Cinnoline

Cinnoline is a heterocyclic aromatic organic compound with the chemical formula C₈H₆N₂. It consists of a benzene ring fused to a pyrimidine ring. Cinnoline is an isomer of quinazoline, phthalazine, and quinoxaline, all of which share the same molecular formula but differ in the arrangement of the two nitrogen atoms within the bicyclic ring system.

Cinnolines and their derivatives are of interest in medicinal chemistry and materials science due to their diverse pharmacological activities and unique electronic properties. They have been investigated for potential use as anticancer, anti-inflammatory, and antimicrobial agents. Furthermore, cinnoline derivatives find applications as ligands in coordination chemistry and as building blocks for the synthesis of more complex organic molecules.

The synthesis of cinnolines typically involves various cyclization reactions, such as the Richter cinnoline synthesis and other modifications of the diazonium salt approach. The reactivity of the cinnoline ring system is influenced by the presence of the two nitrogen atoms, which can affect the electron density and reactivity towards electrophilic and nucleophilic attack.