Rhodium-Catalyzed Enantioselective Hydrogenation of Unsaturated Phosphonates by ClickFerrophos Ligands

Ni-Catalyzed Asymmetric Hydrogenation of α-Substituted α,β-Unsaturated Phosphine Oxides/Phosphonates/Phosphoric Acids

Efficient Ni/(S,S)-Ph-BPE-catalyzed asymmetric hydrogenation of α-substituted α,β-unsaturated phosphine oxides/phosphonates/phosphoric acids has been successfully developed, and a wide range of chiral α-substituted phosphines hydrogenation products were obtained in generally high yields with excellent enantioselective control (92%-99% yields, 84%->99% ee). This method features a cheap transition metal nickel catalytic system, high functional group tolerance, wide substrate scope generality, and excellent enantioselectivity. A plausible catalytic cycle was proposed for this asymmetric hydrogenation according to the results of deuterium-labeling experiments.

Enantioselective Synthesis of Chiral Phosphonates via Rh/f-spiroPhos Catalyzed Asymmetric Hydrogenation of β,β-Disubstituted Unsaturated Phosphonates

The first asymmetric hydrogenation of β,β-diaryl unsaturated phosphonates has been realized for synthesis of β,β-diaryl chiral phosphonates with excellent enantioselectivities (up to 99.9% ee) catalyzed by the Rh-(R,R)-f-spiroPhos complex. Furthermore, this catalyst also exhibits comparably excellent performance for β-aryl-β-alkyl unsaturated phosphonates providing the corresponding chiral phosphonates with up to 99.9% ee values. This methodology provides a straightforward access to asymmetric synthesis of chiral phosphonates.

Inverting External Asymmetric Induction via Selective Energy Transfer Catalysis: A Strategy to β-Chiral Phosphonate Antipodes

Enantiodivergent, catalytic reduction of activated alkenes relays stereochemical information encoded in the antipodal chiral catalysts to the pro-chiral substrate. Although powerful, the strategy remains vulnerable to costs and availability of sourcing both catalyst enantiomers. Herein, a stereodivergent hydrogenation of α,β-unsaturated phosphonates is disclosed using a single enantiomer of the catalyst. This enables generation of the R- or S-configured β-chiral phosphonate with equal and opposite selectivity. Enantiodivergence is regulated at the substrate level through the development of a facile E → Z isomerisation. This has been enabled for the first time by selective energy transfer catalysis using anthracene as an inexpensive organic photosensitiser. Synthetically valuable in its own right, this process enables subsequent RhI -mediated stereospecific hydrogenation to generate both enantiomers of the product using only the S-catalyst (up to 99:1 and 3:97 e.r.). This strategy out-competes the selectivities observed with the E-substrate and the R-catalyst.

Asymmetric Vinylogous Aldol-type Reactions of Aldehydes with Allyl Phosphonate and Sulfone

Two catalytic asymmetric vinylogous aldol-type reactions of aldehydes with allyl phosphonate and allyl sulfone have been uncovered in good to high yields for the first time. The bulky ligand-(R)-DTBM-SEGPHOS-was found to be the key to perfectly control both regio- and enantioselectivities. Transformations of the vinylogous products (including Horner-Wadsworth-Emmons and Julia olefinations) were successfully realized by virtue of the phosphonate and sulfone moieties. Moreover, the present methodology was successfully applied in the asymmetric synthesis of natural products.

Base-mediated 1,6-conjugate addition of the Seyferth-Gilbert reagent to para-quinone methides

A 1,6-conjugate addition reaction of the Seyferth-Gilbert reagent (SGR) to p-quinone methides is reported. This base-mediated protocol allows rapid access to diarylmethylated diazomethylphosphonates. The reaction proceeds under mild basic conditions, making it a practical approach for the synthesis of diarylmethylated diazomethylphosphonates with a broad substrate scope. Interestingly, the treatment of the conjugate adduct with a catalytic amount of rhodium acetate resulted in the 1,2-aryl migration of the rhodium carbenoid intermediate to generate the corresponding 1,2-diaryl alkenylphosphonates in excellent yields.

Rhodium-catalyzed enantioselective hydrogenation of α-amino acrylonitriles: an efficient approach to synthesizing chiral α-amino nitriles

An efficient asymmetric hydrogenation of α-amino acrylonitriles has been achieved, affording chiral α-amino nitriles in excellent yields and enantioselectivities regardless of the cis–trans configuration of α-amino acrylonitriles.

Applications of α-phosphonovinyl tosylates in the synthesis of α-arylethenylphosphonates via Suzuki-Miyaura cross-coupling reactions

It has been demonstrated for the first time that α-phosphonovinyl tosylates could efficiently couple with a range of arylboronic acids to access α-arylethenylphosphonates. The unprecedented procedure exhibits excellent functional group tolerance, giving the terminal vinylphosphonates in good to excellent isolated yields (60-99%) under mild reaction conditions.

Decarboxylative functionalization of cinnamic acids

Decarboxylative functionalization of α,β-unsaturated carboxylic acids is an emerging area that has been developed significantly in recent years.

Cu-catalyzed asymmetric allylic alkylation of phosphonates and phosphine oxides with Grignard reagents

An efficient and highly enantioselective copper-catalyzed allylic alkylation of phosphonates and phosphine oxides with Grignard reagents and Taniaphos or phosphoramidites as chiral ligands is reported. Transformation of these products leads to a variety of new phosphorus-containing chiral intermediates.