Transition metal-catalyzed cascade reactions are an elegant approach to complex molecular scaffolds. Besides their esthetics and increase in structural complexity, they have also become mechanistic challenges for the combination of organometallic elementary steps. As a consequence, cascade reactions have revolutionized synthetic strategies and conceptual thinking. The authors highlight cyclization via carbopalladation and acylpalladation and Heck-pericyclic sequences. They discuss p-allyl palladium-based cascade reactions, Michael-type additions as an entry to transition-metal-promoted cyclizative transformations, and sequential or consecutive palladium-catalyzed processes, and show Pauson-Khand cascades, metal-catalyzed cyclizations of acyclic precursors, as well as cascade and sequential ruthenium-catalyzed transformations. Therefore, the reader finds overview of an exciting and highly dynamic field of a new and innovative methodological concept.
