Synthesis of 4-Hydroxyindolin-2-ones via Phosphoric Acid-Mediated Annulation of β-Nitrostyrenes with 1,3-Cyclohexanedione

Abstract

The efficient synthesis of 4-hydroxy-3-arylindolin-2-ones via phosphoric acid-mediated annulation of various βnitrostyrenes and 1,3-cyclohexanedione is described. This annulation reaction gives a practical method for affording a diverse set of oxindoles, having simple experimentation, readily available starting materials, and very good yields. Additionally, substituted 1,3cyclohexanediones under the same conditions afforded tetrahydrobenzofuran oxime compounds.