Chapter 6 - Multicomponent Reaction Sequences Using Palladacyclic Complexes

Abstract

Multicomponent reactions, defined as synthetic protocols that join together three or more substrates in a highly regio- and stereoselective manner to deliver structurally complex organic molecules, have seen a dramatic rise in applications in all fields of organic synthesis. Palladium catalysis encompassing number of historically significant Nobel prize-winning transformations have played a prominent role in the development of novel multicomponent reactions. An important subset of the palladium-catalyzed multicomponent reactions feature a cyclopalladated complex as the key component or reactive intermediate. In this review, we highlight most notable multicomponent reactions, including polymerizations, reported over the past decade (past 2008) that feature palladacycles in all different mechanistic roles, including: (i) multicomponent reactions using palladium catalyst with a cyclopalladated auxiliary ligand; (ii) multicomponent reactions involving in situ palladation of the substrate; (iii) multicomponent reactions with a stoichiometric cyclopalladated complex. Selected mechanistic studies that are relevant to elucidating the role played by cyclopalladated complexes in carbon-carbon bond formation are discussed where appropriate.