Von Chinolin abgeleitete, chirale Phosphan/Phosphoramidit-Liganden (QUINAPHOS) für die asymmetrische Katalyse

Quinaphos and Dihydro‐Quinaphos Phosphine–Phosphoramidite Ligands for Asymmetric Hydrogenation

“…The two diastereomers ( R a , R c )‐ n Bu‐Quinaphos (( R a , R c )‐ 5 a ) and ( R a , S c )‐ n Bu‐Quinaphos (( R a , S c )‐ 5 a ) were separated by column chromatography and a strong cooperation between the two stereo‐elements was observed in asymmetric catalysis 9. The relative stereochemistry ( R a , R c )‐ 5 a was found to correspond to the matched diastereomer for the enantioselective Rh‐catalysed hydrogenation of olefins and led to excellent enantioselectivities and activities 9a…”

“…This hybrid phosphorus ligand and its derivatives were successfully applied in Rh‐catalysed asymmetric hydroformylation4 and hydrogenation5 reactions, as well as in Pd‐catalysed co‐polymerisation6 and hydrophosphorylation reactions 7. More recently, several phosphine–phosphoramidite ligands2, 8 have been synthesised and used in asymmetric hydrogenation9, 10 and hydroformylation9a, 11 reactions with the production of good to excellent enantioselectivities. In some cases, mixtures of monodentate chiral phosphoramidites and achiral phosphines can mimic the corresponding bidentate ligands.…”

“…In 2000, we reported the first example of a chiral phosphine–phosphoramidite ligand (Quinaphos) and showed the high potential of this class of ligands in asymmetric catalysis 9a. 10l, 13 Quinaphos is based on the 1,2‐dihydroquinoline backbone and is obtained through a modular synthetic approach as a diastereomeric mixture.…”

Highly Enantioselective Rh‐Catalysed Hydrogenation of 1‐Alkyl Vinyl Esters Using Phosphine–Phosphoramidite Ligands

“…[19] The QuinaPhos structure was reported as the first example of this class of ligands. [20] The 1-naphthyl-substituted QuinaPhos L1 and the related MatPhos [21] L2 (Figure 1) have been successfully ap-…”

“…plied subsequently in Rh-catalysed hydrogenations of functionalised alkenes, [20][21][22] Ru-catalysed hydrogenations of functionalised ketones, [21,23] and Ir-catalysed hydrogenation of 2-substituted-quinolines. [21] Considering the structural similarity to enamides, which could be hydrogenated with high enantioselectivities with Rh/phosphine-phosphoramidites catalysts, [21, 22b] we decided to examine (R a ,S c )-1-Naph-QuinaPhos L1 and (S a ,S c )-Mat-Phos L2 in the Rh-catalysed asymmetric hydrogenation of [ 1-alkyl vinyl esters.…”