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Electronic and Steric Effects of Atropisomeric Ligands SYNPHOS ® and DIFLUORPHOS ® vs. BINAPs in Rh(I)‐Catalyzed Asymmetric Pauson–Khand Reaction
Author(s) -
Kim Dong Eun,
Choi Choong,
Kim In Su,
Jeulin Séverine,
RatovelomananaVidal Virginie,
Genêt JeanPierre,
Jeong Nakcheol
Publication year - 2007
Publication title -
advanced synthesis and catalysis
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.541
H-Index - 155
eISSN - 1615-4169
pISSN - 1615-4150
DOI - 10.1002/adsc.200600623
Subject(s) - chemistry , binap , steric effects , alkyne , dihedral angle , electronic effect , phosphine , catalysis , medicinal chemistry , stereochemistry , enantioselective synthesis , photochemistry , organic chemistry , molecule , hydrogen bond
Abstract The electronic and steric effects of chiral biaryl diphosphine ligands on the Rh(I)‐catalyzed asymmetric Pauson–Khand type reaction were examined. We demonstrated that enantioselectivity and reaction yield were influenced by the electronic density on phosphorus, the dihedral angle of ligands and the electronic density of the alkyne substrate. Ligands bearing a narrower dihedral angle than Binap, such as Synphos ( L4 ) and Difluorphos ( L5 ), were found to increase substantially the enantioselectivity of the reaction, compared to Binap‐type ligands. Ligands having a deshielded phosphine, such as p ‐CF 3 ‐Binap ( L3 ) and Difluorphos ( L5 ) provided better enantioselectivity than Binap, with reduced formation of side products, especially with electron‐poor alkyne substrates.