6-Membered heteroaromatic rings are common in drug molecules. The structure of the ring can have a significant effect on the ADME properties of a compound. Pyridine is the most common in drugs but pyrimidine is also well represented. The other 6-membered rings are less common but are still seen. This course covers pyridine, pyrimidine, pyridazine, pyrazine and triazines. It describes some of the methods used to build the rings and touches on their reactivity towards electrophilic substitution, lithiation, nucleophilic aromatic substitution and palladium catalysed cross-coupling.