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.
Naphthyridine is a class of aromatic heterocyclic compounds whose chemical formula is C8H6N2. They consist of naphthalene bicyclic rings in which two carbon atoms are replaced by nitrogen atoms. There are ten isomers of naphthyridine, because naphthyridine has two benzene rings, has strong π-π conjugation, and has better luminescence properties. Common naphthyridines are 1,8-naphthyridines. There are many kinds of 1,8-naphthyridine derivatives, and they are widely used.