Palladium Pincer Complex Catalyzed Funtionalization of Electrophiles

Lukasz      T. Pilarski; Kalman      J. Szabo

doi:10.2174/138527211797247987

Abstract

This review describes the usefulness of palladium pincer complexes in catalytic transformations of various electrophiles. We discuss two basic approaches to the functionalization of electrophiles: (i) palladium pincer complex catalyzed additions of allylic and other substrates to electrophiles, such as sulfonyl imines, aldehydes and related reagents; and (ii) pincer complex catalyzed generation of allylmetal reagents (such as boronates and other species) followed by a direct or palladium-catalyzed functionalization of the electrophiles under one-pot conditions. The study is focused on the reactivity and selectivity aspects of pincer complex catalysis. We show, for example, that allylations of imines and aldehydes are easier to perform with pincer complexes bearing π-acceptor phosphine ligands, while generation of organometallic species can be efficiently achieved by σ-donor, selenium or nitrogen containing pincer ligands. We present several examples of chiral pincer complexes in asymmetric catalysis. The high stability and well-defined stoichiometry of pincercomplexes allow a rational design of asymmetric catalytic reactions for carbon-carbon and carbon-heteroatom bond formations. Briefly, we have also reviewed the new emerging field of pincer complexes in Pd(II)/Pd(IV)-based catalytic cycles. These processes allow redox reactions involving pincer complex catalysts without altering of the typical pincer complex topology.

Keywords: Palladium, catalysis, electrophiles, organoboronates, allylation, asymmetric catalysis, chiral metal complexes, pincer complexes, cyclopropanations, Michael additions, enantioselective transformations, Palladium Pincer Complexes, Allylic Stannanes, Allylic Cyanides, Benzylic Cyanides