title: Stereoselective synthesis of alkynyl C-2-deoxy-beta-d-ribofuranosides via intramolecular nicholas reaction: A versatile building block for nonnatural C-nucleosides.
abstract: The reaction of 3,5-di-O-benzyl-2-deoxy-d-ribofuranose with various alkynyllithium reagents afforded diastereomeric mixtures of the corresponding ring-opened alkynyldiols. The resulting diastereomeric mixtures were successively treated with Co(2)(CO)(8), a catalytic amount of TfOH, Et(3)N, and iodine in one pot to give alkynyl C-3,5-di-O-benzyl-2-deoxy-beta-d-ribofuranosides with high beta-selectivities. The cobalt-mediated cyclization (intramolecular Nicholas reaction) is reversible; thus, thermodynamically more stable beta-anomers were obtained preferentially. The alkynyl C-deoxyribofuranosides were converted to a variety of C-deoxyribofuranoside derivatives.
authors.affiliation: PRESTO, Japan Science and Technology Corporation (JST), Faculty of Pharmaceutical Sciences, Toyama Medical and Pharmaceutical University, Toyama 930-0194, Japan.
authors.forename: Masayoshi
authors.initials: M
authors.lastname: Takase
authors.forename: Tomoyuki
authors.initials: T
authors.lastname: Morikawa
authors.forename: Hajime
authors.initials: H
authors.lastname: Abe
authors.forename: Masahiko
authors.initials: M
authors.lastname: Inouye
mesh_terms: D000480:Alkynes / Q000138:chemical synthesis*; D003500:Cyclization; D003853:Deoxyribonucleosides / Q000138:chemical synthesis* / Q000737:chemistry; D007202:Indicators and Reagents; D013237:Stereoisomerism
chemical_list: D000480:Alkynes; D003853:Deoxyribonucleosides; D007202:Indicators and Reagents