Enone-Alkyne Reductive Coupling: A Versatile Entry to Substituted Pyrroles

The reductive coupling of enones or enals with alkynes, followed by olefin oxidative cleavage and Paal-Knorr cyclization, provides a versatile entry to a variety of pyrrole frameworks. A number of limitations of alternate entries to the requisite 1,4-dicarbonyl intermediate are avoided. Classes of pyrroles that are accessible by this approach include 2,3-, 2,4-, 1,2,3-, 1,2,4-, 2,3,5-, and 1,2,3,5-substituted monocyclic pyrroles as well as a number of fused-ring polycyclic derivatives.