Chiral Phosphine-phosphoramidite Ligands Research Articles

Ir-catalyzed asymmetric hydrogenation of 2-Aryl-3H-indoles with chiral phosphine-phosphoramidite ligands

An asymmetric synthesis of indolines has been described by using an Ir-catalyzed asymmetric hydrogenation of 2-aryl-3H-indoles with unsymmetrical hybrid chiral phosphine-phosphoramidite ligands. The result indicated that the catalytic performance could be significantly improved by the H8-binaphthyl moiety on this ligand motif. This method is characterized by a high asymmetric induction and a reasonable functional group tolerance, thus providing a concise and efficient approach toward chiral indoline and their derivatives with up to 94 % ee.

Bicyclic Bridgehead Phosphoramidite-Based Hybrid Diphosphorus Ligands: Design, Synthesis, and Application in Catalytic Asymmetric Hydrogenation.

A strategy for chiral ligand design has been developed that allows for incorporation of an achiral bicyclic bridgehead phosphoramidite to generate a class of hybrid diphosphorus ligands for high activity and asymmetric control. Using this concept, a series of chiral phosphine-phosphoramidite ligands bearing the sole chirality at the ligand backbone have been prepared and successfully employed in the Rh-catalyzed asymmetric hydrogenation of 2-vinylanilides for the synthesis of optically active anilines bearing an ortho-tertiary benzylic stereocenter.

Highly Diastereo- and Enantioselective Ir-Catalyzed Hydrogenation of 2,3-Disubstituted Quinolines with Structurally Fine-Tuned Phosphine-Phosphoramidite Ligands.

A highly diastereo- and enantioselective Ir-catalyzed hydrogenation of unfunctionalized 2,3-disubstituted quinolines, especially 3-alkyl-2-arylquinolines, has been realized. The success of this hydrogenation is ascribed to the use of a structurally fine-tuned chiral phosphine-phosphoramidite ligand with a (Sa)-3,3'-dimethyl H8-naphthyl moiety and (Rc)-1-phenylethylamine backbone. The hydrogenation displayed broad functional group tolerance, thus furnishing a wide range of optically active 2,3-disubstituted tetrahydroquinolines in up to 96% ee and with perfect cis-diastereoselectivity.

Rh-Catalyzed Asymmetric Hydrogenation of (Z)-β-Phosphorylated Enamides: Highly Enantioselective Access to β-Aminophosphines.

A catalytic asymmetric hydrogenation of β-phosphorylated enamides for enantioselective access to optically active β-aminophosphine derivatives is reported. Critical to the success of this method was the employment of rhodium catalysis in concert with an unsymmetrical hybrid chiral phosphine-phosphoramidite ligand. A wide range of aromatic β-phosphorylated enamides could be hydrogenated in full conversion and with perfect enantioselectivity even at low catalyst loadings (S/C = 1000). β-Aminophosphine oxides could be readily hydrolyzed and reduced, thus providing an efficient route to catalytically important chiral β-aminophosphines.

ChemInform Abstract: Chiral Phosphine‐Phosphoramidite Ligands in Asymmetric Catalysis

AbstractReview: 53 refs.

ChemInform Abstract: Asymmetric Hydrogenation of α‐Keto Phosphonates with Chiral Phosphine—Phosphoramidite Ligands.

Abstract Rh-catalyzed asymmetric hydrogenation of challenging α-keto phosphonates has been developed. With a new chiral phosphine–phosphoramidite ligand, a wide range of α-keto phosphonates were hydrogenated to afford the corresponding ( R )-α-hydroxy phosphonates with moderate to good enantioselectivities (up to 87% ee).

Synthesis of new N-substituted chiral phosphine–phosphoramidite ligands and their application in asymmetric hydrogenations and allylic alkylations

Phosphine–phosphoramidite ligands containing a 2,4-pentanediyl backbone, BINOL moieties, and Me, Bn or Ph substituent on the nitrogen were synthesized and fully characterized. The electronic effect of the N-substituents was examined by 31P NMR of their corresponding seleno-phosphate-amide and phosphine–selenide derivatives. The new ligands together with their earlier reported derivatives were tested in the palladium catalyzed asymmetric allylic alkylation of rac-(E)-1,3-diphenylallyl acetate. Remarkably high activity (up to 1780h−1 turnover frequency) and first order kinetics were observed by facilitating nucleophile formation. The substituent at the nitrogen and the configuration of chiral moieties had a high impact on the enantioselectivity. The new ligands were also tested in the rhodium-catalyzed asymmetric hydrogenation of methyl (Z)-α-acetamidocinnammate, dimethyl itaconate (up to 99.9% ee’s) and methyl 2-acetamidoacrylate (up to 99.5% ee).

Asymmetric hydrogenation of α-keto phosphonates with chiral phosphine–phosphoramidite ligands

Rh-catalyzed asymmetric hydrogenation of challenging α-keto phosphonates has been developed. With a new chiral phosphine–phosphoramidite ligand, a wide range of α-keto phosphonates were hydrogenated to afford the corresponding (R)-α-hydroxy phosphonates with moderate to good enantioselectivities (up to 87% ee).

