Asymmetric alpha-oxyacylation of cyclic ketones

Reaction of cyclic ketones with chiral N-alkyl-O-acyl hydroxylamines leads to the corresponding alpha-oxyacylated carbonyl compound in up to 89% ee. The levels of asymmetric induction were influenced by solvent polarity, acid strength and, to a lesser extent, temperature. Increasing the steric bulk around the nitrogen atom of the hydroxylamine reagent led to increased levels of asymmetric induction, which was also found to be detrimental to the yield observed for the transformation. Examination of N- and Osubstituents along with substrates revealed the scope and limitations of the procedure.