Synthesis of pyrazole derivatives of 1h -imidazo[4,5-b] pyridines

The pyrazole ring is a prominent structural moiety found in numerous pharmaceutically active compounds. This is mainly due to the easy preparation and the important biological activity. Pyrazole framework plays an essential role in biologically active compounds and therefore represents an interesting template for combinatorial as well as medicinal chemistry. The pyrazole nucleus is a ubiquitous feature of pharmacological interest and has been proven to be a fertile source of medicinal agents such as antibacterial, antifungal, antiviral, antitubercular, antiamoebic, antiandrogenic, etc. Some of these compounds have also exhibited anti-inflammatory , antidiabetic, anaesthetic, analgesic and antiparasitic properties. Many pyrazoles have been found to be luminescent and fluorescent agents. In addition pyrazoles have played a crucial role in the development of theory in heterocyclic chemistry and also used extensively as useful synthon in organic synthesis. It is interesting to note that fused bis-pyrazoles are reported as well known pharmacophores. This has prompted us to synthesize some of the pyrazolopyrazole derivatives by using thiosemicarbazide . It has been considered worthwhile to incorporate a suitable functionality into these derivatives to increase their pharmacological activity. The general synthetic procedures used in the preparation of these compounds involved the cyclisation of Schiff’s bases.