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

Abstract Using catalytic amounts of Ni complexes the tertiary α-hydroxyketones 1-benzoylcyclobutanol 1 and 1-benzoylcyclopentanol 3 undergo α-ketol rearrangement. The use of the chiral ligand 2,6-bis[(4 S )-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.