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Relevant academic research and scientific papers

Highly enantioselective hydrogenation of α-dehydroamino esters and itaconates with triphosphorous bidentate ligands and the unprecedented solvent effect thereof

(Chemical Equation Presented) An X-ray diffraction experiment revealed an interesting triphosphorous bidentate coordination in a Pd(II) complex of a phosphine-phosphoramidite ligand 1, which showed excellent enantioselectivity (up to 99.4% ee) in Rh-catalyzed hydrogenation of α-dehydroamino esters in acetone. A dramatic solvent effect was found in the hydrogenation of itaconates, which induces opposite chiralities of the product with the same catalytic system by the use of different solvents (e.g., 99.6% ee (R) in TFE vs 71.2% ee (S) in methyl ethyl ketone).

Chiral bisphospholane ligands (Me-ketalphos): Synthesis of their Rh(I) complexes and applications in asymmetric hydrogenation

Rhodium complexes of functionalized bisphospholane ligands (S,S,S,S-Me-ketalphos) 1 and (R,S,S,R-Me-ketalphos) 2 have been used as catalyst precursors for the asymmetric hydrogenation of several different types of functionalized olefins and have achieved

Synthesis of novel BINOL-derived chiral bisphosphorus ligands and their application in catalytic asymmetric hydrogenation

Some novel ortho-substituted BINOL-derived bisphosphorus ligands (o-BINAPO and o-NAPHOS) were synthesis from readily available (S)-BINOL; these ligands showed excellent enantioselectivities (up to 99% ee) in Rh(I)-catalyzed asymmetric hydrogenation of fun

Mechanistically Guided One Pot Synthesis of Phosphine-Phosphite and Its Implication in Asymmetric Hydrogenation

Although hybrid bidentate ligands are known to yield highly enantioselective products in asymmetric hydrogenation (AH), synthesis of these ligands is an arduous process. Herein, a one pot, atom-economic synthesis of a hybrid phosphine-phosphite (L1) is reported. After understanding the reactivity difference between an O-nucleophile versus C-nucleophile, one pot synthesis of Senphos (L1) was achieved (72 %). When L1 was treated with [Rh], 31P NMR revealed bidentate coordination to Rh. Senphos, in the presence of rhodium, catalyzes the AH of Methyl-2-acetamido-3-phenylacrylate and discloses an unprecedented turn over frequency of 2289, along with excellent enantio-selectivity (92 %). The generality is demonstrated by hydrogenating an array of alkenes. The AH operates under mild conditions of 1–2 bar H2 pressure, at room temperature. The practical relevance of L1 is demonstrated by scaling-up the reaction to 1 g and by synthesizing DOPA, a drug widely employed for the treatment of Parkinson's disease. Computational insights indicate that the R isomer is preferred by 3.8 kcal/mol over the S isomer.

Topology-Based Functionalization of Robust Chiral Zr-Based Metal-Organic Frameworks for Catalytic Enantioselective Hydrogenation

The design and development of robust and porous supported catalysts with high activity and selectivity is extremely significant but very challenging for eco-friendly synthesis of fine chemicals and pharmaceuticals. We report here the design and synthesis of highly stable chiral Zr(IV)-based MOFs with different topologies to support Ir complexes and demonstrate their network structures-dependent asymmetric catalytic performance. Guided by the modulated synthesis and isoreticular expansion strategy, five chiral Zr-MOFs with a flu or ith topology are constructed from enantiopure 1,1′-biphenol-derived tetracarboxylate linkers and Zr6, Zr9, or Zr12 clusters. The obtained MOFs all show high chemical stability in boiling water, strongly acidic, and weakly basic aqueous solutions. The two flu MOFs featuring the dihydroxyl groups of biphenol in open and large cages, after sequential postsynthetic modification with P(NMe2)3 and [Ir(COD)Cl]2, can be highly efficient and recyclable heterogeneous catalysts for hydrogenation of α-dehydroamino acid esters with up to 98% ee, whereas the three ith MOFs featuring the dihydroxyl groups in small cages cannot be installed with P(NMe2)3 to support the Ir complex. Incorporation of Ir-phosphorus catalysts into Zr-MOFs leads to great enhancement of their chemical stability, durability, and even stereoselectivity. This work therefore not only advances Zr-MOFs as stable supports for labile metal catalysts for heterogeneous asymmetric catalysis but also provides a new insight into how highly active chiral centers can result due to the framework topology.

