Preparation of substituted pyrroles via Ru(II)-catalyzed coupling of alkynes with enamides

An efficient ruthenium-catalyzed oxidative cyclization of enamides with alkynes in water or dimethoxyethane leading to the pyrrole derivatives is reported. Typically, a mixture of ethyl 2-(acetylamino)acrylate, diphenylacetylene, [Ru(p-cymene)Cl2] (2 mol %), KPF6, and Cu(OAc)2 in water was heated under refluxing conditions providing the N-acetylated pyrrole product in 95% yield.