Knorr pyrrole synthesis

The Knorr pyrrole synthesis is a widely used chemical reaction that synthesizes substituted pyrroles (3). The method involves the reaction of an α-amino-ketone (1) and a compound containing a methylene group α- to (bonded to the next carbon to) a carbonyl group (2).



Method
The mechanism requires zinc and acetic acid as catalysts. It will proceed at room temperature. Because α-amino-ketones self-condense very easily, they must be prepared in situ. The usual way of doing this is from the relevant oxime.