Yasuzo Uchida

Oxidative additions to nickel(0): preparation and properties of a new series of arylnickel(II) complexes

Abstract A new series of stable arylnickel(II) complexes of the type (PPh3)2Ni(aryl)X (X=Cl, Br) were prepared by oxidative additions of aryl halides to Ni(PPh3)4, where aryl is not only an ortho-substituted, but also phenyl or a meta- or para-substituted aromatic ligand. The order of decrease in their thermal stability was o-tolyl > p-chlorophenyl > m- or p-tolyl.

Reactions of palldium(II) compounds with carbon monoxide in alcohol/amine systems : a new route to palladium(O) carbonyl and carboalkoxy-palladium(II) complexes

Abstract Palladium(O) carbonyl complexes, Pd(CO)(PPh 3 ) 3 Pd 3 (CO) 3 (PPh 3 ) 3 and Pd 3 (CO) 3 (PPh 3 ) 4 , can conveniently be prepared by the reaction of (PPh 3 ) 2 PdCl 2 with carbon monoxide at room temperature in methanol/amine systems involving primary and secondary amines such as diethylamine and cyclohexylamine. These carbonyl complexes are interconvertible under suitable conditions. On the other hand, use of tertiary amine such as triethylamine and tri-n-butylamine in place of the above amines give selectively a carbomethoxy complex (PPh 3 ) 2 PdCl(COOCH 3 ).

Carboxymethylation of Organic Halides by Palladium Complexes under Mild Conditions

Palladium complexes, Pd(CO)(PPh3)3, Pd3(CO)3(PPh3)4, Pd3(CO)3(PPh3)3, and PdCl2(PPh3)2 were found to be excellent catalysts for the carboxymethylation of various organic halides under very mild conditions. The carboxymethylation reaction is considered to proceed via acyl complexes as the intermediates.

Synthesis and properties of stable palladium(0) carbonyl complexes containing triphenylphosphine

Abstract The synthesis and properties of the stable zerovalent palladium carbonyl complexes are described. Mononuclear Pd(CO)(PPh 3 ) 3 has been prepared in good yield by two different routes i.e., the reaction of palladium(II) acetylacetonate with triethylaluminum and the reaction of dichloro-bis(triphenylphosphine)palladium(II) with sodium borohydride, both in the presence of triphenylphosphine under carbon monoxide. The trinuclear cluster [Pd 3 (CO) 3 (PPh 3 ) 3 ] has been obtained by the reaction between equimolar quantities of palladium(II) acetylacetonate and triphenylphosphine. Another trinuclear cluster complex [Pd 3 (CO) 3 (PPh 3 ) 4 ] has been prepared by heating Pd(CO)(PPh 3 ) 3 in ether, an equilibrium between these two complexes being observed in solution. Oxidative addition reactions of Pd(CO)(PPh 3 ) 3 with methyliodide, allylchloride, and vinyl chloride gave the corresponding acyl complexes of the type trans -PdX(COR)(PPh 3 ) 2 .

Asymmetric hydrogenation of 3,5-Dioxoesters catalyzed by Ru-binap complex: A short step asymmetric synthesis of 6-substituted 5,6-dihydro-2-pyrones

Abstract Asymmetric hydrogenation of 3,5-dioxoesters 1a-c using Ru2Cl4((R) or (S)-binap)2(NEt3) as the catalyst gave dominantly anti 3,5-dihydroxyesters 2, which were then converted into unsaturated lactones 5a-b (ca. 80% e.e.). The pathway of the hydrogenation reaction was also investigated by asymmetric hydrogenation of (R)- or (S)-5-hydroxy-3-oxoester 8a-c. It was revealed that the Ru-binap catalyzed hydrogenation of 1a-b proceed dominantly via the β-diketone mode. A convenient asymmetric synthesis of hydroxylactone 3c and unsaturated lactone 5c was presented.

