Stereoselective synthesis of alkynyl C-2-deoxy-beta-d-ribofuranosides via intramolecular nicholas reaction: A versatile building block for nonnatural C-nucleosides.
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.
Takase
Masayoshi
M
PRESTO, Japan Science and Technology Corporation (JST), Faculty of Pharmaceutical Sciences, Toyama Medical and Pharmaceutical University, Toyama 930-0194, Japan.
Morikawa
Tomoyuki
T
Abe
Hajime
H
Inouye
Masahiko
M
D000480:Alkynes / Q000138:chemical synthesis*; D003500:Cyclization; D003853:Deoxyribonucleosides / Q000138:chemical synthesis* / Q000737:chemistry; D007202:Indicators and Reagents; D013237:Stereoisomerism
D000480:Alkynes; D003853:Deoxyribonucleosides; D007202:Indicators and Reagents