A supramolecularly tunable chiral diphosphine ligand: Application to Rh and Ir-catalyzed enantioselective hydrogenation

A supramolecularly tunable chiral bisphosphine ligand bearing two pyridyl-containing crown ethers, (-) or (+)-Xyl-P16C6-Phos, was fabricated and utilized in the Rh-catalyzed asymmetric hydrogenation of α-dehydroamino acid esters and Ir-catalyzed asymmetric hydrogenation of quinolines in high yields with excellent enantioselectivities (90-99% ee). Up to a 22% enhancement in enantioselectivity was achieved by the addition of certain amounts of alkali ions (Li+, Na+ or K+), which could be selectively recognized and effectively complexed by the crown ethers on the chiral Xyl-P16C6-Phos.

Model containing pyridine base crown ether chiral bis-phosphorus ligand and its in asymmetric catalytic application of the catalyst in the reaction (by machine translation)

This invention relates to model containing pyridine base crown ether chiral bis-phosphorus ligand and its application of symmetrical catalytic reaction. Chiral bis-phosphorus ligand and intermediates containing pyridine base crown ether single phosphorus ligand the structural formula of (I) are respectively shown as the following formula, formula (I '). These chiral bis-phosphorus ligand of the transition metal complexes can be used as catalyst for asymmetric reactions, containing pyridine base crown ether of the invention the chiral bis-phosphorus ligand it is a kind of novel chiral ligand capable of regulating, by using different alkali metal ion, alkaline earth metal ion, rare-earth metal ion, ammonium salt or organic amine salt such as a crown ether, on the object with the ligand complex, the catalyst can be realized the space structure and electronic nature of the regulation and control. This kind of the alkali metal ion complexation assembled containing pyridine base crown ether chiral double-phosphorus ligand transition metal (Rh and Ir) complexes in catalytic hydrogenation reaction demonstrate excellent catalytic activity and good stereoselectivity. (by machine translation)

Chiral Rh phosphine-phosphite catalysts immobilized on ionic resins for the enantioselective hydrogenation of olefins in water

The asymmetric hydrogenation of prochiral enamides with Rh complexes bearing chiral phosphine-phosphite ligands (P-OP) supported on sulphonated polystyrene resins has been studied. The complexes have been supported by simple treatment of preformed [Rh(dio

Novel, tunable, and efficient chiral bisdihydrobenzooxaphosphole ligands for asymmetric hydrogenation

"Chemical Equation Presented" A series of novel, efficient, air-stable, and tunable chiral bisdihydrobenzooxaphosphole ligands (BIBOPs) were developed for rhodium-catalyzed hydrogenations of various functionalized olefins such as α-ary lenam ides, α-(acylamino)acrylic acid derivatives, β-(acylamino)acrylates, and dimethyl itaconate with excellent enantioselectivities (up to 99% ee) and reactivities (up to 2000 TON)

Practical by ligand design: A new class of monodentate phosphoramidite ligands for rhodium-catalyzed enantioselective hydrogenations

A new class of low-cost and easy-to-prepare monodentate phosphoramidite ligands (Cydam-Phos) has been developed from readily accessible and cheap trans-1,2-diaminocyclohexane as starting material through a three-step transformation. This type of ligands exhibited excellent enantioseletivities and high activities in rhodium(I)-catalyzed asymmetric hydrogenations of dehydro-α-amino acid methyl esters 9 (ee: 96.2-99.8%) and acetylenamides 11 (91.8-98.8%). The remarkable substituent effects exhibited by the ligands on the enantioselective control of the catalysis are rationalized on the basis of molecular structure of the catalyst precursor.