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Modulární metodika na přípravu 3- a 4- substituovaných benzenových a anilínových C-ribonukleosidů
Štefko, Martin ; Hocek, Michal
A novel modular, efficient and practical methodology for the preparation of 3- and 4-substituted phenyl and aniline C-ribonucleosides was developed. The key intermediates were synthesized in two steps from TBS-protected ribonolactone in 75% and 66% yields, respectively, as pure beta-anomers. The bromophenyl intermediates were subjected to a series of palladium catalyzed cross-coupling, aminations and alkoxylation reactions to give, after deprotection a series of free 1 beta-(3- and 4-alkyl, -aryl, -amino -alkoxyphenyl and -hetaryl substituted phenyl)-C-ribonucleosides (20 examples).
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Modulární syntéza 5-substituovaných thiofen-2-yl C-2'-deoxyribonukleosidů
Bárta, Jan ; Hocek, Michal
A new modular methodology for the preparation of 5-substituted thiophen-2-yl C-nucleosides was developed. A Friedel–Crafts-type of C-glycosidation of 2-bromothiophene with bis-toluoyl protected methylglycoside gave the desired bis-toluoyl protected 1-beta-(5-bromothiophen-2-yl)-1,2-dideoxyribofuranose in 60%. Deprotection of the protected product gave free bromothiophene C-nucleoside, which was reprotected to bis-TBDMS protected C-nucleoside. The key intermediates were then subjected to a series of palladium catalyzed cross-coupling reactions to afford, after suitable deprotection, a series of free C-nucleosides. Alternatively, other types of C-nucleosides were prepared directly by aqueous-phase Suzuki cross-coupling reactions of free C-nucleosides with boronic acids.
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Modulární metodiky pro přípravu různých aryl C-2'-deoxyribonukleosidů
Joubert, Nicolas ; Bárta, Jan ; Urban, Milan ; Hocek, Michal
A modular methodology for the syntheses of various substituted aryl C-2´-deoxyribonucleosides has been developed. In each series, a larger scale synthesis of a versatile halogenated C-nucleoside intermediate has been accomplished, followed by its use for a generation of diverse derivatives by displacement of the halogen for alkyl, aryl or amino substituents by cross-coupling or amination reactions. Subsequent deprotection gave the final desired C-2´-deoxyribonucleosides. This methodology has been applied for the development of modular syntheses of 4- or 3-substituted benzene C-nucleosides, 6-substituted pyridin-2-yl C-nucleosides, 6-substituted pyridin-3-yl C-nucleosides and 5-substituted thiophen-2-yl C-nucleosides.
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