Resonance Spectroscopy; D009841:Oligonucleotides / Q000737:chemistry*; D009930:Organic Chemicals; D009943:Organophosphorus Compounds / Q000737:chemistry*; D012313:RNA / Q000138:chemical synthesis* / Q000737:chemistry; D060327:Solid-Phase Synthesis Techniques; D012997:Solvents / Q000737:chemistry
chemical_list: D009841:Oligonucleotides; D009930:Organic Chemicals; D009943:Organophosphorus Compounds; D012997:Solvents; C434331:phosphoramidite; D012313:RNA
keywords: RNA; homostar; liquid-phase synthesis; nanofiltration; nucleic acids; solid-phase synthesis