Cascade Palladium- and Copper-Catalysed Aromatic Heterocycle Synthesis: The Emergence of General Precursors

Several privileged starting materials that allow access to a variety of different heterocyclic scaffolds through judicious choice of reaction conditions (and coupling partner) have emerged. This microreview focuses on the development and use of four of these starting material types in cascade reactions involving the palladium- or copper-catalysed formation of aromatic carbon-nitrogen, carbon-oxygen or carbon-sulfur bonds.