P-stereogenic ligands: synthesis and applications in transition-metal asymmetric homogeneous catalysis

Asymmetric catalysis is nowadays an indispensable tool to prepare enantioenriched compounds both in research laboratories and in industry. One of the most successful approaches is the use of soluble catalytic precursors that are transition metal complexes with the appropriate optically pure ligands. Arguably, phosphine ligands are the most important type of chiral ligands for many processes. At the beginning of asymmetric homogeneous catalysis, more than 60 years ago, the first chiral phosphines employed were P- stereogenic, i.e., bearing a phosphorus atom with three different substituents. Despite the initial outstanding results of these ligands in catalytic hydrogenation, their use was mostly abandoned due to their lengthy synthesis and the development of other phosphines that were easier to prepare and gave equally good results. It is now obvious, however, that even the most successful ligands are not universal and therefore all sources of chirality are intensively investigated, including ligands with stereogenic phosphorus atoms.

The presentation will give a brief account of the history and the main preparative methods of P-stereogenic ligands as well as their performance in asymmetric homogeneous catalysis. After this part, the work previously developed within the speaker’s research group with this kind of ligands will be outlined and some of the results in Pd- and Ru-catalysed reactions will also be described.