The work presented in this thesis is focused on asymmetric synthesis and mechanistic insights of hydrogenations catalyzed by Ir-N,P- and Rh-diphosphine complexes. The developed methodologies provide an efficient catalytic system to access optically enriched compounds by exploiting the effect of the N,P ligand structure and investigating the enantioconvergent behavior.

The first part of the work presented (Chapter 2) is focused on the stereoselective synthesis of chiral fluorinated compounds with one or two contiguous stereogenic centers. New N,P ligands were prepared and investigated. In the first project, 1,2-fluorohydrins were synthesized in high enantioselectivity. In the second project, fluoroalkenes with and without an adjacent carbonyl group were both hydrogenated successfully. In the third project, organofluorine compounds having two contiguous stereogenic centers were prepared in excellent diastereoselectivity and enantioselectivity. Notably, the frequently observed side reaction of defluorination was addressed, and only minor or negligible defluorination was observed.

In the second part (Chapter 3), a wide range of variously substituted isomeric enamide mixtures were hydrogenated in excellent ees. Both E and Z isomers gave the same enantiomer with similar level of enantioselectivities. Experimental and Density functional theory (DFT) studies revealed that different mechanistic pathways are operative for the different classes of substrates. DFT studies gave a better understanding of the enantioconvergent hydrogenation.

Chapter 4 focuses on the enantioconvergent isomerization-hydrogenation of allylic alcohols. A variety of allylic alcohols, each consisting of a mixture of four isomers, were converted to the corresponding tertiary alcohols with up to 99% ee and 99:1 d.r. DFT calculations and control experiments revealed that the 1,3-rearrangement is the crucial stereodetermining element of the reaction. A rationale that explains the origin of selectivity for this enantioconvergent hydrogenation was also proposed.

The final part (Chapter 5) is focused on the asymmetric reduction of arenes using the classical Rh-diphosphine catalyst. A duality of the commonly used Rh precursor was discovered and resulted in an asymmetric hydrogenation of arenes via cascade hydrogenation or direct hydrogenation. The generality was evaluated and showed high compatibility between Rh-diphosphine catalytic system and a number of different substrates.