A series of chiral di-, tri- and tetra amine ligands were synthesised from enantiomerically pure 1,2-cyclohexanediamine and 1,2-diphenylethanediamine and, in combination with Ru(II) or Fe(II), employed as asymmetric catalysts in the epoxidation of aromatic alkenes, hydrosilylation of acetophenone, nitro-aldol reaction and asymmetric transfer hydrogenation (ATH) of different ketones. A novel class of tridentate ruthenium catalysts of general structure 239 below were developed. Specifically, a novel class of tridentate ligand was synthesised and a derivative of (R,R)-N-tosyl-1,2-diphenyl-1,2-ethylenediamine ((R,R)-TsDPEN) and was found to provide the best activity and selectivity in reduction reactions with Ru3(CO)12. Reaction conditions were optimised using 239 for the ruthenium-catalysed ATH of a number of ketones. In particular, it was found that the presence of meta-methoxy substituent on the aromatic ring of the substrate yields optimal results under the ATH conditions employed for 48 h (98% conv., 94% ee). Also, aryl ketones substituted at the ortho position were reduced in almost quantitative yield, with enantiomeric excesses greater than 90% in some cases.
| Identifer | oai:union.ndltd.org:bl.uk/oai:ethos.bl.uk:582256 |
| Date | January 2012 |
| Creators | Darwish, Moftah |
| Publisher | University of Warwick |
| Source Sets | Ethos UK |
| Detected Language | English |
| Type | Electronic Thesis or Dissertation |
| Source | http://wrap.warwick.ac.uk/56286/ |
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