A Novel NO2/OH Exchange in α-Nitro Ketones: A Mechanistic Investigation

Article abstract of DOI:10.1002/hlca.19980810547

The reaction of α-nitro ketones to the corresponding α-hydroxy ketones under basic aqueous conditions, a novel transformation, was studied. The investigation revealed that the reaction is only possible with α-nitro ketones that are CH-acidic in the α′-position and readily deprotonated under the reaction conditions. The NO₂/OH exchange was established to proceed with retention of configuration at the stereogenic center, and labeling experiments have shown that the OH O-atom originates, to a great extent, from the solvent. In particular, the stereochemical course of the reaction and the incorporation of external nucleophiles led us to propose a mechanism that involves neighboring-group participation. The product formation is explained by a double S_N2 reaction, which proceeds via a favorsii-like cyclopropanone intermediate.