Pyrazolo[5,1-c][1,2,4]triazole: A Promising Emerging Biologically Active Scaffold in Medicinal Chemistry

Nitrogen-containing heterocycles are essential compounds in nature, and their structural and functional diversity inspired the synthesis of a wide range of derivatives with diverse applications as pharmaceuticals, agrochemicals, dyes, polymers, cosmetics, etc. Among them, N-fused heterocycles represent an important category, due to their high potential as biologically active agents. Pyrazolo[5,1-c][1,2,4]triazoles, a class of nitrogen heterobicycles, have multiple applications as dyes and pigments. Also, a number of compounds containing this structure have been investigated for their biological activities. All the main experimental results published in the literature (both articles and patents) regarding the latter are summarized in this review.