Palladium-Catalyzed Cascade Cyclization/Alkynylation Reactions.

Palladium-catalyzed cascade cyclization reactions have witnessed significant improvements in recent years. Among them, palladium-catalyzed cascade cyclization/alkynylation are especially attractive, which can assemble structurally diverse monocyclic, bicyclic, fused polycyclic, and spirocyclic skeletons with excellent chemoselectivities. In this Minireview, palladium-catalyzed cascade cyclization/alkynylation have been summarized and discussed in detail with focus on oxypalladation and aminopalladation-initiated cascade cyclization, intramolecular Heck-type cascade cyclization, carbocyclizations, cascade cyclizations, and other types of cascade cyclization reactions. Some significant and representative synthetic methodologies and their synthetic applications and reaction mechanisms have also been described.