Lay summary
We developed an extremely facile, new and generally applicable concept for the high yield synthesis phosphorous amidite based pincer complexes. Moreover, we could demonstrate that these kind of complexes are extremely efficient catalysts in Suzuki reactions. Their applicability in the Heck reaction will be tested. Beside the elucidation of the limits of these catalysts in these catalyses, efforts to widen the scope of the Heck- and Suzuki-reactions to functionalized precursors e.g. are planned. Our research will mainly be focused on the development of new principles for C-C bond forming reactions via C-H activations. Since extremely facile C-H activations were obtained in the synthesis of pincer complexes catalytic C-C coupling reactions via C-H activation seems very promising. Indeed, the most important feature for the efficient C-H bond activation is to bring the unactivated C H bonds of the substrates in the close proximity of the metal center in order to achieve metal insertion. Phosphorous amidite ligand systems may play a very important role regarding this point and possibly could give a novel solution for this problem allowing the general applicability of NH-functionalized precursors in C-H activation processes. It is known that the P-N bonds of phosphorous amidite ligands are relatively labile and can be cleaved by secondary or primary amines. This was proven by the synthesis of pincer complexes via facile P-N and C-H activations. Thus, the selective, efficient and catalytic C-H bond activation under mild conditions of at least NH-containing substrates seems possible. Most important, the activated substrate is reversibly bounded via the P-N bond and after the coupling reaction the release of the product can take place. Hence, this reaction principle may not only allow the vinylation of aniline, benzylamine and its derivatives e.g., but possibly can be widened to various C-C coupling reactions of aromatic, olefinic and aliphatic prim. or sec. amines, since all NH-containing substrates will be “coordinated” in the close proximity of the metal center.