Resumen de Ligand design for palladium and iridium selective catalysts
This doctoral thesis focuses on the synthesis of new ligands and their application in two types of catalytic process: a) palladium catalysed carbonylation reactions and b) asymmetric reactions (hydrogenation of challenge substrates and C-C bond formation). In the first part of the thesis, the synthesis of a family of new diphosphine ligands and their application in Pd-catalysed carbonylation processes is described. These ligands were first used in the Pd-catalysed methoxycarbonylation of ethane, achieving high activity and selectivity. A mechanistic study on these catalytic systems revealed the resting state of this process. The new ligands were also applied in the aminocarbonylation and double-carbonylation of aryl iodides, achieving high level of chemoselectivity in each case. NMR studies on these systems led to the discovery and development of the first phosphine-free Pd-catalysed double-carbonylation of aryl iodides where the base used in the process revealed to also play a key role as ligand and nucleophile. The second part of this thesis describes the synthesis of new phosphino-imidazoline ligands and their application in the Ir-catalysed asymmetric hydrogenation of unfunctionalised olefines and imines achieving moderate enantioselectivities. These ligands were also applied in the Pd-catalysed allylic substitution reactions, achieving excellent enantioselectivities for a wide range of substrates and nucleophiles. An efficient recovery of the catalytic system was carried out by anchoring a phosphino-imidazoline ligand onto a polymer support or using ionic liquids as reaction medium.
