Quinolines and isoquinolines

This chapter assesses quinolines and isoquinolines. Quinoline and isoquinoline are two isomeric heterocyclic systems, which can be envisaged as being constructed from the fusion of a benzene ring at the C2/C3 and C3/C4 positions of pyridine respectively. They are both ten π-electron aromatic heterocycles. Like pyridine, they are moderately basic. Indeed, quinoline is sometimes used as a high boiling-point basic solvent. As with pyridine, the nitrogen atoms of quinoline and isoquinoline each bear a lone pair of electrons not involved in aromatic bonding which can be protonated, alkylated, or complexed to Lewis acids. The chapter then considers the synthesis, electrophilic substitution, nucleophilic substitution, and anion chemistry of quinoline and isoquinoline.