Guanine methylated compounds

The effect of the N7 methylation in guanine on the one-bond CC and CN couplings has been studied by Ruszczyhska et al The DFT calculated data for the parent guanine and the experimental J values measured for the corresponding nucleoside triphosphate have been compared with those for the N7 methylated compounds, which allowed the authors to estimate the charge distribution in the latter. 

PES has been applied to study biologically active molecules with amino groups and their constituents like nucleic bases and related compounds (e.g. adenine, guanine, thymine, cytosine, hypoxanthine and their methyl derivatives)113-120 and amino acids92,121,122 or their methyl esters123. 

The bases that occur in nucleic acids are aromatic heterocyclic compounds derived from either pyrimidine or purine. Five of these bases are the main components of nucleic acids in all living creatures. The purine bases adenine (abbreviation Ade, not A ) and guanine (Gua) and the pyrimidine base cytosine (Cyt) are present in both RNA and DNA. In contrast, uracil (Ura) is only found in RNA. In DNA, uracil is replaced by thymine (Thy), the 5-methyl derivative of uracil. 5-methylcyto-sine also occurs in small amounts in the DNA of the higher animals. A large number of other modified bases occur in tRNA (see p. 82) and in other types of RNA. 

Acyclonucleosides, such as 9-[(2-hydroxyethoxy)methyl]guanine (acyclovir, 1) or -adenine, are prepared by alkylation of 2,6-dichloropurine or 6-chloropurine with l-(benzyloxy)-2-(chloromethoxy)ethane to give predominantly the N9 products in moderate yield. Amina-tion and debenzylation give the target compounds. 

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