Coupling Reactions

Coupling reactions, most prominently Heck and Suzuki couplings but also Sonogashira coupling and allylic substitution, are established catalytic transformations for the synthesis of fine chemicals. The recovery of catalytically active complexes from such coupling reactions, by the concept of covalent binding to soluble polymers, has been studied by various research groups. This research, addressed in the following section, has been carried out for the largest part only since the late 1990s. On a different level, since approximately the same time, coupling reactions with palladium colloids as catalysts have also attracted substantial interest. In addition to the synthetic utility and also catalyst re-use, the challenging question of the mechanistic function of colloids has been the focus of attention. The colloids employed are usually stabilized either by polymers or by low molecular weight surfactants. Coupling reactions with colloids are discussed in Sections 7.4.2.2 and 7.4.2.3.