66875-70-5

Upstream product

• 108-05-4 vinyl acetate 
• 201230-82-2 carbon monoxide 
• 110773-72-3 (S)-lactaldehyde diethyl acetal O-acetate 

Downstream Products

• 945494-69-9 C₁₅H₂₀N₂O₃ 
• 945494-68-8 C₂₂H₁₉F₅N₂O₄ 

Relevant academic research and scientific papers

Effector enhanced enantioselective hydroformylation

In this communication, we report rhodium DIMPhos complexes with an integrated DIM-receptor that can bind carboxylate containing effectors and their application in the rhodium catalyzed hydroformylation reaction. The binding of chiral effectors in non-chiral [Rh(DIMPhos)] catalysts does not lead to enantioselective hydroformylation, but the binding of either achiral or chiral effectors can significantly enhance the enantioselectivity induced by the chiral Rh-metal complexes. For example, the supramolecular complex [Rh]/[1S?L3] displays high regio- and enantioselectivity in the hydroformylation of vinyl acetate (72% ee, and b/l >99), whereas in absence of this effector the ee is around 17%.

Tunable P-Chiral Bisdihydrobenzooxaphosphole Ligands for Enantioselective Hydroformylation

Air-stable and tunable chiral bisdihydrobenzooxaphosphole ligands (BIBOPs) were employed in rhodium-catalyzed asymmetric hydroformylation of various terminal olefins with excellent conversions (>99%), moderate-to-excellent enantioselectivities (up to 95:5 er), and branched to linear ratios (b:l) of up to 400.

Supramolecularly Regulated Ligands for Asymmetric Hydroformylations and Hydrogenations

Herein we report the use of polyether binders as regulation agents (RAs) to enhance the enantioselectivity of rhodium-catalyzed transformations. For reactions of diverse substrates mediated by rhodium complexes of the α,ω-bisphosphite-polyether ligands 1-5,a-d, the enantiomeric excess (ee) of hydroformylations was increased by up to 82 (substrate: vinyl benzoate, 96ee), and the ee value of hydrogenations was increased by up to 5 (substrate: N-(1-(naphthalene-1-yl)vinyl)acetamide, 78ee). The ligand design enabled the regulation of enantioselectivity by generation of an array of catalysts that simultaneously preserve the advantages of a privileged structure in asymmetric catalysis and offer geometrically close catalytic sites. The highest enantioselectivities in the hydroformylation of vinyl acetate with ligand 4b were achieved by using the Rb[B(3,5-(CF3)2C6H3)4] (RbBArF) as the RA. The enantioselective hydrogenation of the substrates 10 required the rhodium catalysts derived from bisphosphites 3a or 4a, either alone or in combination with different RAs (sodium, cesium, or (R,R)-bis(1-phenylethyl)ammonium salts). This design approach was supported by results from computational studies.

Asymmetric Hydroformylation of Heterocyclic Olefins Mediated by Supramolecularly Regulated Rhodium-Bisphosphite Complexes

Rhodium complexes derived from conformationally transformable α,ω-bisphosphite ligands combined with a suitable alkali metal BArF salt as a regulation agent (RA) provide high regio- and enantioselectivities in the asymmetric hydroformylation (AHF) of three heterocyclic olefins. The outcome of the AHF could be exquisitely regulated by choosing the appropriate RA with an increase in the ee, the reversal of the regioselectivity, or the complete suppression of one byproduct.

Enantiopure narrow bite-angle P-OP ligands: Synthesis and catalytic performance in asymmetric hydroformylations and hydrogenations

Herein is reported the preparation of a set of narrow bite-angle P-OP ligands the backbone of which contains a stereogenic carbon atom. The synthesis was based on a Corey-Bakshi-Shibata (CBS)-catalyzed asymmetric reduction of phosphomides. The structure of the resulting 1,1-P-OP ligands, which was selectively tuned through adequate combination of the configuration of the stereogenic carbon atom, its substituent, and the phosphite fragment, proved crucial for providing a rigid environment around the metal center, as evidenced by X-ray crystallography. These new ligands enabled very good catalytic properties in the Rh-mediated enantioselective hydrogenation and hydroformylation of challenging and model substrates (up to 99 % ee). Whereas for asymmetric hydrogenation the optimal P-OP ligand depended on the substrate, for hydroformylation, a single ligand was the highest-performing one for almost all studied substrates: it contains an R-configured stereogenic carbon atom between the two phosphorus ligating groups, and an S-configured 3,3′-diphenyl-substituted biaryl unit. Ligand design: Narrow-bite-angle P-OP ligands incorporating a stereogenic carbon atom in their backbone have been synthesized by Corey-Bakshi-Shibata (CBS)-catalyzed asymmetric reduction of the corresponding intermediates followed by O-phosphorylation. Rhodium complexes of these ligands provided very good catalytic performance in hydroformylations and hydrogenations (see scheme).

