Ruthenium phosphine complexes have been widely examined in homogeneous hydrogenation (HY) and transfer hydrogenation reactions (TH), which are cost-effective and environmentally benign ways accepted in the industry for the reduction of carbonyl compounds. On account of the reversibility of the C-H bond activation, ruthenium catalysts have attracted a great deal of interest for a number of organic transformations, including borrowing hydrogen reactions. In this context, the design of efficient chelating and non-innocent ligands is crucial to achieve high activity and retard catalyst deactivation. Highly efficient Ru and Os catalysts for both TH and HY reactions were obtained by our group with ligands based on the 2-(aminomethyl)pyridine motif (A). More productive catalysts were subsequently developed by employment of pincer terdentate CNN ligands showing a metal-carbon σ-bond (B).1 These complexes allow fast reduction of ketones and aldehydes, including some biomass derivatives (5-HMF, ethyl levulinate), with H2, 2-propanol or ammonium formate at S/C up to 105. Employment of chiral catalysts in the ketone reduction afforded alcohols with up to 99% ee. The Ru and Os derivatives A and B can also catalyze the acceptorless DHY of alcohols to ketones and other transformations involving alcohol C-H activation, namely alcohol racemization, deuteration and ketone α-alkylation. Evidence has been provided that the catalytically active Ru hydride species are in rapid equilibrium with metal-amino alkoxides.

Highly Efficient Hydrogenation Ruthenium and Osmium Catalysts based on Ampy type Ligands

Maurizio Ballico
Primo
;
Rosario Figliolia
Secondo
;
Walter Baratta
Ultimo
2020-01-01

Abstract

Ruthenium phosphine complexes have been widely examined in homogeneous hydrogenation (HY) and transfer hydrogenation reactions (TH), which are cost-effective and environmentally benign ways accepted in the industry for the reduction of carbonyl compounds. On account of the reversibility of the C-H bond activation, ruthenium catalysts have attracted a great deal of interest for a number of organic transformations, including borrowing hydrogen reactions. In this context, the design of efficient chelating and non-innocent ligands is crucial to achieve high activity and retard catalyst deactivation. Highly efficient Ru and Os catalysts for both TH and HY reactions were obtained by our group with ligands based on the 2-(aminomethyl)pyridine motif (A). More productive catalysts were subsequently developed by employment of pincer terdentate CNN ligands showing a metal-carbon σ-bond (B).1 These complexes allow fast reduction of ketones and aldehydes, including some biomass derivatives (5-HMF, ethyl levulinate), with H2, 2-propanol or ammonium formate at S/C up to 105. Employment of chiral catalysts in the ketone reduction afforded alcohols with up to 99% ee. The Ru and Os derivatives A and B can also catalyze the acceptorless DHY of alcohols to ketones and other transformations involving alcohol C-H activation, namely alcohol racemization, deuteration and ketone α-alkylation. Evidence has been provided that the catalytically active Ru hydride species are in rapid equilibrium with metal-amino alkoxides.
File in questo prodotto:
File Dimensione Formato  
Baratta-abstract.pdf

accesso aperto

Descrizione: articolo principale
Tipologia: Abstract
Licenza: Creative commons
Dimensione 282.7 kB
Formato Adobe PDF
282.7 kB Adobe PDF Visualizza/Apri

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/11390/1200661
Citazioni
  • ???jsp.display-item.citation.pmc??? ND
  • Scopus ND
  • ???jsp.display-item.citation.isi??? ND
social impact