Synthesis of 4‑Hydroxyindolin-2-ones\nvia Phosphoric\nAcid-Mediated Annulation of β‑Nitrostyrenes with 1,3-Cyclohexanedione

The efficient synthesis of 4-hydroxy-3-arylindolin-2-ones\nvia phosphoric\nacid-mediated annulation of various β-nitrostyrenes and 1,3-cyclohexanedione\nis described. This annulation reaction gives a practical method for\naffording a diverse set of oxindoles, having simple experimentation,\n readily available starting materials, and very good yields. Additionally,\nsubstituted 1,3-cyclohexanediones under the same conditions afforded\ntetrahydrobenzofuran oxime compounds.