Easily accessible and highly tunable bisphosphine ligands for asymmetric hydroformylation of terminal and internal alkenes

An efficient methodology for synthesizing a small library of easily tunable and sterically bulky ligands for asymmetric hydroformylation (AHF) has been reported. Five groups of alkene substrates have been tested with excellent conversions, moderate-to-excellent regio- and enantioselectivities. Among the best result of the reported literature, application of ligand 1 c in the highly selective AHF of the challenging substrate 2,5-dihydrofuran yielded almost one isomer in up to 99 % conversion along with enantiomeric excesses (ee) of up to 92 %. Highly enantioselective AHF of dihydropyrrole substrates is achieved using the same ligand, with up to 95 % ee and up to >1:50 β-isomer/α- isomer ratio. The simpler the better! An efficient method for the easy and tunable synthesis of a series of asymmetric hydroformylation (AHF) ligands from low-cost, commercially available starting materials has been reported. These ligands can give excellent conversions and moderate to excellent regio- and enantioselectivities for a broad range of mono- and disubstituted alkenes with a low catalyst loading (substrate-to-catalyst ratios (S/C) of 1000:1 to 3000:1).

Immobilized bisdiazaphospholane catalysts for asymmetric hydroformylation

Condensation reactions of enantiopure bis-3,4-diazaphospholanes (BDPs) that are functionalized with carboxylic acids enable covalent attachment to bead and silica supports. Exposure of tethered BDPs to the hydroformylation catalyst precursor, Rh(acac)(CO)2, yields catalysts for immobilized asymmetric hydroformylation (iAHF) of prochiral alkenes. Compared with homogeneous catalysts, catalysts immobilized on Tentagel resins exhibit similarly high regioselectivity and enantioselectivity. When corrected for apparent catalyst loading, the activity of the immobilized catalysts approaches that of the homogeneous analogues. Excellent recyclability with trace levels of rhodium leaching are observed in batch and flow reactor conditions. Silica-bound catalysts exhibit poorer enantioselectivities.

1,1-P-OP ligands with P-stereogenic phosphino groups in asymmetric hydrogenations and hydroformylations

A new series of narrow-bite-angle phosphine-phosphite (1,1-P-OP) ligands (3a-d) has been efficiently prepared from the enantiopure (SP)-tert- butyl(hydroxymethyl)methylphosphino borane complex 1, a crucial intermediate. The catalytic performance of the ligands in Rh-mediated asymmetric hydrogenations and hydroformylations is described. The corresponding rhodium complexes provided excellent efficiencies (full conversion in all cases) and high enantioselectivities (up to 98% ee) for the asymmetric hydrogenation of structurally diverse functionalized alkenes. Furthermore, rhodium catalysts derived from these 1,1-P-OP ligands were highly active and gave excellent regioselectivities (branched/linear product ratios of up to 97/3) and moderate enantioselectivities in the hydroformylation of different terminal olefins.

Small bite-angle P-OP ligands for asymmetric hydroformylation and hydrogenation

A series of small bite-angle phosphine-phosphite (P-OP) ligands have been synthesized by a two-step method. The key intermediate was prepared by an unprecedented asymmetric carbonyl reduction of a phosphamide using the CBS (Corey-Bakshi-Shibata) catalyst. The topology of these ligands (a configurationally stable stereogenic carbon with two heteroatom substituents) and their small bite-angle (created by the close proximity of the two ligating groups to the metal center) together provide a rigid asymmetric environment around this center, enabling high stereoselectivity in hydroformylations and hydrogenations of standard substrates.

Bis(phosphite) ligands with distal regulation: Application in rhodium-mediated asymmetric hydroformylations

Small amounts of achiral polyether binders are employed to enhance the enantioselectivity of the hydroformylation of an array of diversely substituted substrates (increase of up to 62 % ee for vinyl acetate) mediated by chiral rhodium complexes derived from the α,ω-bis(phosphite)-polyether ligands 1. To the best of our knowledge, this study represents an unprecedented successful example of the positive regulation of enantioselectivity in hydroformylations.