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Dichotomy in regioselectivity of Pd-catalyzed direct C-H arylation of protected uracils
Čerňová, Miroslava ; Hocek, Michal
Uracil bases and nucleosides bearing aryl groups in positions 5 or 6 are an important class of compounds and display wide range of biological activities1. In addition, arylation in position 5 is often used for labeling of nucleotides, oligonucleotides and DNA for applications in bioanalysis or chemical biology2. The 5- or 6-aryluracils can be prepared by heterocyclization or by cross-coupling reactions of halouracils with arylboronic acids or stannanes or metallated uracils with aryl halides. Direct C–H arylation of uracil is an alternative to classical cross-couplings where the preparation of reactive organometallic reagent is avoided. Recently, we have developed regioselective Pd-catalyzed and/or Cu-mediated direct C–H arylations of 1,3-dimethyluracil as a model compound for pyrimidine bases to position C-5 or C-6 3.
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Synthesis and structual assignment of novel 5´-epimeric 3´deoxy-3´,4´-didehydronucleoside-5´-C-phosphonates
Petrová, Magdalena ; Buděšínský, Miloš ; Klepetářová, Blanka ; Rosenberg, Ivan
Epimeric 5´-(RS) dialkyl 3-deoxy-3´,4´-didehydro-5´-C-phophonates were prepared by nucleophilic addition of various dialkyl phosphites to 3´-deoxy-3´,4´-didehydronucleoside-5´-aldehydes. Successful separation,crytstallisation and X-ray analysis of a pair of epimeric 5´-C-phosphonates, followed by correlation with a series of NMR parameters, led to efficacious configuration assignment of individual epimers in the mixtures.
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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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