Use of monodentate ligands in the asymmetric ketone hydrogenation

PhD ceremony: Mr. B. Stegink, 14.45 uur, Academiegebouw, Broerstraat 5, Groningen

Title: Use of monodentate ligands in the asymmetric ketone hydrogenation

Promotor(s): prof. J.G. de Vries, prof. B.L. Feringa, prof. A.J. Minnaart

Faculty: Mathematics and Natural Sciences

Many compounds which occur in nature are chiral. This means the compound can exist in two different forms, enantiomers, which are each others mirror image. Enantiomers are physically almost identical but their biological function can be completely different. For an organic chemist it is very important to be able to get one of these two enantiomers selectively in hand.

One of the methods for getting enantiomerically enriched compounds in hand is via asymmetric hydrogenation. During a hydrogenation a double bond within the molecule reacts, with the help of a catalyst, with a molecule of hydrogen gas, resulting in a single bond.

During my promotion research I focused on trying to find new catalysts for the asymmetric hydrogenation of different types of ketones. The focus in this research was set on the use of, so called, monodentate ligands especially phosphoramidites. Monodentate ligands, and especially phosphoramidites, are much easier to synthesize compared to the normally used bidentate ligands. This easy synthesis makes them very suitable for fast screening increasing the change of finding a good performing catalyst drastically.

I was able to develop several ruthenium based catalysts baring one or two phosphoramidite ligands which are able to hydrogenate several types of ketones in high yield and excellent selectivities.

These methods could, in the future, be used in the synthesis of biologically active compounds for, for instance, the pharmaceutical industry.