29267-46-7Relevant articles and documents
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.
Synthesis and Characterization of Mono- and Tri-nuclear Ruthenium Complexes of 2,2'-Bis(diphenylphosphino)-1,1'-binaphthyl and Their Catalytic Activity
Mashima, Kazushi,Hino, Takahiro,Takaya, Hidemasa
, p. 2099 - 2108 (2007/10/02)
The structures of ruthenium(II) complexes formed in solution from Y (S)-3 (X, Y = halide and/or BF4-; binap = 2,2'-bis(diphenylphosphino)-1,1'-binaphthyl; arene = benzene or p-cymene) depend on the solvent.In acetonitrile-methanol (1:1) dicationic complexes X(Y) (S)-4 (X = Y = Cl a; X = Cl, Y = BF4 b; X = Y = Br c; or X = Y = I d) are predominantly formed, while monocationic species X (S)-6 (X = Cl a, Br b or I c) were observed in acetonitrile.These mono- and di-cationic species could not be isolated pure, while (S)-5 was isolated from (S)-4a or (S)-6a upon concentration of the reaction mixture.In methanol without donor molecules such as acetonitrile, cationic trinuclear complexes Y (S)-7 (X = Y = Cl a; X = Cl, Y = BF4 b or X = Y = Br c) were exclusively formed by heating at 60 deg C or UV irradiation of a solution of (S)-3.The structure of (S)-7 was characterized by spectral data and an X-ray crystallographic analysis of (S)-7b 12121, a = 26.328(5), b = 18.140(3), c = 26.374(4), Z = 4, R'= 0.083>.The relationship between the structure of the RuII(binap) complexes and their catalytic activities for asymmetric hydrogenation of methyl 3-oxobutanoate has been investigated.
