Synthesis of Substituted Pyrroles from Skipped Diynes

Significance

Described here is the synthesis of substituted pyrrole 2-carboxylate esters by a metal-free reaction of skipped diynes with primary amines. The key to this domino process are the Michael acceptor properties of the alkynoate. The final pyrrole products result from a [3,3]-sigmatropic rearrangement. No evidence for any of the intermediates is provided. The reaction can be performed under conventional or microwave heating, the first being a slightly more efficient reaction but the latter being faster (30 min).