Xanthines fluoride

Potentially tautomeric pyrimidines and purines are /V-alkylated under two-phase conditions, using tetra-n-butylammonium bromide or Aliquat as the catalyst [75-77], Alkylation of, for example, uracil, thiamine, and cytosine yield the 1-mono-and 1,3-dialkylated derivatives [77-81]. Theobromine and other xanthines are alkylated at N1 and/or at N3, but adenine is preferentially alkylated at N9 (70-80%), with smaller amounts of the N3-alkylated derivative (20-25%), under the basic two-phase conditions [76]. These observations should be compared with the preferential alkylation at N3 under neutral conditions. The procedure is of importance in the derivatization of nucleic acids and it has been developed for the /V-alkylation of nucleosides and nucleotides using haloalkanes or trialkyl phosphates in the presence of tetra-n-butylammonium fluoride [80], Under analogous conditions, pyrimidine nucleosides are O-acylated [79]. The catalysed alkylation reactions have been extended to the glycosidation of pyrrolo[2,3-r/]pyrimidines, pyrrolo[3,2-c]pyridines, and pyrazolo[3,4-r/]pyrimidines (e.g. Scheme 5.20) [e.g. 82-88] as a route to potentially biologically active azapurine analogues. 

Menzel et al. [19] Glucose Ethanol Phosphate Saccharomyces cerevisiae, Acremonium chrysogenum and recombinant baby hamster kidney (rBHK) cell cultivations Co-immobilised glucose oxidase and peroxidase Co-immobilised alcohol oxidase and peroxidase Co-immobilised nucleoside phosphorylase, xanthin oxidase and peroxidase Potentiometric, fluoride sensitive (pF), buffer capacity insensitive electrolyte isolator semiconductor capacitor (pF-EIS-CAP) chip ... 

An interesting alkylation reaction for purines, such as adenine or xanthine, by tetrabutylammo-nium fluoride catalyzed alkylation with trialkyl phosphates has been recently described. This reaction also works for the corresponding nucleosides and nucleotides with high yield. In the case of adenine, alkylation gives predominantly the N9 product 22. ... 

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