Ruthenium complexes, -1,1’-binaphthyl

Fig. 5.3. (a) View of (S)-BINAP-ruthenium complex showing the chiral environment, (b) Relationship of reactant to chiral environment showing preferred orientation. The binaphthyl rings are omitted for clarity. Adapted from J. 

The enantioselective oxidative coupling of 2-naphthol itself was achieved by the aerobic oxidative reaction catalyzed by the photoactivated chiral ruthenium(II)-salen complex 73. 2 it reported that the (/ ,/ )-chloronitrosyl(salen)ruthenium complex [(/ ,/ )-(NO)Ru(II)salen complex] effectively catalyzed the aerobic oxidation of racemic secondary alcohols in a kinetic resolution manner under visible-light irradiation. The reaction mechanism is not fully understood although the electron transfer process should be involved. The solution of 2-naphthol was stirred in air under irradiation by a halogen lamp at 25°C for 24 h to afford BINOL 66 as the sole product. The screening of various chiral diamines and binaphthyl chirality revealed that the binaphthyl unit influences the enantioselection in this coupling reaction. The combination of (/f,f )-cyclohexanediamine and the (R)-binaphthyl unit was found to construct the most matched hgand to obtain the optically active BINOL 66 in 65% ee. 

The moderate Lewis acidity of ruthenium complexes was used to promote catalytic Diels-Alder reaction of dienes and acrolein derivatives [21-23]. The enantioselective Diels-Alder reaction of methacrolein with dienes was catalyzed with cationic ruthenium complexes containing an arene or cyclo-pentadienyl (Cp) ligand and a chiral ligand such as phosphinooxazoline, pyridyl-oxazoline, monoxidized 2,2 -bis(diphenylphosphino)-1, T-binaphthyl (BINPO)or l,2-bis[bis(pentafluorophenyl)phosphanyloxy]-l,2-diphenylethane (BIPHOP-F). The reaction gave the cycloadduct in high yields with excellent... 

Ruthenium complexes of chiral phosphines notably BINAP, 2,2 -bis(diphenyl-phosphino)-l,l -binaphthyl are very useful for industrial hydrogenations and H-transfer hydrogenation of alkenes and ketones. This is due to high turnover numbers and enantiomeric excesses (ee) of the products. A specific example41 of an... 

Kawano, H., Ikariya, T., Ishii, Y., Saburi, M., Yoshikawa, S., Uchida, Y., Kumobayashi, H. Asymmetric hydrogenation of prochiral alkenes catalyzed by ruthenium complexes of (R)-(+)-2,2 -bis(diphenylphosphino)-1,1 -binaphthyl. J. Chem. Soc., Perkin Trans. 11989, 1571-1575. 

Rhodium and ruthenium complexes of 2,2 -bis(diphenylphosphino)-l,l -binaphthyl (BINAP) have frequently been used as catalysts for enantioselective hydrogenation of olefins and ketones." "" From consideration of the literature on this subject, it was proposed that the presence of a mono-oxidized BINAP in an organometallic catalyst could have interesting consequences." Accordingly, Rh(BINAP)(CO)Cl was prepared, and upon reaction with O2, (BINAP(0))Rh(CO)Cl was formed. These compounds were authenticated by X-ray crystallography, and IR and NMR spectroscopies. The kinetics of this reaction were monitored by solution (chloroform was the solvent) IR spectroscopy. In the absence of added CO, the oxygenated compound was formed in about 50% yield. BINAP(0)2 and CO2 are also produced. Plots of obs (from loss of reactant) versus [O2] at various temperatures yielded... 

Non-porphyrin ruthenium complexes such as [RuCl(DPPP)2] (DPPP = l,3-bis (diphenylphosphino)propane), [Ru(6,6-Cl2bpy)2(H20)2], binaphthyl-mthenium complex, and RUCI3 catalyze oxidations of alkenes with PhIO [45], t-BuOOH [46], PhI(OAc)2 [47], or H2O2 [48] to give the corresponding epoxides in moderate yields. 

The newly developed ruthenium catalyst 184, having 2,2-bis(diphenyl-phosphanyl)-l, 1-binaphthyl (BINAP) and 2-picolylamine as ligands, effects asymmetric reduction of/-butyl (2-thienyl) ketone under mild conditions with very high enantioselectivity <2005JA8288>. The (6 )-enantiomer of the complex leads to the (/ )-alcohol with 98% ee (Equation 84). 

Various oxidations with [bis(acyloxy)iodo]arenes are also effectively catalyzed by transition metal salts and complexes [726]. (Diacetoxyiodo)benzene is occasionally used instead of iodosylbenzene as the terminal oxidant in biomimetic oxygenations catalyzed by metalloporphyrins and other transition metal complexes [727-729]. Primary and secondary alcohols can be selectively oxidized to the corresponding carbonyl compounds by PhI(OAc)2 in the presence of transition metal catalysts, such as RuCls [730-732], Ru(Pybox)(Pydic) complex [733], polymer-micelle incarcerated ruthenium catalysts [734], chiral-Mn(salen)-complexes [735,736], Mn(TPP)CN/Im catalytic system [737] and (salen)Cr(III) complexes [738]. The epox-idation of alkenes, such as stilbenes, indene and 1-methylcyclohexene, using (diacetoxyiodo)benzene in the presence of chiral binaphthyl ruthenium(III) catalysts (5 mol%) has also been reported however, the enantioselectivity of this reaction was low (4% ee) [739]. 

Ohta T, Takaya H, Noyori R. Bis(diarylphosphino)-l,l binaphthyl (BINAP)-ruthenium(II) dicarboxylate complexes new, highly efficient catalysts for asymmetric hydrogenations. Inorg. Chem. 1988 27(3) 566-569. 

Mashima K, Nakamura T, Matsuo Y, Tani K. Convenient synthesis of anionic dinuclear ruthenium(ll) complexes [NR2H2] [ RuCl(diphosphine) 2(p.-Cl)3] [diphosphine = 2,2 -bis(diphenylphosphino)-l,l -binaphthyl, 2,2 -bis(di (p-tolyl)phosphino)-l,l -binaphthyl, and l,2-bis(diphenyl-phosphino)benzene] crystal structure of [NEt2H2][ RuCl... 

Derivates of the chiral complex, bis(carboxylato) (R)-2,2 -bis(diphenyl-phosphino-l,r-binaphthyl ruthenium(II), [Ru(BINAP)(02CR)2], (1),... 

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