The reaction of r-nitro ketones to the corresponding a-hydroxy ketones under basic aqueous conditions, a novcl tr;tnsforniation. was studied. The investigation revealed that the reaction is only possible with I-nitro kctotics that are CH-acidic in the %'-position and readily deprotonated under the reaction conditions. The N O 2 OH exchange was established to proceed with retention of configuration at the stereogenic center, and I.iheling expcriments have shown that the O H 0-atom originates. to a great extent, from the solvent. In particular, the \tercochemical course of the reaction and the incorporation of external nucleophiles led us to propose a mc.ch;inism that involves neighboring-group participation. The product formation is explained by a double S,2 1-caction. which proceeds virr a Fmor.skii-like cyclopropanone intermediate.

A Novel NO 2 /OH Exchange in α-Nitro Ketones: A Mechanistic Investigation.--(YURDAKUL, A.; GURTNER, C.; JUNG, E.-S.; LORENZI-RIATSCH, A.; LINDEN, A.; GUGGISBERG, A.; BIENZ, S.; HESSE, M.; Helv.