Complejos quirales derivados de sales de lantánidos (III) como catalizadores enantioselectivos de la condensación nitroaldólica y análogas
- Tur Espinosa, Fernando
- José Manuel Saá Rodríguez Doktorvater/Doktormutter
Universität der Verteidigung: Universitat de les Illes Balears
Fecha de defensa: 05 von Mai von 2008
- Carmen Nájera Domingo Präsident/in
- Antonio Frontera Beccaria Sekretär/in
- Lorenzo Di Bari Vocal
- Claudio Palomo Nicolau Vocal
- Juan Carlos Carretero Gonzálvez Vocal
Art: Dissertation
Zusammenfassung
We have synthesized BINOL (2,2'-dihydroxy-1,1'-binaphtalene) derivatives having dialkylaminomethyl groups at C-3 and C-3' generically named binaphtolamines. We assessed the ability of these ligands to coordinate lanthanide (III) salts. We found that the combination of 3,3'-bis[(diethylamino)methyl]-2,2'-dihydroxy-1,1'-binaphtalene (BINOLAM) with lanthanide (III) triflates led to the formation of chiral complexes characterized by having 3:1 stoichiometry, D3 symmetry and predetermined chirality on the lanthanide center. They are shelf stable species i.e., storable for months without any special precautions. They possess an arrayed network of Lewis acid-Bronsted acid-base Bronsted centres (LABABB) which is relevant to explain its catalytic activity. In solution, these species are kinetically labile and are stable in most anhydrous organic solvents. We have studied the ability of these complexes to work as enantioselective catalysts in the direct nitroaldol (Henry) reaction of aldehydes and α-trifluoromethyl ketones with nitromethane thereby giving rise to the corresponding β-nitroaldols and α-trifluoromethyl tertiary nitroaldols with moderate to high chemical yields and enantioselectivity.