Aim and Objective: 1-Аlkyl-3,7-dihydro-1H-purine-2,6-diones containing no substituents in the N7 position
can be synthesized only using protecting groups, for example, benzyl protection. However, in the case of
synthesis of 1-benzyl-3,7-dihydro-1H-purine-2,6-diones, the use of benzyl protection may lead to simultaneous
debenzylation of both N1 and N7 positions. Therefore, it is necessary to use other protective groups for the synthesis
Materials and Methods: 8-Bromo- and 8-amino-substituted 1-benzyl-3-methyl-3,7-dihydro-1H-purine-2,6-diones
unsubstituted in the N7 position were synthesized with the use of thietanyl protecting group. The thietane ring was
introduced via the reaction of 8-bromo-3-methyl-3,7-dihydro-1H-purine-2,6-dione with 2-chloromethylthiirane,
giving rise to 8-bromo-3-methyl-7-(thietan-3-yl)-3,7-dihydro-1H-purine-2,6-dione. The subsequent alkylation
with benzyl chloride yielded 1-benzyl-8-bromo-3-methyl-7-(thietan-3-yl)-3,7-dihydro-1H-purine-2,6-dione,
which was oxidized with hydrogen peroxide to be converted to 1-benzyl-8-bromo-3-methyl-7-(1,1-dioxothietan-
3-yl)-3,7-dihydro-1H-purine-2,6-dione. This product reacted with amines to give 8-amino-substituted 1-benzyl-3-
methyl-7-(1,1-dioxothietan-3-yl)-3,7-dihydro-1H-purine-2,6-diones. The reaction of 8-substituted 1-benzyl-3-
methyl-7-(1,1-dioxothietan-3-yl)-3,7-dihydro-1H-purine-2,6-diones with sodium isopropoxide resulted in the removal
of the thietanyl protection and afforded target 8-substituted 1-benzyl-3-methyl-3,7-dihydro-1H-purine-2,6-
diones. The structures of the targets compounds have been deduced upon their elemental analysis and spectral data
(IR, 1H NMR, 13C NMR and 15N NMR).
Results and Discussion: A new 8-substituted 1-benzyl-3-methyl-3,7-dihydro-1H-purine-2,6-diones unsubstituted
in the N7 position were synthesized using thietanyl protecting group.
Conclusion: The present study described a new route to synthesize some new 1,8-disubstituted 3-methyl-3,7-
dihydro-1H-purine-2,6-diones unsubstituted in the N7 position starting from available 8-bromo-3-methyl-3,7-
dihydro-1H-purine-2,6-dione with use of thietanyl protecting group. The advantages of this protocol are the possibility
of the synthesis of 1-benzyl-substituted 3,7-dihydro-1H-purine-2,6-diones, the stability of the thietanyl
protecting group upon nucleophilic substitution by amines of the bromine atom in the position 8, as well as mild
conditions, and simple execution of experiments.