posted on 2013-12-06, 15:27authored byLouise M. Newman
This thesis describes the synthesis of novel ligands that include enantiomerically
pure acetal and oxazoline moieties. These ligands are utilised in a number of metalmediated
asymmetric syntheses.
All asymmetric acetals and pyridine based acetals are synthesised in good yield in a
single step from their corresponding enantiomerically pure diols. C2 symmetric
bisacetals are investigated as ligands in the organolithium and Grignard additions to
benzaldehyde with promising results. C2 symmetric bisacetals and pyridine based
acetals are tested for their ability to induce asymmetry in copper(l) catalysed
cyclopropanation of styrene using ethyl diazoacetate and the lanthanide(lII)
catalysed Diels-Alder cycloaddition involving Danishefsky's diene with little success.
Enantiomerically pure phosphinooxazoline ligands are available in good yield in two
steps from their corresponding enantiomerically pure aminoalcohols.
Enantiomerically pure acetal substituted pyridines and phosphinooxazoline ligands
are considered in the rhodium (I) catalysed hydrosilylation of ketones. Reaction
conditions for the more successful phosphinooxazoline ligands are optimised. Using
these ligands a range of enantiomerically enriched alcohols is presented in good
yield and enantiomeric excess. Novel phosphinooxazoline ligands are applied to the palladium(O) catalysed
allylic substitution reaction with excellent enantioselectivities of the substitution
product.