studies on this route for forming pincercomplexes revealed the intermediacy of [4-tert-butyl-2,6-bis(N-alkylimino)phenyl]chlorobis(triphenylphosphine)palladium which is in equilibrium with the corresponding NCN pincercomplexes via coordination/dissociation of the intramolecular imino groups and triphenylphosphine ligands. A series of chiral NCN pincercomplexes bearing pyrroloimidazolone units as
Asymmetric aldol reaction of 2-cyanopropionates catalyzed by a trans-chelating chiral diphosphine–rhodium(I) complex: highly enantioselective construction of quaternary chiral carbon centers at α-positions of nitriles
作者:Ryoichi Kuwano、Hiroshi Miyazaki、Yoshihiko Ito*
DOI:10.1016/s0022-328x(00)00049-8
日期:2000.5
The aldolreaction of 2-cyanopropionates with aldehydes proceeded under neutral conditions in the presence of a catalytic amount of the rhodium complex generated in situ from Rh(acac)(CO)2 and triphenylphosphine, to give the corresponding β-hydroxy-α-cyanocarboxylates bearing a quaternary chiral carbon center at the α-position of the cyano group. A high degree of asymmetric induction for the aldol reaction
Novel Asymmetric Michael Addition of α-Cyanopropionates to Acrolein by the Use of a Bis(oxazolinyl)phenylstannane-Derived Rhodium(III) Complex as a Chiral Lewis Acid Catalyst
rhodium complex prepared in situ by simply mixing [[RhCl(c-octene)2]2] and [(Phebox)SnMe3] (1) (Phebox = 2,6-bis(oxazolinyl)phenyl) was found to serve as an efficient catalyst for the asymmetricMichaeladdition of alpha-cyanopropionates (4) to acrolein under mild and neutral conditions. In the present catalytic system, both the temperature of catalyst preparation and the order of the addition of the
Development of Chiral Pincer Palladium Complexes Bearing a Pyrroloimidazolone Unit. Catalytic Use for Asymmetric Michael Addition
作者:Kazuhiro Takenaka、Yasuhiro Uozumi
DOI:10.1021/ol0494515
日期:2004.5.1
Novel pincer palladiumcomplexes having chiral hexahydro-1H-pyrrolo[1,2-c]imidazolone groups were designed and prepared. Catalyticasymmetric Michael addition of isopropyl 2-cyanopropionate to ethyl vinyl ketone was catalyzed by the chiral pincer palladiumcomplex to give isopropyl 2-cyano-2-methyl-5-oxoheptanoate with high enantioselectivity (up to 83% ee). [structure: see text]
Asymmetric aldol reaction of 2-cyanopropionates catalysed by trans-chelating chiral diphosphine ligand TRAP–rhodium(I) complex
作者:Ryoichi Kuwano
DOI:10.1039/a706662g
日期:——
trans-Chelating chiral diphosphine TRAP ligands bearing P-aromatic groups are effective for RhI-catalysed asymmetric aldol reaction of 2-cyanopropionates with an aldehyde to give the corresponding aldol adduct with up to 93% ee.