A simple and efficient one-pot novel synthesis of pyrazolo[3,4-b][1,8]naphthyridine and pyrazolo[3,4-d]pyrimido[1,2-a]pyrimidine derivatives as anti-inflammatory agents

An efficient one-pot synthesis of novel pyrazolo[3,4-b][1,8]naphthyridine and pyrazolo[3,4-d]pyrimido[1,2-a]pyrimidine derivatives has been investigated from the reaction of 2-amino (pyrimidine or pyridine), aromatic aldehydes and 3-methyl-1-phenyl-2-pyrazolin-5-one. All synthesized compounds were evaluated for in vivo anti-inflammatory activity using carrageenan-induced rat paw edema assay. Compounds 4a, 4e, 4g, 5a, 5b (80%) and 5c (86%) showed good to excellent results when compared with the anti-inflammatory active standard drug diclofenac Na (93%). On the basis of the structure–activity relationship, the anti-inflammatory activity of pyrazolo[3,4-d]pyrimido[1,2-a]pyrimidine derivatives has been found to be much better than pyrazolo[3,4-b][1,8]naphthyridine derivatives.