Synthesis of novel pyrazolyl tetrazoles as selective COX-2 inhibitors

A series of novel pyrazolyl tetrazoles were synthesized by introducing tetrazole moiety at the fourth position of 1,3-substituted pyrazole nucleus. Synthesis was carried out by cyclization of different pyrazolonitriles using sodium azide in the presence of triethylammonium chloride as phase transfer catalyst. The structures of the synthesized compounds were confirmed on the basis of physical and spectral data. Among the synthesized compounds, 4b and 4e displayed significant anti-inflammatory activity with no observable ulcerogenic effect when compared with diclofenac sodium. Furthermore, compounds 4b and 4e were found to have COX-2 selectivity with a ratio of 0.44 and 0.48, respectively.