Paal-Knorr Pyrrole Synthesis

The Paal-Knorr Pyrrole Synthesis is the condensation of a 1,4-dicarbonyl compound with an excess of a primary amine or ammonia to give a pyrrole.

The reaction can be conducted under neutral or weakly acidic conditions. Addition of a weak acid such as acetic acid accelerates the reaction, but the use of amine/ammonium hydrochloride salts or reactions at pH < 3 lead to furans as main products (Paal-Knorr Furan Synthesis).

Paal-Knorr Furan Synthesis