title: Conjugation reactions involving maleimides and phosphorothioate oligonucleotides.
abstract: Phosphorothioate diester oligonucleotides proved to be fully compatible with maleimides in the context of two different conjugation reactions: (a) reaction of (5')diene-[phosphorothioate oligonucleotides] with maleimido-containing compounds to afford the Diels-Alder cycloadduct; (b) conjugation of (5')maleimido-[phosphorothioate oligonucleotides] with thiol-containing compounds. No evidence of reaction between phosphorothioate diesters and maleimides was found in any of these processes. Importantly, in the preparation of (5')maleimido-[phosphorothioate oligonucleotides] from [protected maleimido]-[phosphorothioate oligonucleotides], which requires the maleimide to be deprotected by retro-Diels-Alder reaction (heating for 3-4 h in toluene at 90 °C), no addition of phosphorothioate diester to the maleimide was found either. Finally, maleimide-[phosphorothioate monoester] conjugation was also explored for comparison purposes.
authors.affiliation: Departament de Química Orgànica and IBUB, Facultat de Química,  Universitat de Barcelona , Martí i Franquès 1-11, 08028 Barcelona, Spain.
authors.forename: Albert
authors.initials: A
authors.lastname: Sánchez
authors.forename: Enrique
authors.initials: E
authors.lastname: Pedroso
authors.forename: Anna
authors.initials: A
authors.lastname: Grandas
mesh_terms: D002851:Chromatography, High Pressure Liquid; D003500:Cyclization; D008301:Maleimides / Q000737:chemistry*; D015394:Molecular Structure; D054735:Phosphorothioate Oligonucleotides / Q000737:chemistry*
chemical_list: D008301:Maleimides; D054735:Phosphorothioate Oligonucleotides