Asymmetric catalysis.: Part 137:: Nickel catalysed enantioselective α-ketol rearrangement of 1-benzoylcycloalkanols

Using catalytic amounts of Ni complexes the tertiary alpha -hydroxyketones 1-benzoylcyclobutanol 1 and 1-benzoylcyclopentanol 3 undergo alpha -ketol rearrangement. The use of the chiral ligand 2,6-bis[(4S)-isopropyl-2-oxazolin-2-yl]pyridine gave an enantiomeric excess of about 34% for both systems, forming (-)-2-hydroxy-2-phenylcyclopentanone 2 and (R)-(-)-2-hydroxy-2-phenylcyclohexanone 4. 1-Benzoylcyclohexanol 5 could not be catalytically rearranged to 6 under these conditions. (C) 2001 Elsevier Science Ltd. All rights reserved.