Over the last fifty years, the evolution of organic synthesis has reached a high level of sophistication, allowing for the obtention of highly complex molecules through protocols that provide specific chemo-, regio- and stereoselectivity. Furthermore, in order to be competitive and meet the economic and environmental demands, high atom efficiency and a decrease of waste generated are essential, especially in accordance to the principles of green chemistry. The development of synthetic protocols that can account for these requirements can only be accomplished in many cases using catalysis.
Palladium catalysts are a versatile and very efficient instrument in synthetic chemistry. Although phosphines have played a major role in palladium catalysed coupling reactions, more recently, the use of the relatively new N-heterocyclic carbene ligands, has led to significant improvements in activity, easier handling and better control of metal to ligand stoichiometry.
Chapter 1 Past and present of cross-coupling reactions, with particular emphasis on palladium catalysed couplings. Relevant ligands used including phosphines and N-heterocyclic carbenes (NHC), are explored. The importance of emerging environmental friendly processes and their impact on modern chemistry.
Chapter 2 provides a background on the telomerisation reaction, followed by an account of our investigation of the family of (NHC)PdCl2(TEA) (TEA = trimethylamine)catalysts.1 The reaction was examined by experimental means comparing the use of different telomers and taxogens.
Chapter 3 accounts for the metal catalysed synthesis of conjugated polymers. Background on the interest of water soluble conjugated polymers and methodologies.
Chapter 4 explores the application of NHC-Pd(II) complexes in the asymmetric aldol condensation reaction. An outline of the available organometallic catalysts and the use of chiral and non-chiral ligands is given. Complexes of type [(NHC)PdCl2(OAc)][TBA] have been tested in the condensation of isocyanoacetates with both aldehydes to yield oxazolines and imines to obtain imidazolines.
Chapter 5 future directions
