3-Aminopyrazolo[4,3-c]pyridine-4,6-dione as a precursor for novel pyrazolo[4,5,1-ij][1,6]naphthyridines and pyrido[4’,3’:3,4]pyrazolo[1,5-a]pyrimidines

ABSTRACT

The versatile, 3-aminopyrazolo[4,3-c]pyridine-4,6-dione (2) was synthesized and allowed to react with aldehydes, aryldiazonium chlorides, chalcones and enaminones to afford regioselectively the novel pyrazolo[4,3-c]pyridine derivatives 4a-c, pyrazolo[4,5,1-ij][1,6] naphthyridines 9a-d and pyrido[4’,3':3,4]pyrazlo[1,5-a]pyrimidines 19a-i. The structure of all the newly synthesized compounds was assigned from elemental analysis and spectral data. Also, the mechanistic aspects for the formation of the newly synthesized compounds is discussed.

GRAPHICAL ABSTRACT

KEYWORDS:

• Pyrazolo[4,5,1-ij][1,6]naphthyridines
• pyrazolo[4,3-c]pyridines
• pyrido[4′,3′:3,4]-pyrazlo[1,5-a]pyrimidines