The Ir-MaxPHOX-type catalysts demonstrated high catalytic performance in the hydrogenation of a wide range of nonchelating olefins with different geometries, substitution patterns, and degrees of functionalization. These air-stable and readily available catalysts have been successfully applied in the asymmetric hydrogenation of di-, tri-, and tetrasubstituted olefins (ee′s up to 99%). The combination of theoretical calculations and deuterium labeling experiments led to the uncovering of the factors responsible for the enantioselectivity observed in the reaction, allowing the rationalization of the most suitable substrates for these Ir-catalysts.

Air-stable and readily available Ir-catalyst precursors modified with MaxPHOX-type ligands have been successfully applied in the challenging asymmetric hydrogenation of tetrasubstituted olefins under mild reaction conditions. Gratifyingly, these catalyst precursors are able to efficiently hydrogenate not only a range of indene derivatives (ee's up to 96%) but also 1,2-dihydronapthalene derivatives and acyclic olefins (ee's up to 99%), which both constitute the most challenging substrates for this transformation. Letter pubs.acs.org/OrgLett

A family of phosphite/phosphinite‐thioether ligands have been tested in the Ir‐catalyzed asymmetric hydrogenation of a range of olefins (50 substrates in total). The presented ligands are synthesized in three steps from cheap indene and they are air‐stable solids. Their modular architecture has been crucial to maximize the catalytic performance for each type of substrate. Improving most Ir‐catalysts reported so far, this ligand family presents a broader substrate scope, covering different substitution patterns with different functional groups, ranging from unfunctionalized olefins, through olefins with poorly coordinative groups, to olefins with coordinative functional groups. α,β‐Unsaturated acyclic and cyclic esters, ketones and amides were hydrogenated in enantioselectivities ranging from 83 to 99% ee. Enantioselectivities ranging from 91 to 98% ee were also achieved for challenging substrates such as unfunctionalized 1,1′‐disubstituted olefins, functionalized tri‐ and 1,1′‐disubstituted vinyl phosphonates, and β‐cyclic enamides. The catalytic performance of the Ir‐ligand assemblies was maintained when the environmentally benign 1,2‐propylene carbonate was used as solvent.

We have identified a successful family of simple P-stereogenic N-phosphine–phosphite ligands for the Rh-catalyzed asymmetric hydrogenation of olefins. These catalysts show excellent enantiocontrol for α-dehydroamino acid derivatives and α-enamides (ee’s up to >99%) and promising results for the more challenging β-analogues (ee’s up to 80%). The usefulness of these catalytic systems was further demonstrated with the synthesis of several valuable precursors for pharmacologically active compounds, with ee’s at least as high as the best ones reported previously (up to >99%).

We studied for the first time the potential of novel and simple Ir/thioether-NHC complexes in the asymmetric hydrogenation of unfunctionalized olefins and cyclic β-enamides. For comparison, we prepared and applied the analogues thioether–phosphinite/phosphite complexes. We found that the efficiency of the new Ir/thioether-NHC catalyst precursors varies with the type of olefin. Thus, while the Ir/thioether-NHC catalyst precursors provided lower catalytic performance than their related Ir/thioether-P complexes in the hydrogenation of olefins lacking a coordinating group, the catalysts had similar good performance for the reduction of functionalized olefins (e.g., tri- and disubstituted enol phosphonate derivatives). Catalytic results together with the studies of the reactivity toward H2 indicated that the thioether-carbene design favors the formation of inactive trinuclear species, which are responsible for the low activities obtained with these carbene-type catalysts. Nevertheless, this catalyst deactivation can be avoided by using functionalized olefins such as enol phosphonates. We also report the discovery of simple-to-synthesize Ir/thioether-P catalysts containing a simple backbone that gave high enantioselectivities for some trisubstituted olefins, some challenging 1,1′-disubstituted olefins, and cyclic β-enamides.