Nomenclature. Electron-rich heteroaromatic rings reactivity pyrrole, furan, thiophene and indol. Paal-Knorr, Knorr and Hantzsch synthesis of pyrrolic ring; Paal-Knorr and Feist-Benary synthesis of furanic ring; Paal synthesis of thiophenic ring; Fischer and Reissert synthesis of indolic ring. Electron-poor heteroaromatic rings reactivity pyridine, quinoline and isoquinoline. Use of N-oxides derivatives in of electrophylic aromatic substitution reactions . Chichibabin's reaction. Alkyl derivatives reactivity of pyridine and derivatives. Synthesis from 1,5-diketones, followed by oxidation, and Hantzsch's synthesis of pyridinic ring. Skraup synthesis of quinoline and Biskler-Napieralsky synthesis of isoquinoline. Diazines reactivity. Pinner synthesis of pyrimidine. Synthesis of barbituric acid.