Efficient synthesis of some novel furo[3,2-e]pyrazolo[3,4-b]pyrazines and related heterocycles

ABSTRACT

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.

GRAPHICAL ABSTRACT

KEYWORDS:

• Furopyrazolopyrazine
• pyrazolopyrazine
• pyridofuropyrazolopyrazine
• spectral analyses
• synthesis

Acknowledgments

The authors are very grateful to Professor Dr. Kamal I. Aly, Chairman of Chemistry Department for all the facilities providing to us, and very grateful too to the staff members of Chemistry Department, Faculty of Science, Assiut University for their support during this work.