Homogeneous multimetallic catalysts: Part 6. Hydroformylation and hydroesterification of olefins by homogeneous cobalt-ruthenium bimetallic catalysts

Abstract The Co 2 (CO) 8 -Ru 3 (CO) 12 bimetallic systems showed high catalytic activity for hydroformylation of olefins such as cyclohexene, 1-hexene and styrene, compared with Co 2 (CO) 6 or Ru 3 (CO) 12 alone. The hydroformylation by the bimetallic catalysts was remarkably influenced by the nature of the solvent used, and alcohols such as methanol and ethanol were the best among the solvents employed. Thus, the initial rate of the hydroformylation of cyclohexene with the Co 2 (CO) 8 -Ru 3 (CO) 12 catalyst (Ru:Co=1:1) in methanol was nineteen times faster than that with Co 2 (CO) 8 , if the reaction was performed at 110 °C under CO:H 2 pressure (40:40 kg cm −2 initial pressure at room temperature). The bimetallic systems were also effective for the hydroesterification of cyclohexene. The synergistic effect for cobalt and ruthenium on hydroformylation and hydroesterification is discussed.

Ruthenium (II)-BINAP complex catalyzed asymmetric hydrogenation of unsaturated dicarboxylic acids

Abstract Asymmetric hydrogenation of unsaturated dicarboxylic acids employing ruthenium-BINAP complexes as catalyst gave optically active 2-alkylsuccinic acids with high enantioselectivities.

Asymmetric hydrogenation of 2-fluoro-2-alkenoic acids catalyzed by Ru-binap complexes: A convenient access to optically active 2-fluoroalkanoic acids☆

Abstract Asymmetric hydrogenation of ( Z )-2-fluoro-2-alkenoic acid, ( Z )- 1a and ( Z )- 1b , was carried out, employing Ru 2 Cl 4 (binap) 2 (NEt 3 ) as a catalyst to afford 2-fluoroalkanoic acids, 2a and 2b , having high enantiomeric purities (up to 90% e.e.) When the ( R )-binap catalyst was used, not only ( Z )- 1a but ( E )- 1a was hydrogenated smoothly to give ( R )- 2a with comparable asymmetric induction.

Asymmetric hydrogenation of prochiral carboxylic acids catalyzed by the five-coordinate ruthenium(II)-hydride complex [RuH(binap)2]PF6 (binap = (R)- or (S)-2,2'-bis(diphenylphosphino)-1,1'-binaphthyl)

Abstract The five-coordinate complex [RuH(binap)2]PF6 (I, binap = (R)- or (S)-2,2′-bis(diphenylphosphino)-1,1′-binaphthyl) has been found to have sufficient catalytic activity for asymmetric hydrogenation of itaconic acid and other prochiral carboxylic acids under mild conditions. The catalytic hydrogenation of itaconic acid by I was examined under a variety of conditions, and the addition of triethylamine was found to effect high enantioselectivities (> 90% ee). 1H and 31P NMR examinations of reaction mixtures of I and itaconic acid under conditions similar to the hydrogenation suggested the formation of ruthenium species containing one binap chelate.

Asymmetric hydrogenation of prochiral alkenes catalysed by ruthenium complexes of (R)-(+)-2,2′-bis(diphenylphosphino)-1,1′-binaphthyl

Two chiral ruthenium(II) complexes containing (R)-(+)-2,2′-bis(diphenylphosphino)-1,1′-binaphthyl[(R)-BINAP] were found to be effective catalysts for the asymmetric hydrogenation of 2-acylaminoacrylic and 2-acylaminocinnamic acids under mild conditions, to afford N-acyl-(R)-α-amino acids with 49–95% optical purity. The differences between the asymmetric hydrogenations effected by RuII- and RhI-(R)-BINAP systems are discussed. Asymmetric hydrogenation of methylenesuccinic acid and its derivatives with Ru-(R)-BINAP is also described.