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Development of a general and modular approach to C-nucleosides
Kubelka, Tomáš ; Štefko, Martin ; Bárta, Jan ; Joubert, Nicolas ; Urban, Milan ; Chapuis, Hubert Jean ; Hocek, Michal
Highly efficient and modular approach was developed for the synthesis of various types of new (het)aryl C-nucleosides. This protocol consists of the synthesis of haloaryl-C-nucleoside intermediates, followed by a functional group transformation to introduce various substituents. Using this approach protected 2′-deoxy-C-nucleosides bearing halogenated benzene, pyridine, thiophene, furane and pyrimidine were prepared. These intermediates were then submitted to a wide range of palladium-catalyzed reactions. The same approach was also used for preparation of C-nucleosides bearing ribofuranose moiety. Functional ribofuranosides bearing diverse substituted pyridine and benzene nucleobases were prepared in this way.
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Syntéza (purin-6-yl)acetátů a jejich transformace
Hasník, Zbyněk ; Hocek, Michal
A novel approach to the synthesis of (purin-6-yl)acetates was developed based on Pd-catalysed cross-coupling reactions of 6-chloropurines with the Reformatsky agent. These intermediates were converted into various products by functional group transformations. Amides were prepared by amidation of ester group with amines, 6-(hydroxyethyl)purines by reduction by NaBH4, and beta-substituted 6-ethylpurines by mesylation of 6-(hydroxyethyl)purines and subsequent nucleophilic substitution.
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Přímá C-H arylace purinů a purinových nukleosidů
Čerňa, Igor ; Hocek, Michal
Direct C–H arylation of purines to position 8 by diverse aryl halides was achieved using Pd catalysis in the presence of CuI and Cs2CO3. The methodology was applied in consecutive regioselective synthesis of 2,6,8-trisubstituted purines bearing three different C-substituents in combination with two cross-coupling reaction. In addition, direct arylation of unprotected purine nucleosides with aryl iodides at position 8 was developed to allow straightforward single-step introduction of diverse aryl groups.
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