A synthesis of fuctionalized 2-amino-3-cyano pyrroles from terminal alkynes, sulfonyl azides and phenacylmalononitriles

A new strategy for the construction of functionalized 2-amino-3-cyano pyrroles has been developed. The reactions involved a copper-catalyzed azide-alkyne cycloaddtion reaction between terminal alkynes and sulfonyl azides followed by generation of N-sulfonoketenimine intermediates. Interception of these reactive ketenimines by phenacylmalononitriles in the presence of copper(I) iodide and Et3N afforded the expected products. The reaction proceeded smoothly in THF at ambient temperature to afford the target compounds in 70-92% yields and excellent regioselectivity. Evidence for the structure of a typical product is obtained from single-crystal X-ray analyses.