title: A simple procedure for the preparation of protected 2'-O-methyl or 2'-O-ethyl ribonucleoside-3'-O-phosphoramidites.
abstract: Protected 2'-O-methyl and 2'-O-ethyl ribonucleoside-3'-O-phosphoramidites were prepared via alkylation of the ribonucleosides at an early stage in the synthesis. Utilizing a strategy of minimal protection, the alkylation was performed with unprotected cytidine and adenosine, or with O6-protected guanosine and N3,5'-O-protected uridine using methyl or ethyl iodide and sodium hydride. In subsequent steps, the introduction of standard protective groups for oligonucleotide synthesis and the concomitant separation from 3'-O-alkylated isomers was accomplished. A modification of the phosphitylation procedure permitted facile isolation of the desired phosphoramidites which show high coupling efficiencies in oligomer assembly.
authors.affiliation: Institute for Molecular Pathology, Vienna, Austria.
authors.forename: E
authors.initials: E
authors.lastname: Wagner
authors.forename: B
authors.initials: B
authors.lastname: Oberhauser
authors.forename: A
authors.initials: A
authors.lastname: Holzner
authors.forename: H
authors.initials: H
authors.lastname: Brunar
authors.forename: G
authors.initials: G
authors.lastname: Issakides
authors.forename: G
authors.initials: G
authors.lastname: Schaffner
authors.forename: M
authors.initials: M
authors.lastname: Cotten
authors.forename: M
authors.initials: M
authors.lastname: Knollmüller
authors.forename: C R
authors.initials: CR
authors.lastname: Noe
mesh_terms: D004980:Ethane / Q000737:chemistry; D007455:Iodine; D009682:Magnetic Resonance Spectroscopy; D008697:Methane / Q000737:chemistry; D008745:Methylation; D009841:Oligonucleotides / Q000138:chemical synthesis*; D009943:Organophosphorus Compounds / Q000138:chemical synthesis*; D012263:Ribonucleosides / Q000138:chemical synthesis*
chemical_list: D009841:Oligonucleotides; D009943:Organophosphorus Compounds; D012263:Ribonucleosides; D007455:Iodine; D004980:Ethane; D008697:Methane