A series of novel 6-functionalized-5-amino-3-methyl-1-phenyl-1H-furo
[3,2-e]pyrazolo[3,4-b]pyrazines (4a–c) was synthesized by the reaction
of 3-methyl-6-oxo-1-phenyl-6,7-dihydro-1H-pyrazolo[3,4-b]pyrazine-5-
carbonitrile (2) with α-halocarbonyl compounds such as: diethyl
2-bromomalonate, phenacyl bromide and chloroacetone. Cyclocondensation
of the amino benzoyl 4b with diethyl malonate yielded the
oxopyridine carboxylate derivative 5. Also, the starting intermediate
amino ester compound 4a was allowed to react with ethanol amine
to afford the hydroxyethyl caboxamide derivative 6. Furthermore,
hydrazinolysis of the amino ester 4a afforded the corresponding
amino carbohydrazide 7 which was used as a versatile precursor for
synthesis of other heterocyclic compounds attached or fused to the
furopyrazolopyrazine moiety. The chemical structures of the newly
synthesized compounds were confirmed on the basis of elemental
and spectral analyses containing FT-IR, 1H NMR, 13C NMR, and mass
spectrometry hoping these molecules should allow us to investigate
their pharmacological activities in the future study.