Over the past few years, many pyrazole fused-ring systems, especially with applications in medicinal chemistry, have been published. These include general structures such as pyrazoline, pyrazoline, pyrazoquinoline, pyrazoloisoquinoline, pyrazoline, pyrazolopyrazine, pyrazolopyrazine, pyranopyrazole, pyrano Pyrazoles, pyrazolotriazines and pyrazole fused phosphorus rings.
Tetrahydrofuran is a heterocyclic organic compound with the molecular formula C4H8O. Tetrahydrofuran belongs to ethers and is the complete hydrogenation product of furan. It is a colorless, water-miscible organic liquid with small viscosity at normal temperature and pressure. Because of its long liquid range, it is a commonly used medium polar aprotic solvent. Its main use is as a precursor of high molecular polymers.