Chemistry and Biological Activities of 6-pyridin-3-yl-1H-pyrazolo[3,4-b]pyridin-3-amines (I)

4-(Phenyl or p-methoxyphenyl)-6-thioxo-1,6-dihydro-2,3'-bipyridine-5-carbonitriles 1a,b reacted with either iodomethane followed by hydrazine hydrate or hydrazine hydrate directly to give the corresponding 6-pyridin-3-yl-1H-pyrazolo[3,4-b]pyridin-3-amines 4a,b. Compounds 4a,b were used as the starting materials of the present study, they reacted with nitrous acid to give the corresponding diazonium salts 5a,b. The latter compounds reacted further via their coupling with several active -CH2- containing reagents 6, 9a,b, 11a,b, 14, 17 and 19 aiming to synthesize several derivatives of pyrido[2',3':3,4]pyrazolo[5,1-c][1,2,4]triazines 8a,b, 10a-d, 12a,b, 15a,b, 18a,b, and 20b. The structures of all newly synthesized heterocyclic compounds were elucidated by considering the data of elemental analyses, IR, H-1 NMR and mass spectrometry. All newly synthesized heterocyclic compounds were tested as anti-Alzheimer and anti-cox2 reagents and exhibit promising results.