124150-22-7Relevant articles and documents
Enantioselective hydrogenation of β-keto esters catalyzed by P-chiral bis(dialkylphosphino)ethanes-Ru(II)
Yamano, Toru,Taya, Naohiro,Kawada, Mitsuru,Huang, Taisheng,Imamoto, Tsuneo
, p. 2577 - 2580 (2007/10/03)
Asymmetric hydrogenation of keto esters using a BisP*-RuBr2 catalyst is reported. High enantioselectivities up to 98% were achieved in the hydrogenation of β-keto esters.
Stereo- and chemoselective transfer hydrogenation of carbonyl groups with RuCl2(PPh3)3 and BINAP-Ru as catalysts and et3NH+H2PO2-·1,5H 2O as a hydrogen donor
Khai, Bui The,Arcelli, Antonio
, p. 6599 - 6602 (2007/10/03)
Using Et3NH+H2PO2-.1.5 H2O as a hydrogen donor, the RuCl2(Ph3P)3, RuCl2(PPh3)3 / C and BINAP-Ru proved highly active catalysts for transfer hydrogenation of ketones under milder conditions than other hydrogen donors. 2-Methyl-, 2-chloro-, 2-(ethoxycarbonyl)cyclohexanones and -cyclopentanones were reduced to the less stable axial alcohols in excellent diastereoisomeric excess (de: 90-100%), and the carbonyl group of α,β-unsaturated ketones was selectively reduced, in contrast with other hydrogen donors the C=C bond was reduced. Copyright
New Class of Chiral Diphosphine Ligands for Highly Efficient Transition Metal-Catalyzed Stereoselective Reactions: The Bis(diphenylphosphino) Five-membered Biheteroaryls
Benincori, Tiziana,Brenna, Elisabetta,Sannicolo, Franco,Trimarco, Licia,Antognazza, Patrizia,et al.
, p. 6244 - 6251 (2007/10/03)
The synthesis and application of three examples of a new class of chiral (C2) atropisomeric diphosphines characterized by two interconnected five-membered heteroaromatic rings, with hindered rotation around the interanular bond, are described.Optically pure (+)- and (-)-2,2'-bis(diphenylphosphino)-4,4',6,6'-tetramethyl-3,3'-bibenzothiophene (tetraMe-bitianp) (1a) and the parent unsubstituted system (+)- and (-)-bitianp (1b) were synthesized.They were found to be optically stable at 100 deg C and were successfully employed as ligands in the Ru(II)-catalyzed hydrogenation of α- and β-oxo esters to the corresponding α- and β-hydroxy esters and in the hydrogenation of olefinic substrates.The optical and chemical yields were comparable with those reported for the same Ru(II)-binap-catalyzed reactions carried out under the same experimental conditions.The 2,2'-bis(diphenylphosphino)-3,3'-bibenzofuran (1c), the oxygenated analogue of bitianp, was found to be configurationally unstable at room temperature.Complete structural X-ray elucidation of the Pd complexes of 1a-c is reported.The advantages of these biheteroaromatic ligands over the classical biaryl systems are discussed.
(Diphenylphosphino)-biheteroaryls: the First Example of a New Class of Chiral Atropisomeric Chelating Diphosphine Ligands for Transition Metal Catalysed Stereoselective Reactions
Benincori, Tiziana,Brenna, Elisabetta,Sannicolo, Franco,Trimarco, Licia,Antognazza, Patrizia,Cesarotti, Edoardo
, p. 685 - 686 (2007/10/02)
Ruthenium(II) dichloride complexes with (+)- and (-)-2,2'-bis(diphenylphosphino)-4,4',6,6'-tetramethyl-3,3'-bibenzothiophene (1a), new chiral atropisomeric heterocyclic ligands, reduce α- and β-oxoesters to α- and β-hydroxyesters with an enantiomeric purity comparable, if not higher, to that reported for binap under the same experimental conditions.
65. Homogeneous and Heterogeneous Asymmetric Reactions. Part 5. Diastereoselective and Enantioselective Hydrogenation of Cyclic β-Keto Esters on Modified Raney-Nickel Catalysts
Wittmann, Gyula,Goendoes, Gyoergy,Bartok, Mihaly
, p. 635 - 639 (2007/10/02)
The hydrogenations of methyl 2-oxocyclopentanecarboxylate (1), ethyl 2-oxocyclohexanecarboxylate (3), and 2-methylcyclohexanone (5) on unmodified Raney-Ni catalyst lead predominantly to the formation of the cis-hydroxy diastereoisomers of 2, 4, and 6, respectively (Scheme 2).In the asymmetric hydrogenations on catalysts modified with chiral tartaric acid (R,R)-C4H6O6/Raney-Ni and (R,R)-C4H6O6/NaBr/Raney-Ni), the predominance of the cis-isomer increases significantly.The hydrogenations of β-keto esters 1 and 3 proceed with an enantioselectivity of 10-15percent on the modified catalysts, while the similar hydrogenation of 5 yields optically inactive 6.The (1S,2R)-enantiomers of the cis-isomers of 2 and 4 are formed in larger quantity, whereas the (1R,2R)-enantiomers of the corresponding trans-isomers predominate (Scheme 1).The enantioselective formation of trans-2 and trans-4 can be interpreted mainly in terms of the asymmetric hydrogenation of cyclic β-keto esters through the keto form, while that of the corresponding cis-hydroxy esters proceeds through the enol form.
