Supramolecular Catalytic Systems: Synthesis, Characterization and Application in Catalysis

Identifier:  TDX:3803

Handle: https://hdl.handle.net/20.500.11797/TDX3803

Authors:  Iniesta Beteta, Ester

Abstract:
This doctoral thesis encompasses the design and development of supramolecular catalysts derived from transition metal complexes and their application as catalysts in transformations of interest. The first part of the thesis focusses on the development of supramolecularly regulated copper(I) catalysts for the insertion of metal carbenes into O–H bonds leading to synthetically useful α-alkyl/aryl-α-alkoxy/aryloxy derivatives. The design, preparation, characterization and application of supramolecularly regulated copper(I) catalysts derived from bisoxazoline ligands is described. Our studies demonstrate that the catalytic performance of these systems can be modulated by the use of an external molecule (i.e. the regulation agent), which interacts with the polyethyleneoxy chain on the ligand (i.e. the regulation site) via supramolecular ion-dipole interactions. This approach has been applied to an array of structurally diverse alcohols (cycloalkyl, alkyl and aryl derivatives). Moreover, this methodology has been used to synthesize advanced synthetic intermediates of biologically relevant compounds. The second part of this thesis focusses on the use of halogen bonding interactions to construct the skeleton of metal complexes. The synthesis of new supramolecular platinum(II) and palladium(II) complexes by assembling two building blocks that incorporate phosphines as ligating groups, as well as complementary binding motifs for the assembly through halogen bonding, are reported. A set of structurally diverse platinum(II) and palladium(II) complexes derived from (halogen-bonded) diphosphines have been characterized in solution and in the solid state. A broad study of the reaction intermediates that led to the platinum(II) complexes has been performed. A tentative mechanistic rationalization for the formation of the platinum(II) complexes is proposed. The complex XBPhos-Pt has proved to be unreactive as a catalyst in cyclizations of enynes and in the hydrophenylation of ethylene. Strategies towards the activation of XBPhos-Pt and analogues for new chemical transformations are presented.