A new catalytic system for the asymmetric Baeyer–Villiger oxidation of monosubstituted prochiral cyclobutanones to γ-butyrolactones with high yields (40–99%) and enantioselectivities (45–87%) is described. Aluminium complexes with biaryl ligands and ionic liquids are presented. The incorporation of an ionic liquid in the complex structure was confirmed by the observed four-coordinate nature of the aluminium.
Key words
ionic liquids - lactones - biaryl ligands - aluminium complexes - asymmetric catalysis