Density Functional Theory-Inspired Design of Ir/P,S-Catalysts for Asymmetric Hydrogenation of Olefins

In silico-based optimization of Ir/P,S-catalysts for the asymmetric hydrogenation of unfunctionalized olefins using (E)-1-(but-2-en-2-yl)-4-methoxybenzene as a benchmark olefin has been carried out. DFT calculations revealed that the thioether group has a major role in directing the olefin coordination. This, together with the configuration of the biphenyl phosphite group, has an impact in maximizing the energy gap between the most stable transition states leading to opposite enantiomers. As a result, the optimized catalyst proved to be efficient in the hydrogenation of a range of alkenes with the same substitution pattern and olefin geometry as the benchmark olefin, regardless of the presence of functional groups with different coordination abilities (ee values up to 97%). Appealingly, further modifications at the thioether groups and at the biaryl phosphite moiety allowed the highly enantioselective hydrogenation of olefins with different substitution patterns (e.g., α,β-unsaturated lactones and lactams, 1,1′-disubstituted enol phosphinates, and cyclic β-enamides; ee values up to >99%).We gratefully acknowledge financial support from the Spanish Ministry of Science and Innovation (PID2019-104904GB-I00, PGC2018-100780-B-I00, and PGC2018-096616-B-I00), European Regional Development Fund (AEI/FEDER, UE), the Catalan Government (2017SGR1472), and the University of Alicante (VOGROB-316FI). M.B. also thanks the URV for generous support

Extending the substrate scope in the hydrogenation of unfunctionalized tetrasubstituted olefins with Ir-P stereogenic aminophosphine-oxazoline 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 not only able to efficiently hydrogenate a range of indene derivatives (ee's up to 96%) but also 1,2-dihydro-napthalene derivatives and acyclic olefins (ee's up to 99%), which both constitute the most challenging substrates for this transformation

P-Stereogenic Ir-MaxPHOX: A Step toward Privileged Catalysts for Asymmetric Hydrogenation of Nonchelating Olefins

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

Asymmetric Pd-catalyzed allylic substitution using a large sugar-based monophosphite ligand library. Scope and limitations.

Asymmetric Pd-catalyzed allylic substitution using a large sugar-based monophosphite ligand library. Scope and limitations.Article en open accesWe have applied a modular sugar-based phosphite ligand library for the Pd-catalyzed allylic substitution reactions of several substrates. These ligands are derived from D-(+)-glucose, D-(+)-galactose and D-(+)-fructose, which lead to a wide range of sugar backbones, and contain several substituents at the C-3 carbon of the furanoside backbone and several substituents/configurations in the biaryl moiety, with different steric and electronic properties. Systematic variation of the ligand parameters indicates that the catalytic performance (activities and enantioselectivities) is highly affected by sugar backbone, the substituents at the C-3 carbon of the furanoside backbone, the configurations at the C-3 and C-4 carbons of the ligand backbone and the type of substituents/configurations in the biaryl phosphite moiety as well as the substrate type. For disubstituted substrates moderate enantioselectivities (up to 72%) were achieved using ligand L8d, while for monosubstituted substrates the highest enantioselectivities (up to 40%) were obtained using ligand L9a