Chiral phosphine-phosphoramidite ligands for highly enantioselective hydrogenation of N-arylimines

The asymmetric hydrogenation of N-arylimines with the chiral phosphine-phosphoramidite ligand, (Sc,Sa)-PEAPhos 2b, has been developed, in which high turnover numbers and excellent enantioselectivity were achieved.

ChemInform Abstract: Chiral Phosphine—Phosphoramidite Ligands for Highly Efficient Ir‐Catalyzed Asymmetric Hydrogenation of Sterically Hindered N‐Arylimines.

AbstractThe new phosphoramidite efficiently promotes the Ir‐catalyzed asymmetric hydrogenation of a number of sterically hindered N‐arylimines.

Chiral Phosphine–Phosphoramidite Ligands for Highly Efficient Ir-Catalyzed Asymmetric Hydrogenation of Sterically Hindered N-Arylimines

A mild and general iridium-catalyzed, highly enantioselective hydrogenation of sterically hindered N-arylimines with a new H(8)-BINOL-derived phosphine-phosphoramidite ligand has been developed. The present catalytic system features high turnover numbers (up to 100000) and good to perfect enantioselectivities (up to 99% ee) for the hydrogenation of a variety of sterically hindered N-arylimines.

Progress on Unsymmetrical Hybrid Chiral Phosphine-phosphoramidite Ligands and Their Application in Asymmetric Catalytic Reactions

Unsymmetrical hybrid chiral phosphine-phosphoramidite ligands have the advantages of easy accessibility, modularity and stability toward air and moisture, which make them highly appealing for asymmetric catalysis. These ligands have been found widespread utility in asymmetric catalysis, such as hydrogenation, hydroformylation, allylic alkylation, hydrophosphorylation, [3 + 2] cycloaddition, 1,4-addition and 1,4-reduction. The types, synthesis and applications of chiral phosphine-phosphoramidite ligands are reviewed.

Chiral 1-phenylethylamine-derived phosphine-phosphoramidite ligands for highly enantioselective Rh-catalyzed hydrogenation of β-(acylamino)acrylates: significant effect of substituents on 3,3′-positions of binaphthyl moiety

A series of new chiral phosphine-phosphoramidite ligands with a 3,3'-substituted binaphthyl moiety were prepared from 1-phenylethylamine, and successfully applied in the Rh-catalyzed asymmetric hydrogenation of beta-(acylamino)-acrylates. The research disclosed that the substituents on the 3,3'-positions of binaphthyl moiety significantly influenced the enantioselectivity.

Asymmetric synthesis of chiral Roche ester and its derivatives via Rh-catalyzed enantioselective hydrogenation with chiral phosphine-phosphoramidite ligands

Methyl 3-hydroxy-2-methylpropionate, known as the Roche ester, was prepared with high enantioselectivity (up to 96.7% ee) via the Rh-catalyzed asymmetric hydrogenation of methyl 2-hydroxymethylacrylate with a chiral 1,2,3,4-tetrahydro-1-naphthylamine-derived phosphine-phosphoramidite ligand (THNAPhos 5a) even at a low catalyst loading (0.1 mol %). An investigation on the substrate scope revealed that the ester group present in the substrate has a significant effect on the enantioselectivity, and the substrate with the bulkier ester group tended to give lower enantioselectivity.

Novel chiral phosphine-phosphoramidite ligands derived from 1-naphthylamine for highly efficient Rh-catalyzed asymmetric hydrogenation

A new chiral phosphine-phosphoramidite ligand ( S)-HY-Phos 1 has been prepared from 1-naphthylamine via a two-step transformation, and successfully applied in the Rh-catalyzed asymmetric hydrogenation of various functionalized olefins, including α-(acetamido)cinnamates, enamides and α-enol ester phosphonates, in which up to 98% ee, 99% ee and 99% ee were achieved, respectively.

Me-AnilaPhos: a new chiral phosphine–phosphoramidite ligand for a highly efficient Rh-catalyzed asymmetric olefin hydrogenation

A cationic rhodium(I) complex with a novel chiral phosphine–phosphoramidite ligand based on 2-diphenylphosphino- N-methylaniline and R-BINOL moieties has been synthesized. The complex provided remarkably high activity and enantioselectivity in the asymmetric hydrogenation of methyl ( Z)-α-acetamidocinnamate (100% conversion after 10 min, 98% ee) and dimethyl itaconate (100% conversion after 26 min, 96% ee) under ambient conditions (1 bar hydrogen pressure, room temperature) using 1 mol % of the catalyst in dichloromethane as solvent. On the other hand, when hydrogenation was performed in methanol, both conversion and enantioselectivity were significantly diminished, due to the partial decomposition of the rhodium/phosphine–phosphoramidite complex.