568592-59-6Relevant academic research and scientific papers
Resolution and Diels - Alder catalysis with planar chiral arene-tethered ruthenium complexes
Faller,Fontaine, Philip P.
, p. 4132 - 4138 (2005)
Planar chiral arene-tethered ruthenium complexes were applied to the Diels-Alder reaction of methacrolein and cyclopentadiene, with enantiomeric excesses up to 70%. The influence of a chiral phosphoramidite ligand on the catalytic selectivity was examined, along with counterion effects. The potential of asymmetric activation using the mixture of diastereomers formed from a racemic tethered complex and an enantiopure phosphine directly in the catalysis was investigated.
Enantiofacial control of planar chiral arene ru complexes bearing Tropos biphenyl ligands
Aikawa, Kohsuke,Kaito, Isao,Mikami, Koichi
, p. 1482 - 1483 (2008/03/14)
A variety of planar chiral Ru-complexes bearing tropos ortho-substituted biphenyl ligands were synthesized. The planar chirality control of the Ru complexes by enantiopure (R)-H8DABN selectively gave the thermodynamically stable diastereomers via association of solvents employed. Copyright
Planar chirality in tethered η6:η1-(phosphinophenylenearene-P)ruthenium(II) complexes and their potential use as asymmetric catalysts
Faller,D'Alliessi, Darlene G.
, p. 2749 - 2757 (2008/10/08)
Reaction of 2-dicyclohexylphosphinobiphenyl with [(η6-benzene)RuCl2]2 yielded the tethered complex [Ru(η6:η1-dicyclohexylphosphinobiphenyl-P)Cl2 ], 1, rather than a bridge-splitting product, [(η6-benzene)Ru(L)Cl2], that is often observed. Treatment of [(η6-benzene)RuCl2]2 with 2-dicyclohexylphosphino-2′-(N,N-dimethylamino)biphenyl yielded the planar chiral, tethered complex [Ru(η6:η1-2-dicyclohexylphosphino-2-′-(N,N-d imethylamino)biphenyl-P)Cl2], 2. Abstraction of a chloride from 2 with AgSbF6 and treatment with PPh3 selectively gave the chiral-at-metal complex [anti-Ru(η6:η1-2-dicyclohexylphosphino-2′-(N ,N-dimethylamino)-biphenyl-P) (PPh3)Cl]SbF6, 3a, which underwent spontaneous resolution upon crystallization. The Me2N group is coplanar with the η6-phenyl ring in the cations and directs attack at the metal center, as well as determining the thermodynamic stability of anti versus syn epimers. The dication derived from enantiopure 3a catalyzed the Diels-Alder reaction of methacrolein and cyclopentadiene with modest (19-23%) enantioselectivity. Analogues of 2 and 3a containing 2-(dicyclohexylphosphino)-2′-methylbiphenyl were also prepared. We have found that epimerization at the metal center is slow in these compounds. Averaged NMR spectra at ambient temperatures are observed, however, due to rapid conformational interconversions that can be slowed at low temperature.
