title: 31P NMR study of the desulfurization of oligonucleoside phosphorothioates effected by "aged" trichloroacetic acid solutions.
abstract: When employing phosphoramidites 1a-d in the solid-phase synthesis of oligonucleoside phosphorothioates, the thermolytic 2-[N-methyl-N-(2-pyridyl)]aminoethyl thiophosphate protecting group is lost to a large extent during the course of the synthesis. The resulting phosphorothioate diesters are then substantially desulfurized upon recurring exposure to a commercial solution of deblocking reagent during chain assembly. This problem is caused by the secondary decomposition product(s) of the reagent and is alleviated by using a fresh solution of the deblocking reagent prepared from solid trichloroacetic acid.
authors.affiliation: Division of Therapeutic Proteins, Center for Drug Evaluation and Research, Food and Drug Administration/NIH, 8800 Rockville Pike, Bethesda, MD 20892, USA.
authors.forename: Jacek
authors.initials: J
authors.lastname: Cieślak
authors.forename: Cristina
authors.initials: C
authors.lastname: Ausín
authors.forename: Marcin K
authors.initials: MK
authors.lastname: Chmielewski
authors.forename: Jon S
authors.initials: JS
authors.lastname: Kauffman
authors.forename: John
authors.initials: J
authors.lastname: Snyder
authors.forename: Alfred
authors.initials: A
authors.lastname: Del-Grosso
authors.forename: Serge L
authors.initials: SL
authors.lastname: Beaucage
mesh_terms: D001483:Base Sequence; D009682:Magnetic Resonance Spectroscopy; D015394:Molecular Structure; D009838:Oligodeoxyribonucleotides / Q000138:chemical synthesis* / Q000737:chemistry; D010755:Organophosphates / Q000737:chemistry*; D010710:Phosphates / Q000737:chemistry; D010759:Phosphorus Isotopes; D013455:Sulfur / Q000737:chemistry; D013873:Thionucleotides / Q000737:chemistry; D014238:Trichloroacetic Acid / Q000737:chemistry
chemical_list: D009838:Oligodeoxyribonucleotides; D010755:Organophosphates; D010710:Phosphates; D010759:Phosphorus Isotopes; D013873:Thionucleotides; D014238:Trichloroacetic Acid; D013455:Sulfur