Racemic (()-3,3¢-bis(diphenylphosphinyl)-1,1¢-dimethyl-2,2¢-biindole (1c) (N-Me-2-BINPO) and (()- 3,3¢-bis(diphenylphosphinyl)-1,1¢-bis(methoxymethyl)-2,2¢-biindole (1d) (N-MOM-2-BINPO) were synthesized in satisfactory yields following a three-step reaction sequence, starting from indole. Resolution of racemic 1c and 1d was achieved through fractional crystallization of their diastereomeric adducts with optically active dibenzoyl tartaric acids, followed by alkaline decomplexation of the diastereomerically pure salts. Their trichlorosilane reduction gave enantiopure phosphines (+)- and (-)-(1a) (N-Me-2-BINP) and (+)- and (-)-(1b) (N-MOM-2-BINP). The electrochemical oxidative potential of 1a and 1b was found to be 0.52 and 0.60 V, respectively. Both the enantiomers of (1a) were tested as ligands of Ru(II) in asymmetric hydrogenation reactions of R- and â-oxoesters. Reactions were found to be outstandingly fast and enantioselection quite good. Comparative kinetic experiments on the hydrogenation reaction of methyl acetoacetate carried out with 1a, 1c, BINAP, and other biheteroaromatic diphosphines as ligands of Ru(II) demonstrated that all the reactions follow a first-order kinetic. A linear relationship was found between the kinetic constant log and the electrochemical oxidative potential of the diphosphine ligand.

3,3'-Bis(Diphenylphosphino)-1,1'-Disubstituited-2,2'-Biindoles: Easily Accessible, Electron-Rich, Chiral Diphosphine Ligands for Homogeneous Enantioselective Hydrogenation of Oxoesters

Rizzo S;
2000

Abstract

Racemic (()-3,3¢-bis(diphenylphosphinyl)-1,1¢-dimethyl-2,2¢-biindole (1c) (N-Me-2-BINPO) and (()- 3,3¢-bis(diphenylphosphinyl)-1,1¢-bis(methoxymethyl)-2,2¢-biindole (1d) (N-MOM-2-BINPO) were synthesized in satisfactory yields following a three-step reaction sequence, starting from indole. Resolution of racemic 1c and 1d was achieved through fractional crystallization of their diastereomeric adducts with optically active dibenzoyl tartaric acids, followed by alkaline decomplexation of the diastereomerically pure salts. Their trichlorosilane reduction gave enantiopure phosphines (+)- and (-)-(1a) (N-Me-2-BINP) and (+)- and (-)-(1b) (N-MOM-2-BINP). The electrochemical oxidative potential of 1a and 1b was found to be 0.52 and 0.60 V, respectively. Both the enantiomers of (1a) were tested as ligands of Ru(II) in asymmetric hydrogenation reactions of R- and â-oxoesters. Reactions were found to be outstandingly fast and enantioselection quite good. Comparative kinetic experiments on the hydrogenation reaction of methyl acetoacetate carried out with 1a, 1c, BINAP, and other biheteroaromatic diphosphines as ligands of Ru(II) demonstrated that all the reactions follow a first-order kinetic. A linear relationship was found between the kinetic constant log and the electrochemical oxidative potential of the diphosphine ligand.
2000
Istituto di Scienze e Tecnologie Molecolari - ISTM - Sede Milano
Phosphines
Homogeneous Catalysis
Hydrogenation
File in questo prodotto:
File Dimensione Formato  
prod_257036-doc_112836.pdf

solo utenti autorizzati

Descrizione: 3,3¢-Bis(diphenylphosphino)-1,1¢-disubstituted-2,2¢-biindoles
Tipologia: Versione Editoriale (PDF)
Dimensione 101.51 kB
Formato Adobe PDF
101.51 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/20.500.14243/202925
Citazioni
  • ???jsp.display-item.citation.pmc??? ND
  • Scopus ND
  • ???jsp.display-item.citation.isi??? ND
social impact