Complejos quirales derivados de sales de lantánidos (III) como catalizadores enantioselectivos de la condensación nitroaldólica y análogas

  1. Tur Espinosa, Fernando
Supervised by:
  1. José Manuel Saá Rodríguez Director

Defence university: Universitat de les Illes Balears

Fecha de defensa: 05 May 2008

Committee:
  1. Carmen Nájera Domingo Chair
  2. Antonio Frontera Beccaria Secretary
  3. Lorenzo Di Bari Committee member
  4. Claudio Palomo Nicolau Committee member
  5. Juan Carlos Carretero Gonzálvez Committee member

Type: Thesis

Teseo: 275326 DIALNET

Abstract

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.