title: Towards the synthesis of inosine building blocks for the preparation of oligonucleotides with hydrophobic alkyl chains between the nucleotide units.
abstract: The scientific objective of the research reported in this manuscript was the synthesis of novel phosphoramidite building blocks for the preparation of lipophilic oligonucleotides. Reaction of inosine (4) with 4-oxopentyl-4-methylbenzoate (2c) in the presence of triethyl orthoformate and 4M HCl in 1,4-dioxane gave a diastereoisomeric mixture of the ketals 5. Subsequent 4,4'-dimethoxytritylation at the 5'-hydroxyl afforded (R)-6 + (S)-6 which could be separated chromatographically. Detoluoylation gave compounds (R)-7 and (S)-7. Phosphitylation of a diastereoisomeric mixture of 7 led to a mixture of four diastereoisomers of the corresponding 2-cyanoethylphosphoramidites 8.
authors.affiliation: Organische Materialchemie und Bioorganische Chemie, Institut für Chemie, Fachbereich Biologie/Chemie, Universität Osnabrück, Osnabrück, Germany.
authors.forename: Karl
authors.initials: K
authors.lastname: Köstler
authors.forename: Helmut
authors.initials: H
authors.lastname: Rosemeyer
mesh_terms: D000577:Amides / Q000737:chemistry*; D006851:Hydrochloric Acid / Q000737:chemistry; D007288:Inosine / Q000138:chemical synthesis* / Q000737:chemistry*; D008956:Models, Chemical; D015394:Molecular Structure; D009841:Oligonucleotides / Q000138:chemical synthesis* / Q000737:chemistry*; D009943:Organophosphorus Compounds / Q000138:chemical synthesis* / Q000737:chemistry*; D010756:Phosphoric Acids / Q000737:chemistry*; D013237:Stereoisomerism
chemical_list: D000577:Amides; D009841:Oligonucleotides; D009943:Organophosphorus Compounds; D010756:Phosphoric Acids; D007288:Inosine; C011067:phosphoramidic acid; D006851:Hydrochloric Acid