Ru(II)-catalyzed and Cu(II)-mediated Carbene Migratory Insertion in the Synthesis of Trisubstituted Pyrroles from Isoxazoles.

A convenient, “one-pot” synthesis of trisubstituted pyrroles via a Ru(II)-catalyzed and Cu(II)-mediated reaction of substituted isoxazoles with sulfonylhydrazones has been developed. A series of highly functionalized pyrroles are obtained via a synergistic formation of new C-C, C-N bonds. Mechanistic investigations were carried out to propose the plausible pathway. This protocol provides a facile and an expeditious approach to the synthesis of various heterocyclic compounds bearing the pyrrole skeleton.