The osmium complex trans-[OsCl2(PPh3)2(en)] (2) was prepared by reaction of [OsCl2(PPh3)3] (1a) with ethylenediamine (en), whereas the diphosphine derivatives trans-[OsCl2(dppf)(NN)] (NN = en (3), bn (4; bn = 1,4-butanediamine)) and trans-[OsCl2(dpbp)(en)] (5) were obtained from 1a, dppf or dpbp, and the corresponding NN ligand in CH2Cl2 or toluene. An X-ray diffraction study has been provided for 3. The isolation of the chiral derivatives trans-[OsCl2(diphosphine)((R,R)-dpen)] (diphosphine = dppf (6), dpbp (7), (R,R)-skewphos (8)) was achieved by reacting 1a with the diphosphine and (R,R)-dpen in toluene. Treatment of the precursor [Os2Cl4(P(m-tolyl)3)5] (1b) with en afforded [OsCl2(P(m-tolyl)3)2(en)] (9), while reaction of 1b with dppb and N,N-dmen gave [OsCl2(dppb)(N,N-dmen)] (10). The chiral derivatives [OsCl2(diphosphine)(NN)] (11-21; diphosphine = (S)-MeObiphep, (R)-MeObiphep, (R)-xylMeObiphep, (R)-binap, (S)-xylbinap, (R)-xylbinap, (R,S)-Josiphos NN = en, (R,R)-dpen, (R)-daipen, (R,R)-dppn) were prepared from 1b and the corresponding diphosphine and NN ligands in toluene. The monohydride trans-[OsHCl(P(m-tolyl)3)2(en)] (22) was synthesized by reaction of 1b with H2 (1 atm) in the presence of NEt3, followed by addition of en in toluene. Similarly, trans-[OsHCl(dppf)(en)] (23) was synthesized from 1a, H2, and NEt3, followed by treatment with dppf and en. Complexes 2-5, 9, 10, 22, and 23 efficiently catalyzed the hydrogenation of acetophenone with H2 under low pressure (5 atm) at 60-70 °C in ethanol (1-2 mol % of NaOEt) with the ratio S/C = 5000-10000. The chiral derivatives 6-8 and 11-21 afforded the asymmetric hydrogenation of acetophenone with up to 90% ee by combining bulky xylyl-substituted MeObiphep or binap-type ligands with (R)-daipen or (R,R)-dpen ligands. Catalytic transfer hydrogenation of acetophenone was observed with 3, 6, and 7 (S/C = 2000) in 2-propanol and in the presence of NaOiPr (2 mol %) at 60-82 °C.

OsXCl(phosphine)2(diamine) and OsXCl(diphosphine)(diamine) (X = Cl, H) Complexes for Ketone Hydrogenation

Barbato, Cinzia;Baldino, Salvatore;Ballico, Maurizio;Figliolia, Rosario;Magnolia, Santo;Siega, Katia;Strazzolini, Paolo;Baratta, Walter
2018-01-01

Abstract

The osmium complex trans-[OsCl2(PPh3)2(en)] (2) was prepared by reaction of [OsCl2(PPh3)3] (1a) with ethylenediamine (en), whereas the diphosphine derivatives trans-[OsCl2(dppf)(NN)] (NN = en (3), bn (4; bn = 1,4-butanediamine)) and trans-[OsCl2(dpbp)(en)] (5) were obtained from 1a, dppf or dpbp, and the corresponding NN ligand in CH2Cl2 or toluene. An X-ray diffraction study has been provided for 3. The isolation of the chiral derivatives trans-[OsCl2(diphosphine)((R,R)-dpen)] (diphosphine = dppf (6), dpbp (7), (R,R)-skewphos (8)) was achieved by reacting 1a with the diphosphine and (R,R)-dpen in toluene. Treatment of the precursor [Os2Cl4(P(m-tolyl)3)5] (1b) with en afforded [OsCl2(P(m-tolyl)3)2(en)] (9), while reaction of 1b with dppb and N,N-dmen gave [OsCl2(dppb)(N,N-dmen)] (10). The chiral derivatives [OsCl2(diphosphine)(NN)] (11-21; diphosphine = (S)-MeObiphep, (R)-MeObiphep, (R)-xylMeObiphep, (R)-binap, (S)-xylbinap, (R)-xylbinap, (R,S)-Josiphos NN = en, (R,R)-dpen, (R)-daipen, (R,R)-dppn) were prepared from 1b and the corresponding diphosphine and NN ligands in toluene. The monohydride trans-[OsHCl(P(m-tolyl)3)2(en)] (22) was synthesized by reaction of 1b with H2 (1 atm) in the presence of NEt3, followed by addition of en in toluene. Similarly, trans-[OsHCl(dppf)(en)] (23) was synthesized from 1a, H2, and NEt3, followed by treatment with dppf and en. Complexes 2-5, 9, 10, 22, and 23 efficiently catalyzed the hydrogenation of acetophenone with H2 under low pressure (5 atm) at 60-70 °C in ethanol (1-2 mol % of NaOEt) with the ratio S/C = 5000-10000. The chiral derivatives 6-8 and 11-21 afforded the asymmetric hydrogenation of acetophenone with up to 90% ee by combining bulky xylyl-substituted MeObiphep or binap-type ligands with (R)-daipen or (R,R)-dpen ligands. Catalytic transfer hydrogenation of acetophenone was observed with 3, 6, and 7 (S/C = 2000) in 2-propanol and in the presence of NaOiPr (2 mol %) at 60-82 °C.
File in questo prodotto:
File Dimensione Formato  
barbato.organomet2018.pdf

non disponibili

Tipologia: Versione Editoriale (PDF)
Licenza: Non pubblico
Dimensione 805.75 kB
Formato Adobe PDF
805.75 kB Adobe PDF   Visualizza/Apri   Richiedi una copia

I documenti in IRIS sono protetti da copyright e tutti i diritti sono riservati, salvo diversa indicazione.

Utilizza questo identificativo per citare o creare un link a questo documento: https://hdl.handle.net/11390/1124095
Citazioni
  • ???jsp.display-item.citation.pmc??? ND
  • Scopus 10
  • ???jsp.display-item.citation.isi??? 8
social impact