Aromatic heterocycle formation

Knorr pyrrole synthesis

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This synthesis is so important, it was given the name of its inventor: Ludwig Knorr.

In this reaction, the amino group froms an imine with one of the diketone carbonyl groups. The enamine intermediate then cyclizes onto the other ketone carbonyl and water is removed to form the aromatic heterocycle.

A. R. Katritzky, D. L. Ostercamp and T. I. Yousaf, Tetrahedron, 1987, 43, 5171–5186.