New derivatives of the Quinaphos ligands and the related Dihydro-Quinaphos ligands based on the more flexible 1,2,3,4-tetrahydroquinoline backbone have been prepared and fully characterised. A general and straightforward separation protocol was devised, which allowed for the gram-scale isolation of the R(a),S(c) and S(a),R(c) diastereomers. These new phosphine-phosphoramidite ligands have been applied in the Rh-catalysed asymmetric hydrogenation of functionalised olefins with the achievement of excellent enantioselectivities (> or = 99%) in most cases and turnover frequency (TOF) values of up to > or = 20,000 h(-1). These results substantiate the practical utility of readily accessible Quinaphos-type ligands, which belong to the most active and selective category of ligands for Rh-catalysed hydrogenation known to date.
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http://dx.doi.org/10.1002/chem.201000063 | DOI Listing |
Org Lett
January 2025
Dalian Institute of Chemical Physics, Chinese Academy of Sciences, 457 Zhongshan Road, Dalian 116023, China.
A series of chiral hybrid diphosphorus ligands incorporating a conformationally flexible tropos diphenylmethane-based phosphoramidite unit have been developed and evaluated in the Rh-catalyzed asymmetric hydrogenation of 2-(1-arylvinyl)anilides and α-enamides, leading to up to >99% yield and 99% enantiomeric excess. Preliminary results from comparative studies showcased the extraordinary catalytic performance of these chiral tropos phosphine-phosphoramidite ligands, with a competency essentially superior to those of well-established ligands with a regular rigid backbone.
View Article and Find Full Text PDFAngew Chem Int Ed Engl
December 2022
Key Laboratory of Organosilicon Chemistry and Material Technology of Ministry of Education, and Key Laboratory of Organosilicon Material Technology of Zhejiang Province, College of Material, Chemistry and Chemical Engineering, Hangzhou Normal University, No. 2318, Yuhangtang Road, Hangzhou, 311121, P. R. China.
Strategies on the construction of enantiomerically pure silicon-stereogenic silanes generally relies on desymmetrization of prochiral and symmetric substrates. However, dynamic kinetic asymmetric transformations of organosilicon compounds have remained underdeveloped and unforeseen owing to a lack of an effective method for deracemization of the static silicon stereocenters. Here we report the first Rh-catalyzed dynamic kinetic asymmetric intramolecular hydrosilylation (DyKAH) with "silicon-centered" racemic hydrosilanes that enables the facile preparation of silicon-stereogenic benzosiloles in good yields and excellent enantioselectivities.
View Article and Find Full Text PDFOrg Lett
October 2021
Dalian Institute of Chemical Physics, Chinese Academy of Sciences, 457 Zhongshan Road, Dalian 116023, China.
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 -tertiary benzylic stereocenter.
View Article and Find Full Text PDFOrg Lett
December 2019
Dalian Institute of Chemical Physics, Chinese Academy of Sciences , Dalian 116023 , China.
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 ()-3,3'-dimethyl H-naphthyl moiety and ()-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 -diastereoselectivity.
View Article and Find Full Text PDFOrg Lett
November 2019
Dalian Institute of Chemical Physics, Chinese Academy of Sciences , 457 Zhongshan Road , Dalian 116023 , China.
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).
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