Zanetti, Nadia C. Spindler, Felix Spencer, John Togni, Antonio Rihs, Grety Synthesis, Characterization, and Application in Asymmetric Hydrogenation Reactions of Chiral Ruthenium(II) Diphosphine Complexes Four new complexes of the type [Ru(CF<sub>3</sub>CO<sub>2</sub>)<sub>2</sub>(X)<sub>2</sub>(PP)] <b>7</b> (X = methanol or ethanol, PP = chiral diphosphine) have been synthesized from the reaction of PP with [Ru<sub>2</sub>(CF<sub>3</sub>CO<sub>2</sub>)<sub>4</sub>(H<sub>2</sub>O)(COD)<sub>2</sub>] and characterized by both NMR spectroscopy and single-crystal X-ray diffraction studies. A common feature of these complexes is a pseudooctahedral geometry for ruthenium, an unusual monodentate ligation mode for the mutually <i>trans</i> trifluoroacetate groups, along with two solvent molecules coordinated in mutual <i>cis</i> positions (MeOH for <b>7a</b> and <b>7b</b>, EtOH for <b>7c</b>). <b>7a</b> (PP = (2<i>S,</i>4<i>S</i>)-BDPP) belongs to the orthorhombic <i>P</i>2<sub>1</sub>2<sub>1</sub>2<sub>1</sub> space group, <i>Z</i> = 4, <i>a</i> = 9.896(1) Å, <i>b</i> = 19.099(3) Å, and <i>c</i> = 19.689(2) Å. <b>7b</b> (PP = (4<i>S,</i>5<i>S</i>)-DIOP) also crystallizes in the orthorhombic <i>P</i>2<sub>1</sub>2<sub>1</sub>2<sub>1</sub> space group, <i>Z</i> = 4, <i>a</i> = 12.679(1) Å, <i>b</i> = 16.744(2) Å, and <i>c</i> = 18.944(2) Å. <b>7c</b> (PP = (<i>R</i>)-1-[(<i>S)</i>-2-(diphenylphosphino)ferrocenyl]ethyldicyclohexylphosphine, abbreviated as PPFCy<sub>2</sub>) belongs to the monoclinic <i>P</i>2<sub>1</sub> space group, <i>Z</i> = 4, <i>a</i> = 18.153(2) Å, <i>b</i> = 12.364(2) Å, <i>c</i> = 20.431(1) Å, and β = 97.40(1)°. The air-stable [RuCl(<i>p</i>-cymene)(PP)]PF<sub>6</sub> <b>9</b> were synthesized from the reaction of PP with [RuCl<sub>2</sub>(<i>p-</i>cymene)]<sub>2</sub> in a refluxing CH<sub>2</sub>Cl<sub>2</sub>/EtOH mixture, followed by metathesis with KPF<sub>6</sub> in MeOH, in 72−89% yields (PP = <i>(S)-(R)</i> or (<i>R)-(S</i>)-2-(diphenylphosphino or arsino)ferrocenyl]ethylbisphosphine derivative). <b>9a</b> (PP = (<i>S</i>)-(<i>R</i>)-PPFCy<sub>2</sub> crystallizes in the monoclinic space group <i>P</i>2<sub>1</sub>, <i>Z</i> = 2, <i>a</i> = 11.965(2) Å, <i>b</i> = 14.852(3) Å, <i>c</i> = 13.999(2) Å, and β = 111.50(2)°. Complexes <b>7</b> were probed for their catalytic behavior in the hydrogenation of methyl acetamidocinnamate <b>10</b>, acetamidocinnamic acid <b>11</b>, and dimethyl itaconate <b>12</b>. Using a typical substrate to catalyst ratio of 50−100:1 and p(H<sub>2</sub>) = 50 bar, modest enantiomeric excesses (ee) of up to 75% were achieved. The highest ee's were attained in CH<sub>2</sub>Cl<sub>2</sub> or a 5:4 THF/CH<sub>2</sub>Cl<sub>2</sub> mixture, whereas higher activities were observed when methanol was employed as solvent. The addition of NEt<sub>3</sub> had a beneficial effect on the ee of the reactions involving <b>11</b>, whereas with <b>10</b> a detrimental effect was observed. The reactions involving <b>12 </b>gave poor enantioselectivity. cis positions;CF 3 CO 2;enantiomeric excesses;THF;space group P 2 1;monodentate ligation mode;BDPP;NEt 3;Ru 2;DIOP;P 2 1 2 1 2 1 space group;acetamidocinnamic acid 11;PPFCy 2;7 b;7 c;KPF 6;50 bar;Å.;trans trifluoroacetate groups;CH 2 Cl 2;catalyst ratio;RuCl 2;Asymmetric Hydrogenation Reactions;P 2 1 space group;methyl acetamidocinnamate 10;dimethyl itaconate 12;pseudooctahedral geometry;NMR spectroscopy;chiral diphosphine 1996-01-23
    https://acs.figshare.com/articles/journal_contribution/Synthesis_Characterization_and_Application_in_Asymmetric_Hydrogenation_Reactions_of_Chiral_Ruthenium_II_Diphosphine_Complexes/3776382
10.1021/om9506781.s002