Racemising 3-aryl-3-hydroxy-2-oxindoles in a Pickering emulsion under acid catalysis and its application to dynamic kinetic resolution

Abstract

3-Aryl-3-hydroxy-2-oxindoles were racemised under acid-catalysis in a water-in-oil Pickering emulsion comprising toluene and aqueous H₂SO₄. The developed biphasic methodology overcomes the decomposition issues often encountered during alcohol racemisation and affords high substrate recoveries. Successfully combining racemisation with enantioselective acylation led to the first dynamic kinetic resolution of an oxindole derivative.