New axially dissymmetric ligand recoverable with fluorous solvent

Axially dissymmetric ligands with perfluoroalkyl groups, (Ra)-2,2'-bis[(R)-1-hydroxy-1H-perfluorooctyl]biphenyl [(Ra)-(R)(2)-1c] and its enantiomer, have been synthesized successfully by the coupling reaction of the corresponding aryl bromide using Ni(COD)(2). These ligands showed much higher asymmetric induction in the reaction of various aldehydes with diethylzinc than the trifluoromethyl (1a) or pentafluoroethyl (1b) analogues. Furthermore, 1c was recovered quantitatively by extraction with a fluorous solvent from the reaction mixture due to its high fluorine content. The recovered ligand 1c was pure enough to be reused without purification. The efficiency of 1c as the chiral ligand was not decreased at all even after seven times recycling (c) 2005 Elsevier Ltd. All rights reserved.