Issue 4, 2008

BINAP-Ru and -Rhcatalysts covalently immobilised on silica and their repeated application in asymmetric hydrogenation

Abstract

We present the facile immobilisation of a chiral diphosphine ligand, BINAP, on a silica (high pore volume, low surface area). The protected ligand has been immobilised as a phosphine oxide and deprotected on the surface to prevent side reactions of unprotected phosphines with surface silanol groups. The resulting diphosphine ligand on silica was converted to both rhodium and ruthenium complexes. The novel materials were characterised using solid-state IR-DRIFT and 29Si and 31P CP-MAS NMR techniques as well as elemental content measurements. Ruthenium and rhodium catalysed asymmetric hydrogenation of various enamides, β-keto-esters and aromatic ketones is presented using immobilised BINAP ligands. The repeated use of the immobilised catalyst in five recycles demonstrates ‘homogeneous’ catalysis with ‘heterogeneous’ catalysts, thus reducing solvent waste, and loss of precious metal and or ligand.

Graphical abstract: BINAP-Ru and -Rh catalysts covalently immobilised on silica and their repeated application in asymmetric hydrogenation

Article information

Article type
Paper
Submitted
14 Sep 2007
Accepted
01 Feb 2008
First published
12 Mar 2008

Green Chem., 2008,10, 424-432

BINAP-Ru and -Rh catalysts covalently immobilised on silica and their repeated application in asymmetric hydrogenation

A. R. McDonald, C. Müller, D. Vogt, G. P.M. van Klink and G. van Koten, Green Chem., 2008, 10, 424 DOI: 10.1039/B714189K

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