Enantiopure fluorous bis(oxazolines): synthesis and applications in catalytic asymmetric reactions.
Various enantiopure fluorous bis(oxazolines) with fluorine content between 52.7 and 58.7% have been synthesized by a simple reaction sequence that involved the introduction of two fluorinated ponytails by alkylation of the corresponding nonfluorous bis(oxazolines). These new ligands have been used in palladium-catalyzed alkylation of rac-(E)-1,3-diphenylpropenyl acetate with carbon nucleophiles and in copper-catalyzed oxidation of cycloalkenes; these ligands exhibited enantioselectivities up to 98 and 77%, respectively, quite close to the values obtained using the analogous nonfluorous bis(oxazolines). These ligands could be easily recovered by liquid-liquid extraction or solid-liquid separation and reused with the same enantioselectivities.
Bayardon
Jerome
J
Laboratoire de Synthèse Asymétrique, associé au CNRS, ESCPE Lyon, Université Claude Bernard Lyon 1, 43, boulevard du 11 novembre 1918, 69622 Villeurbanne Cedex, France.
Sinou
Denis
D