1-Phenylisatin-Mediated Redox-Neutral Ketone to Carboxylic Acid Conversion.

Herein, a general and efficient ketone to carboxylic acid conversion method mediated by isatin was developed under redox-neutral conditions. Unlike the traditional oxidative ketone to carboxylic acid conversion methodologies that are not compatible with oxidation-sensitive functional groups, this method is mild and tolerates a wide range of sensitive functional groups, which is a good complement to the existing ketone to carboxylic acid conversion methodologies. In addition, in the presence of cyclic ketones, including steroids, the 2-oxindole moiety could be incorporated into the product in a ring opening fashion, which would provide a general platform for the synthesis of a variety of 2-oxindole-containing biorelevant molecules. In addition, the control experiment reveals that this reaction proceeds through a σ-π cross-metathesis pathway that accounts for this oxidant-free ketone to carboxylic acid conversion.